Showing papers in "Journal of Prosthetic Dentistry in 2003"

Clinical complications with implants and implant prostheses.

Abstract: The purpose of this article is to identify the types of complications that have been reported in conjunction with endosseous root form implants and associated implant prostheses. A Medline and an extensive hand search were performed on English-language publications beginning in 1981. The searches focused on publications that contained clinical data regarding success/failure/complications. The complications were divided into the following 6 categories: surgical, implant loss, bone loss, peri-implant soft tissue, mechanical, and esthetic/phonetic. The raw data were combined from multiple studies and means calculated to identify trends noted in the incidences of complications. The most common implant complications (those with a greater than a 15% incidence) were loosening of the overdenture retentive mechanism (33%), implant loss in irradiated maxillae (25%), hemorrhage-related complications (24%), resin veneer fracture with fixed partial dentures (22%), implant loss with maxillary overdentures (21%), overdentures needing to be relined (19%), implant loss in type IV bone (16%), and overdenture clip/attachment fracture (16%). It was not possible to calculate an overall complications incidence for implant prostheses because there were not multiple clinical studies that simultaneously evaluated all or most of the categories of complications. Although the implant data had to be obtained from different studies, they do indicate a trend toward a greater incidence of complications with implant prostheses than single crowns, fixed partial dentures, all-ceramic crowns, resin-bonded prostheses, and posts and cores.

Resin-ceramic bonding: a review of the literature.

Abstract: Current ceramic materials offer preferred optical properties for highly esthetic restorations. The inherent brittleness of some ceramic materials, specific treatment modalities, and certain clinical situations require resin bonding of the completed ceramic restoration to the supporting tooth structures for long-term clinical success. This article presents a literature review on the resin bond to dental ceramics. A PubMed database search was conducted for in vitro studies pertaining to the resin bond to ceramic materials. The search was limited to peer-reviewed articles published in English between 1966 and 2001. Although the resin bond to silica-based ceramics is well researched and documented, few in vitro studies on the resin bond to high-strength ceramic materials were identified. Available data suggest that resin bonding to these materials is less predictable and requires substantially different bonding methods than to silica-based ceramics. Further in vitro studies, as well as controlled clinical trials, are needed.

Clinical complications in fixed prosthodontics

Abstract: The purpose of this article is to identify the incidence of complications and the most common complications associated with single crowns, fixed partial dentures, all-ceramic crowns, resin-bonded prostheses, and posts and cores. A Medline and an extensive hand search were performed on English-language publications covering the last 50 years. The searches focused on publications that contained clinical data regarding success/failure/complications. Within each type of prosthesis, raw data were combined from multiple studies and mean values calculated to determine what trends were noted in the studies. The lowest incidence of clinical complications was associated with all-ceramic crowns (8%). Posts and cores (10%) and conventional single crowns (11%) had comparable clinical complications incidences. Resin-bonded prostheses (26%) and conventional fixed partial dentures (27%) were found to have comparable clinical complications incidences. The 3 most common complications encountered with all-ceramic crowns were crown fracture (7%), loss of retention (2%), and need for endodontic treatment (1%). The 3 most common complications associated with posts and cores were post loosening (5%), root fracture (3%), and caries (2%). With single crowns, the 3 most common complications were need for endodontic treatment (3%), porcelain veneer fracture (3%), and loss of retention (2%). When fixed partial denture studies were reviewed, the 3 most commonly reported complications were caries (18% of abutments), need for endodontic treatment (11% of abutments), and loss of retention (7% of prostheses). The 3 most common complications associated with resin-bonded prostheses were prosthesis debonding (21%), tooth discoloration (18%), and caries (7%). (J Prosthet Dent 2003;90:31-41.) A complication has been defined 1 as “a secondary disease or condition developing in the course of a primary disease or condition.” Although complications may be an indication that clinical failure has occurred, this is not typically the case. It is also possible that complications may reflect substandard care. But once again, this is usually not true. Most of the time, complications are conditions that occur during or after appropriately performed fixed prosthodontic treatment procedures. Knowledge regarding the clinical complications that can occur in fixed prosthodontics enhances the clinician’s ability to complete a thorough diagnosis, develop the most appropriate treatment plan, communicate realistic expectations to patients, and plan the time intervalsneededforpost-treatmentcare.Althoughaplethora of articles present clinical complications data, none provide a comprehensive comparison of the complications associated with the most commonly used restorations/

Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.

Abstract: Statement of problem The ceramic composition and microstructure surface of all-ceramic restorations are important components of an effective bonding substrate. Both hydrofluoric acid etching and airborne aluminum oxide particle abrasion produce irregular surfaces necessary for micromechanical bonding. Although surface treatments of feldspathic and leucite porcelains have been studied previously, the high alumina-containing and lithium disilicate ceramics have not been fully investigated. Purpose The purpose of this study was to assess the surface topography of 6 different ceramics after treatment with either hydrofluoric acid etching or airborne aluminum oxide particle abrasion. Material and methods Five copings each of IPS Empress, IPS Empress 2 (0.8 mm thick), Cergogold (0.7 mm thick), In-Ceram Alumina, In-Ceram Zirconia, and Procera (0.8 mm thick) were fabricated following the manufacturer's instructions. Each coping was longitudinally sectioned into 4 equal parts by a diamond disk. The resulting sections were then randomly divided into 3 groups depending on subsequent surface treatments: Group 1, specimens without additional surface treatments, as received from the laboratory (control); Group 2, specimens treated by use of airborne particle abrasion with 50-μm aluminum oxide; and Group 3, specimens treated with 10% hydrofluoric acid etching (20 seconds for IPS Empress 2; 60 seconds for IPS Empress and Cergogold; and 2 minutes for In-Ceram Alumina, In-Ceram Zirconia, and Procera). Results Airborne particle abrasion changed the morphologic surface of IPS Empress, IPS Empress 2, and Cergogold ceramics. The surface topography of these ceramics exhibited shallow irregularities not evident in the control group. For Procera, the 50-μm aluminum oxide airborne particle abrasion produced a flattened surface. Airborne particle abrasion of In-Ceram Alumina and In-Ceram Zirconia did not change the morphologic characteristics and the same shallows pits found in the control group remained. For IPS Empress 2, 10% hydrofluoric acid etching produced elongated crystals scattered with shallow irregularities. For IPS Empress and Cergogold, the morphologic characteristic was honeycomb-like on the ceramic surface. The surface treatment of In-Ceram Alumina, In-Ceram Zirconia, and Procera did not change their superficial structure. Conclusion Hydrofluoric acid etching and airborne particle abrasion with 50-μm aluminum oxide increased the irregularities on the surface of IPS Empress, IPS Empress 2, and Cergogold ceramics. Similar treatment of In-Ceram Alumina, In-Ceram Zirconia, and Procera did not change their morphologic microstructure.

