Showing papers on "Osseointegration published in 1998"

Biological factors contributing to failures of osseointegrated oral implants, (II). Etiopathogenesis

Abstract: The aim of the present review is to evaluate the English language literature regarding factors associated with the loss of oral implants. An evidence-based format in conjunction, when possible, with a meta-analytic approach is used. The review identifies the following factors to be associated with biological failures of oral implants: medical status of the patient, smoking, bone quality, bone grafting, irradiation therapy, parafunctions, operator experience, degree of surgical trauma, bacterial contamination, lack of preoperative antibiotics, immediate loading, nonsubmerged procedure, number of implants supporting a prosthesis, implant surface characteristics and design. Excessive surgical trauma together with an impaired healing ability, premature loading and infection are likely to be the most common causes of early implant losses. Whereas progressive chronic marginal infection (peri-implantitis) and overload in conjunction with the host characteristics are the major etiological agents causing late failures. Furthermore, it appears that implant surface properties (roughness and type of coating) may influence the failure pattern. Various surface properties may therefore be indicated for different anatomical and host conditions. Finally, the histopathology of implant losses is described and discussed in relation to the clinical findings.

Assessment of implant stability as a prognostic determinant.

Abstract: PURPOSE This paper aims to establish the parameters necessary to monitor successful implant placement and osseointegration. RESULTS AND DISCUSSION Implant stability is considered to play a major role in the success of osseointegration. Primary implant stability at placement is a mechanical phenomenon that is related to the local bone quality and quantity, the type of implant and placement technique used. Secondary implant stability is the increase in stability attributable to bone formation and remodeling at the implant/tissue interface and in the surrounding bone. Techniques for measuring implant stability and osseointegration, including the clinical measurement of cutting resistance during implant placement and removal torque following osseointegration, are discussed. Nondestructive test methods, including impact-based techniques such as the Periotest and the Dental Fine Tester, are also discussed. An alternative method, resonance frequency analysis, is described in detail. CONCLUSION It is clear that stability both at placement and during function is an important criterion for the success of dental implants. Quantitative methods, including resonance frequency analysis, can yield valuable information.

Timing of loading and effect of micromotion on bone-dental implant interface: review of experimental literature

Abstract: A significant no-load healing period is the generally accepted prerequisite for osseointegration in dental implantology. The aim of this article was to examine whether this no-load healing period is validated by the experimental literature. In vivo histological data was scrutinized to identify the effect of early loading protocols on the bone-implant interface. Several loading modes were identified. They were categorized into groups according to implant design and the type of prosthetic reconstruction, and by their ability to introduce a distinct magnitude of motion at the interface. Specific histologic responses of early loaded implants (i.e., fibrous repair or osseointegration) were suggested to be directly related to the specific combinations of the above parameters. Early loading per se was not found to be detrimental to osseointegration. Specifically, only excessive micromotion was directly implicated in the formation of fibrous encapsulation. The literature suggests that there is a critical threshold of micromotion above which fibrous encapsulation prevails over osseointegration. This critical level, however, was not zero micromotion as generally interpreted. Instead, the tolerated micromotion threshold was found to lie somewhere between 50 and 150 microns. Suggestions are made for the earliest loading time that achieves osseointegration.

Mechanisms of endosseous integration.

Abstract: UNLABELLED Although the clinical term "osseointegration" describes the anchorage of endosseous implants to withstand functional loading, it provides no insight into the mechanisms of bony healing around such implants. Nevertheless, an understanding of the sequence of bone healing events around endosseous implants is believed to be critical in developing biologic design criteria for implant surfaces. RESULTS AND DISCUSSION This discussion paper shows that peri-implant bone healing, which results in contact osteogenesis (bone growth on the implant surface), can be phenomenologically subdivided into three distinct phases that can be addressed experimentally. The first, osteoconduction, relies on the migration of differentiating osteogenic cells to the implant surface, through a temporary connective tissue scaffold. Anchorage of this scaffold to the implant surface is a function of implant surface design. The second, de novo bone formation, results in a mineralized interfacial matrix, equivalent to that seen in cement lines in natural bone tissue, being laid down on the implant surface. Implant surface topography will determine if the interfacial bone formed is bonded to the implant. A third tissue response, that of bone remodeling, will also, at discrete sites, create a bone-implant interface comprising de novo bone formation. CONCLUSION Treatment outcomes in dental implantology will be critically dependent on implant surface designs that optimize the biologic response during each of these three distinct integration mechanisms.

Bone response to unloaded and loaded titanium implants with a sandblasted and acid-etched surface : A histometric study in the canine mandible

Abstract: Many dental clinical implant studies have fo- cused on the success of endosseous implants with a variety of surface characteristics. Most of the surface alterations have been aimed at achieving greater bone-to-implant con- tact as determined histometrically at the light microscopic level. A previous investigation in non-oral bone under short- term healing periods (3 and 6 weeks) indicated that a sand- blasted and acid-etched titanium (SLA) implant had a greater bone-to-implant contact than did a comparably- shaped implant with a titanium plasma-sprayed (TPS) sur- face. In this canine mandible study, nonsubmerged implants with a SLA surface were compared to TPS-coated implants under loaded and nonloaded conditions for up to 15 months. Six foxhound dogs had 69 implants placed in an alternating pattern with six implants placed bilaterally in each dog. Gold crowns that mimicked the natural occlusion were fabricated for four dogs. Histometric analysis of bone contact with the implants was made for two dogs after 3 months of healing (unloaded group), 6 months of healing (3 months loaded), and after 15 months of healing (12 months loaded). The SLA implants had a significantly higher (p < 0.001) percentage of bone-to-implant contact than did the TPS implants after 3 months of healing (72.33 ± 7.16 versus 52.15 ± 9.19; mean ± SD). After 3 months of loading (6 months of healing) no significant difference was found be- tween the SLA and TPS surfaced implants (68.21 ± 10.44 and 78.18 ± 6.81, respectively). After 12 months of loading (15 months of healing) the SLA implants had a significantly greater percentage (p < 0.001) of bone-to-implant contact than did the TPS implants (71.68 ± 6.64 and 58.88 ± 4.62, respectively). No qualitative differences in bone tissue were observed between the two groups of implants nor was there any difference between the implants at the clinical level. These results are consistent with earlier studies on SLA im- plants and suggest that this surface promotes greater osse- ous contact at earlier time points compared to TPS-coated implants. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 1-11, 1998.

Evaluating Parameters of Osseointegrated Dental Implants Using Finite Element AnalysisA Two-Dimensional Comparative Study Examining the Effects of Implant Diameter, Implant Shape, and Load Direction

Abstract: Finite element analysis (FEA) has been proven to be a precise and applicable method for evaluating dental implant systems. By means of FEA, a parasaggital model was digitized from a computed tomography (CT)-generated patient data set, and various single-tooth, osseointegrated, two-dimensional dental implant models were simulated. The specific aims of the study were to: (1) examine the effect of implant diameter variation (3.8 mm–6.5 mm) of both a press-fit, stepped cylindrical implant type and a press-fit, straight cylindrical implant type as osseointegrated in the posterior mandible; (2) compare the stress-dissipating characteristics of the stepped implant versus the straight implant design; and (3) analyze the significance of bite force direction (vertical, horizontal, and oblique 45°) on both implant types. The results of the FEA suggested that (1) using the widest diameter implant is not necessarily the best choice when considering stress distribution to surrounding bone, but within certain m...

Surgical determinants of clinical success of osseointegrated oral implants: a review of the literature.