Fracture resistance of endodontically treated teeth restored with composite posts.

Abstract: Statement of Problem. The most recent application of fiber-reinforced composites involves their use as post and core systems to restore endodontically treated teeth. Even though this last application has been advertised and used clinically by many dentists, there is very little information regarding the physical properties of these post systems. Purpose. The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth. Material and Methods. Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel (ParaPost) control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called "narrow" and "flared" canals. For the narrow canal group, post spaces were prepared with the corresponding reamer to restore the teeth with FibreKor, Luscent anchors, and Ribbond posts of 1.5 mm, 1.6 mm, and 2.0 mm in diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same posts but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Prefabricated posts (FibreKor and Luscent anchors) for narrow and flared canals were cemented with an autopolymerized resin cement and a flowable composite, respectively, whereas customized Ribbond posts were luted with a light-polymerized flowable composite for both canal types. An additional set of 20 Ribbond posts with coronal portions of variable size and shape referred to as "Ribbond nonstandardized" were also prepared and evaluated. Specimens were loaded to failure (kg) with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. Data were analyzed with analysis of variance and Student t tests ( P Results. Statistical analysis revealed no significant difference between flared and narrow canals in mean load to failure between the post systems except for the Ribbond posts ( P P Conclusion. Results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite posts studied. However, the mode of failure or deflection of the fiber-reinforced composite posts is protective to the remaining tooth structure. (J Prosthet Dent 2003;89:360-7.)

A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics.

Abstract: One goal of the American Academy of Fixed Prosthodontics is regularly to publish comprehensive literature reviews on selected topics germane to the discipline of fixed prosthodontics. The following report is the result of this goal and focuses on provisional fixed prosthodontic treatment. Major subtopics include materials science and clinical considerations involving natural teeth and dental implants. The interrelationship between provisional and definitive fixed prosthodontic treatment is multifaceted and significant. Provisional therapy involves numerous materials and techniques that require special knowledge and technical experience. In this analysis, technical, clinical, and investigational articles are detailed and presented as a comprehensive literature review to provide contemporary guidelines. Referenced publications were found by conducting a Medline search and were limited to peer-reviewed, English-language articles published from 1970 to the present. Materials used with provisional treatment are discussed in terms of clinical selection and the influence of their physical properties on treatment outcome. Specific product names and manufacturers are included in this report only when they are cited in the original referenced publications.

Mechanical and physical properties of contemporary dental luting agents

Abstract: Statement of problem. New luting agents, particularly with adhesive capability, are being introduced in an attempt to improve clinical success. Independent studies of basic comparative data are necessary to characterize these materials in relation to mechanical and physical properties. Purpose. The purpose of this study was to compare the flexural strength, modulus of elasticity, and radiopacity and pH of representatives of 5 types (categories) of luting agents. Material and methods. The luting agents included a zinc phosphate, a conventional and a resin-modified glass ionomer, 2 dual-polymerizing resins ("photopolymerized" after mixing and "unphotopolymerized" conditions), and an auto-polymerizing resin. The specimens were prepared and the testing was conducted by 1 person to maximize standardization. Flexural strength (MPa) and modulus of elasticity (GPa) were determined on bar-shaped specimens (2 × 2 × 20 mm) at 24 hours and 3 months (n = 8). Radiopacity (mm Al) was measured by exposing 1 mm thick specimens along with an aluminum step wedge (n = 4). pH was measured using a pH electrode immediately after mixing; at 1, 5, 15, 30 minutes; and at 1, 2, 4, 6, and 24 hours (n = 4). The data were subjected to statistical analyses with analysis of variance and Duncan's multiple range test ( P Results. The resin luting agents (64 to 97 MPa) showed higher flexural strength than all other materials tested (7 to 27 MPa), with the "photopolymerized" (83 to 97 MPa) conditions higher than "unphotopolymerized" (64 to 81 MPa) ( P P P P P Conclusion. Within the limitations of this study the data showed a wide variation of material properties. The dual-polymerization resin luting agents tested showed the best combination of mechanical and physical properties combined with the highest setting pH. Photopolymerization of these resin-based materials was necessary to maximize strength and rigidity. (J Prosthet Dent 2003;89:127-34.)

Factors determining post selection: a literature review

Abstract: Most endodontically treated teeth require a post-and-core build-up for restoring the teeth to optimum health and function. Selection of an appropriate post-and-core system from the wide variety of those available may be a clinical dilemma. Therefore, the purpose of this article is to review the literature to identify the various factors that influence the selection of the post-and-core assembly. English-language peer-reviewed articles between 1961 and 2002 were identified using MEDLINE, as well as a hand search. The following key words were used: post, design, retention, fracture resistance, survivability, and esthetics. Selection of a post and core system should satisfy many interrelated biologic, mechanical, and esthetic factors to optimally restore the endodontically treated tooth to adequate form and function. This review may serve as a guide to aid the clinician in the selection of a post-and-core system.

Changes caused by a mandibular removable partial denture opposing a maxillary complete denture

Abstract: Almost inevitable degenerative changes develop in the edentulous regions of wearers of complete upper and partial lower dentures. We have followed six patients over a three-year period with cephalometric radiographs to determine if these changes could be detected. In all six subjects, early changes that could become gross changes were apparent. In one of them degenerative clinical change is beginning to appear. This problem might be solved with treatment planning to avoid the combination of complete upper dentures against distal-extension partial lower dentures. The alternative of complete maxillary and mandibular dentures is not attractive to patients. Preserving posterior teeth to serve as abutments to support lower partial dentures and to provide a more stable occlusion is a better alternative. Ill-fitting dentures have been blamed for all of the lesions of the edentulous tissues, yet the most perfect denture will be ill-fitting after bone is lost from the anterior part of the ridge. Removable dentures need periodic attention at least as often as the natural teeth.

Biaxial flexural strength, elastic moduli, and x-ray diffraction characterization of three pressable all-ceramic materials.