Abstract: PURPOSE This article reviews the current knowledge about the influence of surgical factors on implant failure in routine cases and in those where implants have been used in conjunction with bone augmentation procedures. MATERIALS AND METHODS Clinical reports published in major scientific journals served as the basis for this review. RESULTS With few exceptions, most clinical reports were on screw-shaped titanium implants. High failure rates are associated with poor bone quality and the use of short implants in the athrophic maxilla, irradiation, and bone-grafting procedures of the athrophic maxilla. Evidence for high long-term failure rates of press-fit cylinders was found. Moreover, limited clinical experience, lack of preoperative antibiotics, and smoking may lead to higher failure rates. CONCLUSION There is a need for further research to increase the success rates in the severely resorbed maxilla. Because of a lack of proper documentation with respect to the great majority of currently used oral implant designs, the influence of different factors and their long-term results remain unknown.

The influence of controlled occlusal overload on peri-implant tissue. part 4: a histologic study in monkeys.

Abstract: This study examined the influence of controlled occlusal overload on an implant. An experiment was conducted on five crab-eating monkeys (Macaca fascicularis) in which overload with no inflammation in the peri-implant tissues was modeled. Two osseointegrated implants were placed into each monkey. After 3 months of osseointegration, superstructures that were excessive by about 100 microns were mounted on the implants, and a traumatic occlusal force was experimentally delivered to its implant from the lingual to the buccal side. This procedure was performed under conditions of good oral hygiene. The monkeys received an excessive occlusal force for 1 to 4 weeks and were then immediately sacrificed. The results showed that the implants remained firmly integrated with bone, and all of the subjects that received excessive occlusal force for 1 to 4 weeks showed an absence of gross bone loss. These results suggest that conditions of occlusal force created by excessively high implant-supported superstructures may not destroy the peri-implant tissues.

Implant-supported overdentures: a longitudinal prospective study.

Abstract: The aim of this study was to evaluate the clinical function and long-term prognosis of overdentures retained by a small number of implants in the maxilla and mandible using one of two different attachment systems. Included in the study were all patients referred to specialty clinics in Jonkoping and Linkoping, Sweden, during the treatment period who needed an overdenture and could be provided with a minimum number of two bilaterally-placed implants. Excluded were patients with bone-grafted jaws, irradiated cancer patients, heavy bruxers, and patients who had lost a fixed prosthesis because of implant losses. The patients were randomly assigned to receive one retentive system, either a round 2-mm-diameter bar with clips or ball attachments (Nobel Biocare). Eighteen overdentures were placed in maxillae and 32 in mandibles, supported by a total of 115 Branemark implants. Of the implants placed, 86.1% were continuously osseointegrated. The cumulative implant survival rates after 7 years of loading were 75.4% in the maxillae and 100% in the mandibles. There was no difference in implant survival rate between the attachment systems. Patients with implant losses were characterized by severely resorbed maxillary ridges and inferior bone quality, together with unfavorable loading circumstances such as short implants combined with long leverages. Complications and prosthetic adjustments were mostly resolved early and easily.

Removal Torque Values of Titanium Implants in the Maxilla of Miniature Pigs

Abstract: The purpose of this study was to compare side-by-side two different titanium screw-type implants in the maxillae of miniature pigs. The test implants had a machined and acid-etched surface (Osseotite) whereas the control implants were sandblasted and acid-etched (SLA). After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the shear strength of the bone-implant interface for both implant types. The results demonstrated significant differences between both implant types (P < .01). Osseotite implants revealed mean removal torque values (RTV) of 62.5 Ncm at 4 weeks, 87.6 Ncm at 8 weeks, and 95.7 Ncm at 12 weeks of healing. In contrast, the SLA implants demonstrated mean RTV of 109.6 Ncm, 196.7 Ncm, and 186.8 Ncm at corresponding healing periods. The mean RTV for SLA implants was 75% to 125% higher than for Osseotite implants up to 3 months of healing.

The influence of bone mechanical properties and implant fixation upon bone loading around oral implants.

Abstract: Finite element models were created to study the stress and strain distribution around a solitary Branemark implant. The influence of a number of clinically relevant parameters was examined: bone-implant interface (fixed bond versus frictionless free contact), bone elastic properties, unicortical versus bicortical implant fixation and the presence of a lamina dura. Bone loading patterns in the vicinity of the implant seem to be very sensitive to these parameters. Hence they should be integrated correctly in numerical models of in vivo behaviour of oral implants. This necessitates the creation of patient-dependent finite element models.

Immediate Loading of Titanium Plasma-Sprayed Implants: An Histologic Analysis in Monkeys

Abstract: Aim of this study was to evaluate peri-implant tissue reactions to immediately loaded titanium plasma-sprayed implants in Macaca fascicularis monkeys. A total of 48 titanium plasma-sprayed implants were inserted (24 in the posterior maxilla and 24 in the posterior mandible). A metal superstructure was cemented 3 days after implant insertion on 24 implants (12 in the maxilla and 12 in the mandible) (test implants). The remaining 24 implants (12 in the maxilla and 12 in the mandible) were left unloaded (control implants). Nine months after implant placement a block section was carried out, the defect filled with non-resorbable hydroxyapatite, and all 48 implants retrieved. The implants were treated to obtain thin ground sections. Three slides were cut for each implant and examined under normal and polarized light and a morphometrical analysis done. All implants were covered by bone under light microscopy. The histomorphometrical analysis demonstrated that in test implants, the bone-implant contact percentag...

Histological evaluation of Bio-Oss in a 2-stage sinus floor elevation and implantation procedure. A human case report.

Abstract: Deproteinized cancellous bovine bone (Bio-Oss) was placed as a grafting material for sinus floor elevation in the right posterior maxilla. After 6 months of healing, 3 cylindrical titanium-plasma coated implants were inserted. Six months later at the abutment connection, it was realized that 1 of the implants could not be reconstructed due to unfavorable positioning. This implant was removed along with a small portion of the surrounding peri-implant tissues. The specimen was processed according to standard techniques for hard tissue histology. In both the grafted area and the previously existing area of the sinus floor the bone was primarily of lamellar structure. Intimate contact between newly formed bone and the particles of the graft was present. No overt signs of resorption of the graft particles were visible. Histomorphometric analysis revealed 63% of implant-bone contact in the zone of pre-existing bone, and 73% in the grafted zone. The area density of bone amounted to 27% in the non-grafted as compared to 28% in the grafted area. In conclusion, this case report documented that deproteinized bovine bone, when used as a grafting material for augmentation of the sinus floor, may lead to proper osseointegration of a dental implant.

Generalizations regarding the process and phenomenon of osseointegration. Part II. In vitro studies.

Abstract: The clinical success of endosseous implants is associated with the formation and maintenance of bone at implant surfaces. Histologic analyses have indicated that bone formation at a variety of implant surfaces is a continuous process that supports long-term functional integration. Based on in vivo observations, several generalizations have been derived regarding the nature of the interface. Experimental descriptions indicate that the implantbone interface may be characterized in spatial and temporal terms as discontinuous. Biomechanical tests of the bone associations with implants demonstrate that the chemical composition and the surface topography of the implant influence the rate and extent of bone formation at implant surfaces. The precise character and functional attributes of this interface are the focus of this investigation. Many technical difficulties are associated with its structural and chemical characterization in vivo. Despite the technically difficult nature of this type of analysis and the limitations of current histologic examinations and biomechanical tests, in vivo models of osseointegration are necessary experimental tools for the continued empirical development of clinical implant applications.