Abstract: Statement of Problem. Before the release of an advanced ceramic material, independent assessment of its strength, elastic modulus, and phase composition is necessary for comparison with peer materials. Purpose. This study compared the biaxial flexural strength, elastic moduli, and crystalline phases of IPS Empress and Empress 2 with a new experimental ceramic. Material and Methods. Twenty standardized disc specimens (14 × 1.1 mm) per material were used to measure the biaxial strength. With a universal testing machine, each specimen was supported on 3 balls and loaded with a piston at a crosshead speed of 0.5 mm/min until fracture. Three standardized bars (30 × 12.75 × 1.1 mm) for each material were prepared and excited with an impulse tool. The resonant frequencies (Hz) of the bars were used to calculate the elastic moduli with the equation suggested by the standard ASTM (C 1259-94). X-ray diffraction with Cu Kα at a diffraction angle from 20 to 40 degrees was used to identify the crystalline phases by means of a diffractometer attached to computer software. The data were analyzed with 1-way analysis of variance followed by pairwise t tests ( P Results. Mean biaxial strengths were 175 ± 32, 407 ± 45, and 440 ± 55 MPa for IPS Empress, Empress 2, and the experimental ceramic, respectively. Elastic modulus results were 65, 103, and 91 GPa for the same materials, respectively. There was no significant difference in strength and elastic modulus between Empress 2 and the experimental ceramic. Both materials demonstrated a significantly higher elastic modulus and strength than IPS Empress. X-ray diffraction revealed leucite as the main crystalline phase for IPS Empress and lithium disilicate for both Empress 2 and the experimental ceramic. Conclusion. Within the limitations of this study, the improved mechanical properties of Empress 2 and experimental ceramic over those of IPS Empress were attributed to the nature and amount of their crystalline content lithium disilicate. (J Prosthet Dent 2003;89:347-80.)

In vitro marginal fit of three all-ceramic crown systems

Abstract: Statement of problem Studies on marginal discrepancies of single restorations using various systems and materials have resulted in statistical inferences that are ambiguous because of small sample sizes and limited numbers of measurements per specimen. Purpose The purpose of this study was to compare the marginal adaptation of single anterior restorations made using different systems. Material and methods The in vitro marginal discrepancies of 3 different all-ceramic crown systems (Celay In-Ceram, conventional In-Ceram, and IPS Empress 2 layering technique), and a control group of metal ceramic restorations were evaluated and compared by measuring the gap dimension between the crowns and the prepared tooth at the marginal opening. The crowns were made for 1 extracted maxillary central incisor prepared with a 1-mm shoulder margin and 6-degree tapered walls by milling. Thirty crowns per system were fabricated. Crown measurements were recorded with an optical microscope, with an accuracy of ±0.1 μm, at 50 points spaced approximately 400 μm along the circumferential margin. The criterion of 120 μm was used as the maximum clinically acceptable marginal gap. Mean gap dimensions and standard deviations were calculated for marginal opening. The data were analyzed with a 1-way analysis of variance (α=.05). Results Mean gap dimensions and standard deviations at the marginal opening for the incisor crowns were 87 ± 34 μm for control, 83 ± 33 μm for Celay In-Ceram, 112 ± 55 μm for conventional In-Ceram, and 46 ± 16 μm for the IPS Empress 2 layering technique. Significant differences were found among the crown groups (P Conclusion Within the limitations of this study, the marginal discrepancies were all within the clinically acceptable standard set at 120 μm. However, the IPS Empress 2 system showed the smallest and most homogeneous gap dimension, whereas the conventional In-Ceram system presented the largest and more variable gap dimension compared with the metal ceramic (control) restoration.

Anatomic crown width/length ratios of unworn and worn maxillary teeth in white subjects

Abstract: Statement of problem Dimensions of teeth have been available for a century. Some significant and clinically relevant aspects of dental esthetics, however, such as the crown width/length ratios, have not been presented in tooth morphology sources until recently. Purpose The purpose of this study was to analyze the anatomic crowns of 4 tooth groups (central incisors, lateral incisors, canines, and first premolars) of the maxillary dentition with respect to width, length and width/length ratios and determine how these parameters are influenced by the incisal edge wear. Material and methods Standardized digital images of 146 extracted human maxillary anterior teeth from white subjects (44 central incisors, 41 lateral incisors, 38 canines, 23 first premolars) were used to measure the widest mesiodistal portion “W” (in millimeters) and the longest inciso-cervical/occluso-cervical distance “L” (in millimeters). The width/length ratio “R” (%) was calculated for each tooth. A 1-way analysis of variance was used to compare the mean values of W, L, and R for the different groups (“unworn” and “worn” subgroups, except for premolars). Multiple least significant difference range tests (confidence level 95%) were then applied to determine which means differed statistically from others. Results There was no influence of the incisal wear on the average value of W (width) within the same tooth group. The widest crowns were those of central incisors (9.10 to 9.24 mm) > canines (7.90 to 8.06 mm) > lateral incisors (7.07 to 7.38 mm). Premolars (7.84 mm) had similar width as canines and worn lateral incisors. The L-value was logically influenced by incisal wear (worn teeth were shorter than unworn teeth) except for lateral incisors. The longest crowns were those of unworn central incisors (11.69 mm) > unworn canines (10.83 mm) and worn central incisors (10.67 mm) > worn canines (9.90), worn and unworn lateral incisors (9.34 to 9.55 mm), and premolars (9.33 mm). Width/length ratios also showed significant differences. The highest values were found for worn central incisors (87%) and premolars (84%). The latter were also similar to worn canines (81%), which constituted a homogeneous group with worn lateral incisors (79%) and unworn central incisors (78%). The lowest ratios were found for unworn canines and unworn lateral incisors (both showing 73%). Conclusions Along with other specific and objective parameters related to dental esthetics, average values for W (mesiodistal crown dimension), L (incisocervical crown dimension), and R (width/length ratio) given in this study for white subjects may serve as guidelines for treatment planning in restorative dentistry and periodontal surgery.

In vivo fracture resistance of implant-supported all-ceramic restorations.

Abstract: Statement of problem Because of their specific mechanical properties, all-ceramic restorations demonstrate a lower fracture resistance than ceramic restorations supported by metal substructures. However, advances have been made in the fabrication of high-strength all-ceramic abutments for anterior implants. No previous study has compared the fracture loads between 2 different all-ceramic abutments restored by glass-ceramic crowns. Purpose The purpose of this in vitro investigation was to quantify the fracture load of implanted-supported Al 2 O 3 and ZrO 2 abutments restored with glass-ceramic crowns. Material and methods Two ceramic abutments were tested: an Al 2 O 3 abutment (CerAdapt) and a ZrO 2 abutment (Wohlwend Innovative). The abutments (n = 10) were placed on Branemark dental implants and prepared for restoration with glass-ceramic crowns (IPS Empress). After fabrication, in accordance with the manufacturer's guidelines, the crowns were bonded to the all-ceramic abutments with a dual-polymerizing resin luting agent. The fracture loads (N) were determined by force application at an angle of 30 degrees by use of a computer-controlled universal testing device. The data were analyzed with the unpaired t test (α=.05). Results Statistical analysis showed significant differences between both groups ( P =.001) of all-ceramic abutments, with mean fracture load values of 280.1 N (± 103.1) for the Al 2 O 3 abutments and 737.6 N (± 245.0) for the ZrO 2 abutments. Conclusion Within the limitations of this study, both all-ceramic abutments exceeded the established values for maximum incisal forces reported in the literature (90 to 370 N). The ZrO 2 abutments were more than twice as resistant to fracture as the Al 2 O 3 -abutments.

Cytotoxicity of denture base acrylic resins: a literature review.

Abstract: Acrylic resins are widely used in the fabrication of denture bases and have been shown to be cytotoxic as a result of substances that leach from the resin. The primary eluate is residual monomer. Numerous reports suggest that residual monomer may be responsible for mucosal irritation and sensitization of tissues. This information is important, not only to assess the biologic effects of such materials, but also to enable a comparison among the different polymerization methods, thus assisting the clinician in selecting a material with minimal cytotoxicity. This article reviews the literature published from 1973 to 2000, selected by use of a Medline search, associated with cytotoxic effects usually ascribed to acrylic denture base materials.

The association between wear facets, bruxism, and severity of facial pain in patients with temporomandibular disorders.

Abstract: Statement of problem It is unclear whether patients with temporomandibular disorders (TMD) who report high levels of bruxism have more severe signs and symptoms of TMD and more advanced tooth wear than patients with TMD who report lower levels of bruxism. Purpose The purpose of this study was to determine whether there was a significant association between tooth wear, the parafunctional oral habit of bruxism, temporomandibular joint (TMJ) pain, and muscle pain severity in a TMD population. Material and methods A total of 84 subjects previously diagnosed with TMD, according to the Research Diagnostic Criteria for TMD (RDC/TMD) and who met 10 specific inclusion/exclusion criteria underwent a thorough multiaxial examination and classification recommended by the National Institute of Dental and Craniofacial Research (NIDCR). Measurement of tooth wear facets by use of a 4-point scale were graded in 10 zones on mandibular casts. One calibrated examiner performed all scoring. Bruxism was assessed in a standardized pretreatment questionnaire and in the dental history and interview (RDC/TMD) to indicate how frequently (0 = never to 3=very often) subjects performed a list of oral habits, which included bruxism. The Kappa reliability coefficient (range from: −1.0 to 1.0) was used to correct for chance agreement, and was computed for each of the 10 study sites designated for rating. Subjects were also compared for muscle and joint pain. Muscle pain was a summed measure derived from the dental examination findings (range 0 to 20), calculated from the presence or absence of pain induced by palpation of 20 predetermined muscle sites. Similarly, joint pain was a summed measure of the presence or absence of pain in the TMJs induced by palpation of the joints on the outer surface and in the external auditory canal in 5 different positions of the mandible. A Pearson product-moment correlation was used to compute the summed severity of tooth wear and the subjects' age. Analysis of covariance was used to determine whether the number of wear facets was significantly higher in patients with TMD who reported a history of bruxism, compared with patients with TMD who reported no or minimal bruxism, after controlling for the effect of age. Multivariate analysis of variance was used to determine whether the number of painful muscles of mastication and joint sites on standardized examination were significantly higher in patients with TMD with a history of bruxism (α=.05). Results In the population tested, tooth wear was modestly correlated with age ( r = .40, P Conclusions In this TMD population, tooth wear factors did not differentiate patients with bruxism from those without. The amount of bruxism activity was not associated with more severe muscle pain and was associated with less pain in the TMJ on palpation.

Effect of three bleaching agents on the surface properties of three different esthetic restorative materials

Abstract: Statement of problem Information related to the effect of night-guard vital bleaching procedure on the surface properties of esthetic dental restorative materials is incomplete. Purpose The aim of this study was to examine the effects of 3 proprietary carbamide peroxide bleaching agents on the surface properties of 3 dental esthetic restorative materials. Material and methods Three bleaching products (Nite White, Opalescence, and Rembrandt Lighten Gel) and 3 restorative materials (Duceram, Fuji II LC, and Silux Plus) were studied. A stainless steel mold and a 6-mm–thick polytetrafluoroethylene plate with a 1-cm–diameter hole were used to prepare 30 standardized specimens for each of the 3 restorative materials tested. Each group was divided into 3 subgroups (n=10). Two specimens from each subgroup were selected to form a control group. Three different carbamide peroxide bleaching agents were applied to each restorative material group for 8 hours per day for 30 days, respectively. Initial roughness measurements (Ra measured in μm) were made by use of a profilometer, at repeated intervals of 24 hours, 48 hours, 1, 2, 3, and 4 weeks (30 days). Surface topography of the specimens was assessed by scanning electron microscopy, and results were compared with the control group graphically. Surface structure and alterations of atomic weight percentages of element were made by use of energy-dispersive x-ray microanalysis. One-way analysis of variance was used to evaluate the surface roughness measurements. Significant results were evaluated with Fisher and Duncan's multiple range test ( P Result Surface roughness values for all restorative materials increased during the bleaching procedure. The only significant increase was found with the effect of Rembrandt bleaching gel on modified glass ionomer cement (mean Ra was 0.48 μm initially, 0.5 μm at 24 hours, 0.75 μm at 2 weeks, and 0.83 μm at 30 days). Surface roughness values increased significantly during the first 2 weeks ( P 2 content in the feldspathic porcelain and the microfilled composite groups for all bleaching agents. Modified glass ionomer specimens bleached with Nite White and Rembrandt showed an increase in mass percentage of SiO 2 , whereas Opalescence specimens showed a decrease. However, there were no significant differences between the groups. Conclusion Within the limitations of this study, no significant difference was found between bleaching agents. Most changes occurred in the first 2 weeks; the products tested were relatively stable in the following test periods. No significant change in the surface roughness of feldspathic porcelain was observed. On the other hand, the microfilled composite tested showed slight changes in the surface roughness. Significant changes were found for the modified glass ionomer cement ( P >.005).