Implants Placed in Immediate Extraction Sites: A Report of Histologic and Histometric Analyses of Human Biopsies

Abstract: Five titanium plasma-sprayed implants were biopsied from a human volunteer 6 months after placement. Four test implants had been placed in immediate extraction sockets, while one implant was placed in a mature site and served as a control. The histologic analysis demonstrated that all five implants achieved osseointegration as demonstrated by light microscopy, whereas a varying degree of bone-implant contact was observed. The non-loaded control implant had the highest percentage of bone-implant contact, 72%, followed by the two implants placed in the canine sites presenting with a horizontal defect dimension of 1.5 nm or less. These implants were placed without a barrier membrane, but in a submerged fashion. The histometric analysis showed a mean bone-implant contact of 50% for these two implants. The lowest mean bone-implant contact (17%) was observed for the two molar implants, which had horizontal defect dimensions of 4 mm; these implants were placed in a non-submerged fashion with the implants perforating an expanded polytetrafluoroethylene membrane. The authors concluded that osseointegration may occur in immediate extraction sites in humans using titanium implants with a plasma-sprayed surface. The horizontal component of the peri-implant defect was apparently the most critical factor relating to the final amount of bone-implant contact.

Sinus floor elevation using anorganic bovine bone matrix (OsteoGraf/N) with and without autogenous bone: a clinical, histologic, radiographic, and histomorphometric analysis--Part 2 of an ongoing prospective study.

Abstract: One of the goals of the sinus elevation procedure is the creation of vital bone to effect the osseointegration of dental implants placed in the posterior maxilla. With this goal in mind, in 1993 the Department of Implant Dentistry at New York University College of Dentistry began a long-term clinical, histologic, histomorphometric, and radiographic study of the sinus elevation procedure. The primary parameters included the effects of graft material selection, time allowed for graft maturation, and the effect of barrier membrane placement on the creation of vital bone in the sinus cavity. The effects of these and other parameters on implant survival rates were also to be evaluated. This paper reports the data collected on a subgroup of 113 sinus elevations that used anorganic bovine bone matrix (OsteoGraf/N) alone or in combination with autogenous bone and/or demineralized freeze-dried bone as a graft material. This is the second in a proposed series of papers that will result from this ongoing research project. The results of this study indicate that: OsteoGraf/N appears to be an effective graft material with a 98.2% implant survival rate to date: vital bone formation increased with time; vital bone formation increased moderately when demineralized freeze-dried bone allograft was added, and increased substantially when intraoral autogenous bone was added or when an expanded polytetrafluoroethylene membrane was used; and the increased height achieved by the procedure was stable over a 3-year period. Because of the high overall implant survival rate, it was not possible to determine the relationship between vital bone formation or membrane usage and implant survival.

Bovine hydroxyapatite for maxillary sinus grafting: comparative histomorphometric findings in sheep

Abstract: This experimental study in animals examines the value of bovine hydroxyapatite as grafting material in one-stage sinus lift procedure. The Schneiderian membrane was elevated from extraorally in 54 sinuses of 27 adult female mountain sheep. Two titanium plasma-flame-spray coated cylindrical implants were placed in each sinus in the same session. In 2 groups of 18 sinuses each, the subantral hollow space was filled with bovine hydroxyapatite and autogenous cancellous bone from the iliac crest, respectively. Eighteen sinuses that were left empty served as a control group. Polyfluorochrome sequential labelling (tetracycline, calcein green, alizarin complexon) was carried out 4 weeks postoperatively, 2 weeks before the animals were sacrificed, and halfway through the observation period to assess new bone formation. The selected observation periods were 12 weeks, 16 weeks, and 26 weeks. Six sinuses per observation period and test group were available for histologic evaluation. All implants showed favourable osseointegration into local bone. New bone formation was observed in a triangular area bound by the implant surface, the local buccal antral wall, and submucous connective tissue in all implants. Bovine hydroxyapatite adjacent to local bone was mainly surrounded by bone tissue. There was a great variation in the extent of bony sheathing of the hydroxyapatite particles, irrespective of the animals' survival time. Macrophages were found around HA particles that were not surrounded by bone as well as on free implant surfaces. The mean length of the bone-implant bond was 3.86 mm in the group of empty sinuses, 4.87 mm in the group augmented with hydroxyapatite, and 5.66 mm in the group augmented with autogenous cancellous bone. During the observation period, the relative length of bone in direct contact with the implant surface increased from 20.0% to 25.1% in the control group, from 30.4% to 35.5% in the group treated with autogenous cancellous bone, and from 27.4% to 34.7% in the HA group. Autogenous cancellous bone showed a significantly greater bone-implant contact than did the control group (P = 0.0004) and the HA group (P = 0.0499). When the apical implant portions were examined separately, both HA (P = 0.006) and autogenous cancellous bone (P = 0.005) showed a significantly better bone-implant bond than did the control group.