Finite element analysis to determine implant preload

Abstract: Statement of problem The nature of the forces used to clamp implant components together, and how they are generated and sustained, is lacking in the literature. Purpose This study examined the dynamic nature of developing the preload in an implant complex using finite element analysis. Methods The implant complex was modeled in accordance with the geometric designs for the Nobel Biocare implant systems. A thread helix design for the abutment screw and implant screw bore was modeled to create the geometric design for these units of the implant systems. Using the software programs HyperWorks and LS3D-Dyna, 2 3-dimensional finite element models of (1) a Branemark System 3.75 × 10-mm titanium Mark III implant, a CeraOne titanium abutment, a Unigrip gold alloy abutment screw, and (2) a Replace Select System 4.30 × 10-mm titanium implant, a Straight Esthetic titanium abutment, and a TorqTite titanium abutment screw were created. Modeling the threads to the machining specifications permitted simulation of screw tightening. The abutment screws were subjected to a tightening torque in increments of 1 Ncm from 0 to 64 Ncm using ABAQUS software. Using these models, the effect of the coefficient of friction on the development of preload amount in the implant complex during and after abutment screw tightening was determined. In the first experiment, the coefficient of friction was set to 0.20 between the titanium bearing surface of the abutments and the implant bearing surfaces, and 0.26 between the gold abutment screw and the titanium implant screw bore. In the second experiment, the coefficient of friction was varied; the titanium implant and titanium abutment bearing surfaces were set to a coefficient of friction of 0.20, whereas the Mark III gold and the Replace Select titanium abutment screws and their respective titanium screw bores in the implants were set to 0.12. The preload amount (N) was determined from the finite element analysis. Results The stress distribution pattern clearly demonstrated a transfer of preload force from the screw to the implant during tightening. A preload of 75% of the yield strength of the abutment screw was not established using the recommended tightening torques. Conclusion Using finite element analysis, a torque of 32 Ncm applied to the abutment screws in the implant assemblies studied in the presence of a coefficient of friction of 0.26 resulted in a lower than optimum preload for the abutment screws. To reach the desired preload of 75% of the yield strength, using a torque of 32 Ncm applied to the abutment screws in the implant assemblies studied, the coefficient of friction between the implant components should be 0.12.

The influence of porcelain layer thickness on the final shade of ceramic restorations.

Abstract: Statement of problem. Ceramic restorations should be made of porcelain layers of different opacity, shade, and thickness in order to provide a natural appearance. By means of CAD/CAM layering technology such as CICERO, it is feasible to produce all-ceramic crowns with porcelain layers of predetermined thickness. However, it is not yet known whether changes in thickness of these porcelain layers within the clinically available space can perceivably influence the overall shade of the restoration. Purpose. The purpose of this study was to determine, quantitatively, the effect of different thickness ratios of opaque porcelain (OP) and translucent porcelain (TP) layers on the overall shade of all-ceramic specimens. Material and Methods. The CIELAB values of 5 assembled specimens, each consisting of 2 or 3 discs (CORE 0.70 mm/OP - 0, 0.25, 0.50, 0.75, or 1.00 mm/TP 1.00, 0.75, 0.50, 0.25, or 0 mm) were determined with a spectrophotometer for the Vita shades A1, A2, and A3. Distilled water was used to attain optical contact between the layers. Black or white backgrounds were used to assess the influence of the background on the final shade. Color differences (E) between layered specimens were determined. Correlation between the thickness ratio and the L*, a*, and b* values was calculated by 2-tailed Spearman correlation analysis. Results. The results indicated that small changes in OP/TP thickness ratio can perceivably influence the final shade of the layered specimens (E 1). Redness a* and yellowness b* increased with the thickness of OP for all shades. Redness a* (P .01 for all shades) correlated more strongly with thickness than yellowness b* (P .01 for A1 and A3; P .05 for A2). The lightness (L*) was shade dependent. The correlation (r) between OP/TP thickness and L* was 0.975 (P .01) for shade A1, 0.700 (not statistically significant) for shade A2, and 0.900 (P .05) for shade A3. Conclusion. Small changes in thickness and shade of opaque and translucent porcelain layers can influence the final shade of the layered porcelain specimen. (J Prosthet Dent 2003;90:563-70.)

Evaluation of the accuracy of three techniques used for multiple implant abutment impressions

Abstract: Statement of problem. Movement of pick-up type impression copings inside the impression material during clinical and laboratory phases may cause inaccuracy in transferring the spatial position of implants from the oral cavity to the master cast. As a consequence, the laboratory technician may fabricate a restoration that requires corrective procedures. Purpose. This in vitro study evaluated the accuracy of 3 different impression techniques using polyether impression material to obtain a master cast for the fabrication of a prosthesis that would fit passively on multiple implants. Material and Methods. A machined metal model with 6 implants and abutments and a corresponding, passively fitting, matching metal template were fabricated. A total of 45 medium-consistency polyether impressions (Impregum Penta) of this model were made with pick-up type square impression copings. Three groups of 15 each were made with different impression techniques: in group 1, nonmodified square impression copings were used; in group 2, square impression copings were used and joined together with autopolymerizing acrylic resin before the impression procedure; and in group 3, square impression copings previously airborne particle-abraded and coated with the manufacturer-recommended impression adhesive were used. The matching metal template, which had been passively fit to the metal model so that it encountered no visually perceptible resistance or rocking on the abutments, was used as the control for evaluation of the accuracy of passive fit. A single calibrated and blinded examiner visually evaluated each cast. Positional accuracy of the abutments was numerically assessed with an optical scanner at original magnification × 10, which provided measurements to within 2 μm of the variations of the casts with respect to the horizontal distances between the 2 most posterior abutments and the 2 most anterior abutments. Data were analyzed with a 1-way analysis of variance at α=.05, followed by the Student Newman-Keuls method ( P =.05). Results. Visual examination of the casts from group 1 revealed discrepancies between 1 or more abutments and the metal template. Visual analysis of the master casts from groups 2 and 3 revealed close alignment of the metal template on all 6 abutments. One-way analysis of variance analyzed the numerical data obtained with the optical scanner and revealed significant differences among the 3 impression techniques ( P P =.05). The distance between abutments 1 and 6 compared to the standard metal model was 33.83 μm (SD ± 5.4) greater on group 2 casts, 31.72 μm (SD ± 4.6) greater on group 3 casts, and 78.16 μm (SD ± 22.14) greater on group 1 casts. Distances between the most anterior abutments were also greater than those recorded on the metal model. The distance was 31.42 μm (SD ± 7.6) greater on group 2 casts, 30.34 μm (SD ± 6.4) greater on group 3 casts, and 67.91 μm (SD ± 15.34) greater on group 1 casts. Conclusion. Within the limitations of this study, improved accuracy of the master cast was achieved when the impression technique involved square impression copings joined together with autopolymerizing acrylic resin or square impression copings that had been airborne particle-abraded and adhesive-coated. (J Prosthet Dent 2003;89:186-92.)

Effects of post-core design and ferrule on fracture resistance of endodontically treated maxillary central incisors.

Abstract: Statement of Problem. Studies concerning the effects of post-core design and ferrule on the fracture resistance of endodontically treated teeth remain controversial. Purpose. The purpose of this study was to investigate in vitro the effects of post-core design and ferrule on the fracture resistance of root canal treated human maxillary central incisors restored with metal ceramic crowns. Material and Methods. Forty-eight extracted human maxillary central incisors were endodontically treated and divided into 4 groups of 12. The following treatments were evaluated: group A: restored with metal ceramic (porcelain fused to metal [PFM]) crowns as control; group B: 2-mm ferrule/custom cast post-core/PFM crowns; group C: no ferrule/custom cast post-core/PFM crowns; and group D: 2-mm ferrule/prefabricated post and resin core/PFM crowns. Each specimen was subjected to load (N) on the lingual surface at a 135-degree angle to the long axis with a MTS 810 material testing machine until fracture at a crosshead speed of 0.02 cm/min. One-way analysis of variance and nonparametric chi-square test were used to compare the results. A significant analysis of variance result was followed by Newman-Keuls pairwise multiple comparisons ( P Results. There were significant differences among the 4 groups studied ( P Conclusion. Within the limitations of this study, not all of the post-core structures tested improved the strength of the endodontically treated teeth. Those prepared with a 2-mm dentin ferrule more effectively enhanced the fracture strength of custom cast post-core restored endodontically treated maxillary central incisors. (J Prosthet Dent 2003;89:368-73.)

Comparison of fracture tests of denture base materials

Abstract: Statement of problem Clinical studies have shown midline fracture to be a common problem in dentures. In order to evaluate the resistance of denture base resins against fracture, not only impact strength measurements but also fracture toughness tests should be performed. Purpose The aim of this study was to determine the fracture toughness of denture base resins and to compare the results with impact strength measurements. Materials and methods Seven heat-polymerized denture base resins were chosen for the study: 5 high impact (GC Luxon, Injectall IPF HI-I, Ivocap Plus, Lucitone 199, and Trevalon HI) and 2 conventional (Major Base 2 and Probase Hot). Three series of 12 specimens were used for the Charpy impact test (specimen dimensions: 80 × 10 × 4 mm, notch depth: 2 mm) and 2 Izod impact tests (specimen dimensions: 50 × 6 × 4 mm; notch depth: 1.2 mm for the first series, 3.4 mm for the second series). The maximum stress intensity factor (K I,max ) (MPa · m 1/2 ) and the work of fracture (WOF) (kJ/m 2 ) were measured for 8 specimens in a fracture toughness test (specimen dimensions: 40 × 8 × 4; notch depth: 3.2 to 3.3 mm). A 1-way ANOVA with a post-hoc Tukey-Kramer test (α=.05) was used to compare the data. Results The results achieved by the different materials and the rankings varied, depending on which parameter was considered. For example, the 1.2-mm Izod impact strength of Ivocap Plus (2.49 ± 0.24 kJ/m 2 ) was not significantly different from GC Luxon (2.64 ± 0.15 kJ/m 2 ) and significantly higher than Major Base 2 (1.99 ± 0.23 kJ/m 2 ) and Probase Hot (1.79 ± 0.20 kJ/m 2 ) ( P 2 ) was almost half the value of GC Luxon (2.85 ± 0.05 kJ/m 2 ) and not significantly different from Major Base 2 (1.36 ± 0.03 kJ/m 2 ) and Probase Hot (1.36 ± 0.09 kJ/m 2 ). In the fracture toughness test, the K I,max values of GC Luxon (2.63 ± 0.09 MPa · m 1/2 ), Lucitone 199 (2.53 ± 0.08 MPa · m 1/2 ), Trevalon HI (2.56 ± 0.13 MPa·m 1/2 ), and Ivocap Plus (2.41 ± 0.04 MPa · m 1/2 ) were not significantly different. Among all parameters, the WOF value appeared to be the test that allowed a clear differentiation between the products, placing Probase Hot (0.27 ± 0.03 kJ/m 2 ) and Major Base 2 (0.38 ± 0.03 kJ/m 2 ) on a low level, Injectall IPF HI-I (0.63 ± 0.17 kJ/m 2 ) on an intermediate level, Ivocap Plus (1.12 ± 0.06 kJ/m 2 ) on a medium-high level, and Lucitone 199 (1.41 ± 0.06 kJ/m 2 ), GC Luxon (1.50 ± 0.17 kJ/m 2 ), and Trevalon HI (1.58 ± 0.07 kJ/m 2 ) on a high level. Conclusion Specimen geometry and testing configuration influenced the impact strength measurements. The fracture toughness method seems to be more suitable than impact strength measurements to demonstrate the effects of resin modifications. The differences between conventional and so-called "high-impact" denture base resins are more clearly demonstrated with fracture toughness measurements.