Biomimetic calcium phosphate implant coatings and methods for making the same

Abstract: This invention encompasses porous, nanocrystalline, biomimetic calcium phosphate coatings of the order of 2-30 microns that can be grown on metal implants. The chemical surface treatments and methods for making the calcium phosphate coatings are disclosed. Post treatment with dilute hydrogels such as phema reinforce the inorganic structure and enhance the mechanical strength of the coatings. Methods are also disclosed for adsorbing or covalently attaching growth factor proteins to derivatives of the hydrogel coated calcium phosphate coatings. Such hydrogel reinforced calcium phosphate coatings show equivalent bone tissue growth as the currently used implants and are easily resorbed. This property in combination with the immobilized growth factors is expected to enhance the process of osseointegration of the disclosed coatings.

Comparison between freestanding and tooth-connected partially stabilized zirconia implants after two years' function in monkeys: A clinical and histologic study

Abstract: Statement of problem. Partially stabilized zirconia implants placed by a 1-stage procedure have been previously shown to obtain initial osseointegration under clinically unloaded condition. However, it is unknown whether freestanding and tooth-connected partially stabilized zirconia implants can maintain a long-term direct bone-implant interface. Purpose. This study examined the possibility of the long-term stability of osseointegration around partially stabilized zirconia implants with a 1-stage procedure with different loading designs. Material And Methods. Thirty-two partially stabilized zirconia implants were placed into the mandibles of 8 monkeys. Three months after implant placement, 3 types of superstructure were provided in each animal to obtain different concepts of support as (1) single freestanding implant support, (2) connected freestanding implant support, and (3) a combination of implant and tooth support. At 12 and 24 months after loading, clinical, histologic, and histomorphometric evaluations of peri-implant tissues were performed on 28 implants. Results. No clear difference in clinical features was observed among the different types of support. Direct bone apposition to the implant was generally seen in all groups. Histometrically, bone contact ratio ranged between 66% and 81%, and bone area ratio varied between 49% and 78% at 24 months after loading. These values showed almost no difference among single freestanding, connected freestanding, and implant-tooth supports of partially stabilized zirconia implants. Conclusion. In a primate model, partially stabilized zirconia implants placed with a 1-stage procedure achieve long-term stability of osseointegration with the use of single freestanding, connected freestanding, and implant-tooth supports. (J Prosthet Dent 1998;80:551-8.)

A comparison of maxillary and mandibular bone mineral densities

Abstract: Statement of problem. The success rate of implant osseointegration is dependent on many factors such as bone mineral density, volume and vascularity of bone, implant design, ridge shape, and patient selection criteria among others. Purpose. This study examined whether a technique to measure differences in bone mineral density in the maxilla and mandible might be useful to predict the likelihood of successful osseointegration. Material and methods. Bone densitometry of the jaws was performed with a densitometer, and bone mineral density was calculated at three regions of the maxilla and one site in the mandibular body in 39 edentulous subjects. Results. Significant differences were found between the mean bone mineral density of each site when compared with the three other locations. The mean bone mineral density for the mandible (mean = 1.11 g·cm -2 ), was twice that of the anterior maxilla (mean = 0.55 g·cm -2 ). Both were significantly greater than the bone mineral density of the posterior maxilla (mean = 0.31 g·cm -2 ; including the hard palate, mean=0.45 g·cm -2 ). The bone mineral densities at the three maxillary sites were all highly correlated ( r ≥ 0.78, p Conclusion. The dissimilarity in bone mineral density at different mandibular and maxillary sites may partly explain some variation in previously reported osseointegration rates. The posterior maxilla had the lowest bone mineral density and in certain circumstances before implant insertion, bone augmentation, or guided tissue regeneration may be advisable to improve the rate of osseointegration. Because the radiation dose is low, dual energy x-ray absorptiometry may be a useful noninvasive technique for determining the bone mineral density before implant insertion. (J Prosthet Dent 1998;79:323-7.)