Intrarater repeatability of shade selections with two shade guides

Abstract: Statement of problem. Color research has shown that shade guides do not always represent the color of natural teeth. Moreover, visual evaluation has been found to be unreliable and inconsistent. Purpose. This investigation evaluated the effects of 2 shade guides on the intrarater repeatability (reliability) of prosthodontists and general practitioners with regard to shade selection. Material and methods. Ten prosthodontists and ten general practitioners (all men, 35-45 years old) with an average practice experience of 14 years participated in this study. Examiners were tested to eliminate color blindness. Each clinician used Vita Lumin Vacuum and Vitapan 3D-Master shade guides to determine the shades of the maxillary right canines of 20 patients following a standard protocol. The identification codes of the shade tabs were masked to prevent shade memory. All teeth were polished before each shade selection, and the selection process was standardized for controlled lighting and procedures. Shade selections were randomly repeated 1 month later by the same practitioners on the same group of patients in accordance with the same shade-selection protocol. Analysis of variance and t tests for individual comparisons among means were performed ( P Results. Significant interactions were found between the effects of shade guide system and specialty training on intrarater repeatability ( P P t test). Use of the Vitapan 3D-Master shade guide significantly improved the intrarater repeatability of general practitioners compared with the Vita Lumin Vacuum shade guide ( P P =.2861). Conclusion. Within the limitations of this study, the prosthodontists demonstrated superior intrarater repeatability in shade selection, especially when the Vita Lumin Vacuum shade guide was used. Use of the Vitapan 3D-Master shade guide notably improved intrarater repeatability among the general practitioners. (J Prosthet Dent 2003;89:50-3.)

Finite element analysis of stresses in molars during clenching and mastication.

Abstract: Statement of problem During physiological functions of the masticatory system such as swallowing and chewing, teeth are subjected to variations in force application. Most in vitro analyses of stress have not analyzed the combined forces acting on teeth. Purpose The purpose of this study was to analyze the stresses induced in a mandibular molar during clenching and chewing of morsels with various elastic moduli. Materials and methods The investigation was performed by means of finite element analysis with the use of contact elements. Two-dimensional models of the mandibular first molar and the crown of the opposing maxillary molar were created. The computerized simulation evaluated the clenching and chewing of 4 morsels with different elastic moduli (similar to hard gum, tough meat, bone, and combination of hard gum and bone). The movement of the studied teeth was simulated in the frontal plane. Teeth models crushed morsels and closed into the maximal intercuspation position. The values of stresses in the mandibular molar were calculated during these situations. Results The study revealed that clenching of molars and chewing morsels of high elastic moduli resulted in maximal equivalent stresses within occlusal enamel. During mastication of morsels of low elastic moduli the stress concentration was located in the cervical region of the lingual side of the mandibular molar. Masticating a low-elasticity morsel containing a fragment of bone caused the highest equivalent stresses in the lingual wall and high tensile stresses in enamel near the central intercuspal fissure of the tooth studied. Conclusion During mastication of various morsels, maximal equivalent stresses occurred in occlusal enamel and in the cervical region of the lingual wall of the first mandibular molar. The more unfavorable and highest stresses were exerted during mastication of nonhomogeneous morsels.

The influence of the veneering porcelain and different surface treatments on the biaxial flexural strength of a heat pressed ceramic

Abstract: Statement of problem The strength of all-ceramic restorations can be adversely affected by surface defects, leading to restoration failures. Additionally, when a 2-layer all-ceramic restoration is required for esthetic purposes, part of the stronger ceramic core material is replaced by veneering porcelain. Purpose This study evaluated the effect of different surface treatments on the strength of a ceramic core material and veneering porcelain, as well as the influence of veneering porcelain on the strength of a 2-layer ceramic structure. Material and methods Fifty heat-pressed ceramic cores and 30 veneering porcelain discs (17 mm diameter × 2 mm) were made. From the ceramic core group, 20 discs were selected and reduced to a thickness of 1 mm and veneered with 1 mm of porcelain. These specimens were divided into 2 groups of 10 each. The remaining 30 ceramic core and the 30 veneering porcelain discs were divided into 2 sets of 3 equal sized groups (n=10). Ceramic core groups were prepared for testing having the following surfaces: airborne-particle abrasion, ground, and overglazed. Veneering porcelain groups were tested: as fired (no additional treatment), ground, and overglazed. Biaxial flexural strength was measured using the ball-on-ring test method. All specimens were loaded to fracture. One and 2-way analysis of variance were used to analyze the data (α=.05). Results The ceramic core discs were significantly ( P =.001) stronger than the veneering porcelain discs for the airborne-particle abrasion, as-fired, and ground surface treatments (82 ± 11 MPa vs 51 ± 8 MPa and 93 ± 14 MPa vs 60 ± 6 MPa, respectively). For the overglazed treatment, there was not a significant difference between the core (115 ± 1 4 MPa) and the veneer materials (107 ± 14 MPa). The ground 1-layer core was significantly ( P =.015) stronger (93 ± 14 MPa) than the 2-layer with the core tested in tension (72 ± 19 MPa). There was no significant difference between 1-layer veneer overglazed (107 ± 14 MPa) and 2-layer discs when tested with the veneer in tension (105 ± 16 MPa). Conclusion The overglazed surface treatment significantly improved the strength of the materials tested, as well as the strength of 2-layer discs with the veneer in tension. The veneering porcelain influenced the strength of 2-layer specimens only when tested with the ground ceramic core surface in tension.

The retention of complete crowns prepared with three different tapers and luted with four different cements

Abstract: Statement of problem The role of adhesive properties of cements on the retentive strength of crowns with different degrees of taper is not clear. Purpose This study evaluated the retention of full crowns prepared with 3 different tapers and cemented with 2 conventional and 2 adhesive resin cements. Material and methods One hundred twenty sound human molar teeth were assigned randomly to 1 of 12 groups, (n=10). The groups represented the 4 cements: zinc phosphate (Fleck's), a conventional glass ionomer (Ketac-Cem); 2 adhesive resin cements (CB and 3 tapers of 6-degrees, 12-degrees, and 24-degrees within each cement. Crowns were cast with a high noble alloy. The 6-degree taper was considered the control within each cement group. Retention was measured (MPa) by separating the metal crowns from the prepared teeth under tension on a universal testing machine. Analysis of variance was used to test the main effects on the retentive strength of full crowns, namely cements, tapers, and failure modes. The Fisher's multiple comparison test was used to evaluate the source of the differences. The χ 2 analyses were used to examine the relationships between failure types, cements, and tapers. All statistical tests were conducted at α=.05. Results There was a significant difference in the main effect cement ( P P =.0002). The mean retentive strength values of both Fleck's and Ketac-Cem were significantly lower than the mean retentive strength values of both C&B Metabond and Panavia ( P P =.0666). The difference in retention was significant between the 6-degree taper and the 24-degree taper ( P P =.0178). The types of failure were adhesive in the cement (65%), cohesive in the tooth (31%), and assembly failure (fracture of embedding resin) (4%). The type of failure was dependent on the degree of taper ( P P Conclusion Within the limitations of this study, the retentive values of the adhesive resins at 24-degree taper were 20% higher than the retentive values of the conventional cements at 6-degree taper. The use of resin luting agents yielded retention values that were double the values of zinc phosphate or conventional glass ionomer cement.

Preparation design and margin distortion in porcelain-fused-to-metal restorations

Abstract: The relationship between preparation finish line configurations and marginal stability of porcelain-fused-to-metal restorations during the firing cycle was studied Four labial finish lines presently in use were examined The shoulder finish lines, with and without a bevel, were found to produce significantly less distortion in labial margins of porcelain-fused-to-metal restorations than do chamfer finish lines with and without a bevel

The effect of current bleaching agents on the color of light-polymerized composites in vitro.

Abstract: Statement of problem Bleaching agents may affect the color of existing composite restorations. Purpose The purpose of this study was to compare the effect of 10% carbamide peroxide and 10% hydrogen peroxide on the color of light-polymerized hybrid, macrofilled, and polyacid-modified composites. Material and methods Two light-polymerized hybrid composites (3M Valux and Spectrum TPH), 1 macrofilled condensable composite (Solitaire), and 2 polyacid-modified composites (Dyract AP and Compoglass) were used. The hybrid composites served as controls. The color of 8 specimens of each material was analyzed by use of a spectrophotometer before bleaching. The specimens were then divided randomly into 2 subgroups (n=4). One group was immersed in 10% carbamide peroxide solution and the other in 10% hydrogen peroxide, for 8 hours each for 14 consecutive days. After bleaching, color changes (Δ E) were determined for each material and compared by use of the Kruskal-Wallis test, followed by the Mann-Whitney U test ( P Results After bleaching with carbamide peroxide, the color changes (ΔE) for Dyract AP (2.18; SD=1.41), Compoglass (1.14; SD=0.26) and Solitaire (1.56; SD=0.89) were higher than the color changes recorded for 3M Valux (0.63; SD=3.60), and Spectrum TPH (0.66; SD=1.24). The differences between materials bleached with carbamide peroxide were not statistically significant. After bleaching with hydrogen peroxide, the color changes for Dyract AP (9.39; SD=0.53) and Compoglass (5.15; SD=0.52) were higher than the changes recorded for Spectrum TPH (4.53; SD=1.53) and 3M Valux (3.41; SD=4.40), whereas the color change of Solitaire (3.69; SD=0.57) was significantly higher than that of 3M Valux ( P =.01). The color changes for all restorative materials tested were clinically detectable after the application of 10% hydrogen peroxide. However, clinically noticeable discoloration was observed only for Dyract AP treated with 10% carbamide peroxide. Conclusion In comparison to 10% carbamide peroxide, 10% hydrogen peroxide caused more color changes in the composites tested.

Accuracy of open tray implant impressions: an in vitro comparison of stock versus custom trays.

Abstract: Statement of Problem. The accuracy of an implant fixture-level impression is affected by the type of impression tray used. Purpose. The purpose of this in vitro study was to investigate the accuracy of open tray implant impressions comparing polycarbonate stock impression trays and rigid custom-made impression trays to make implant fixture-level impressions. Material and Methods. Gold cylinder pairs, splinted by gold bars (reference frameworks) were constructed on an aluminum typodont. Polyether impressions were made of 2 pairs of Branemark 3.75-mm diameter fixtures mounted in an aluminium typodont, with 3 stock impression trays, 3 close-fit custom trays, and 3 spaced custom impression trays, by use of an open tray technique. The casts produced were assessed for accuracy by attaching the reference frameworks with alternate single screws and measuring the vertical fit discrepancy of these reference frameworks to the analogs within the working cast using a traveling microscope. Comparison of gap dimensions by tray type was performed with a nonparametric Kruskal-Wallis analysis of variance (ANOVA) followed by pair-wise Mann-Whitney U tests. To adjust for multiple comparisons in the post-ANOVA contrasts ( P P Results. The results showed that the mean fit accuracy, as measured by vertical fit discrepancy, of casts from the stock trays (23 ± 20 μm) were statistically significantly less ( P Conclusion. Within the limits of this in vitro study, rigid custom trays produced significantly more accurate impressions than the polycarbonate stock trays. The stock trays used in this study could not produce accurate impressions consistently. For analogs with a 20-mm separation, there was a difference in medians of 10 μm in accuracy between the stock and custom trays. (J Prosthet Dent 2003;89:250-5.)

Fracture resistance of prepared teeth restored with bonded inlay restorations.

Abstract: Statement of problem Tooth preparation weakens the remaining tooth structure. Purpose This study attempted to measure and compare the strength of intact, prepared, and restored human maxillary premolars. Material and methods Fifty intact, noncarious human maxillary premolars were divided into 5 groups of 10 and were mounted with their roots imbedded in autopolymerized acrylic. In the first group, the teeth were intact with no preparation. In the other 4 groups, Class II MOD preparations were made with a water-cooled high-speed hand piece. In 1 group, the cavity preparations were restored with bonded CAD/CAM ceramic inlays. In 2 groups, the preparations were restored with bonded CAD/CAM composite inlays (acid etched or air particle abraded). In the final group, the teeth were prepared but unrestored. Specimens were tested individually in a universal testing machine, in which a 4.82-mm-diameter steel sphere plunger was mounted in the crosshead moving at 0.5 mm/min. The plunger contacted the facial and lingual triangular ridges beyond the margins of the restorations. Peak load to fracture (N) was measured for each specimen. Means were calculated and analyzed with analysis of variance ( P ≤.05). Results MOD preparations weakened the teeth by approximately 59%. Restoring the teeth with ceramic or composite inlays did not significantly strengthen the teeth under this testing system. Of the restored teeth, those restored with indirect composite inlays cemented following manufacturer's recommendations had the highest fracture resistance. Conclusion Within the limitations of this study, under static compression load testing, bonded inlay restorations did not strengthen maxillary premolars with large MOD preparations.