Cemented single crowns on osseointegrated implants after 5 years: results from a prospective study on CeraOne

Abstract: Purpose The aim of this prospective study was to present the results after 5 years of loading of 65 CeraOne (Nobel Biocare) crowns. Materials and methods Sixty-two implants in the maxilla and 3 implants in the mandible were placed in 57 patients. Sixty-two all-ceramic and three metal-ceramic crowns were cemented. The group comprised the first patients treated with the CeraOne prosthodontic concept. Results Eight patients did not complete the study. Only one implant failed, giving a cumulative success rate for implants of 98.5%. The failed implant was replaced: a crown was cemented and then followed for 5 years without any complications. Four crowns were recorded as failures, giving a cumulative success rate for crowns of 93.7%. It should be observed that this result was very positive, as all crown failures were related to extraordinary causes and not one was a result of common bite forces or fatigue. The initial bone loss was in accordance with other studies on Branemark implants, and a stable situation was recorded after 2 years for the supporting bone around implants and adjacent teeth when the conical implants were excluded. Soft tissues around implants and adjacent teeth appeared healthy, and the cementation and the placement of the abutment shoulder in the peri-implant sulcus did not cause any recession of the peri-implant mucosa. Conclusion CeraOne experienced virtually no complications and proved to be a highly predictable and safe prosthodontic concept. CeraOne also eliminated problems with abutment screw loosening and created a platform for good esthetic results and satisfied patients.

Osteotransductive bone cements

Abstract: Calcium phosphate bone cements (CPBCs) are osteotransductive, i.e. after implantation in bone they are transformed into new bone tissue. Furthermore, due to the fact that they are mouldable, their osteointegration is immediate. Their chemistry has been established previously. Some CPBCs contain amorphous calcium phosphate (ACP) and set by a sol-gel transition. The others are crystalline and can give as the reaction product dicalcium phosphate dihydrate (DCPD), calcium-deficient hydroxyapatite (CDHA), carbonated apatite (CA) or hydroxyapatite (HA). Mixed-type gypsum-DCPD cements are also described. In vivo rates of osteotransduction vary as follows: gypsum-DCPD > DCPD > CDHA approximately CA > HA. The osteotransduction of CDHA-type cements may be increased by adding dicalcium phosphate anhydrous (DCP) and/or CaCO3 to the cement powder. CPBCs can be used for healing of bone defects, bone augmentation and bone reconstruction. Incorporation of drugs like antibiotics and bone morphogenetic protein is envisaged. Load-bearing applications are allowed for CHDA-type, CA-type and HA-type CPBCs as they have a higher compressive strength than human trabecular bone (10 MPa).

Resonance frequency analysis: measuring implant stability and osseointegration.

Abstract: Achievement and maintenance of implant stability are prerequisites for long-term positive outcomes for osseointegrated implants. Thus, implant stability is the key to clinical success. Until recently, it was not possible for the clinician to predictably distinguish implants with different degrees of stability. Because there seems to be a correlation between implant failure and bone properties, it is possible that clinically firms implants with poor stability are more prone to failure than more stable implants. This article discusses the development and possible future use of a novel technique for clinical measurement of implant stability and osseointegration--resonance frequency analysis.

Wound healing around endosseous implants in experimental diabetes.

Abstract: Wound healing has been shown to be altered in diabetes mellitus. The aim of this study was to identify the effects of streptozotocin-induced diabetes on osseointegration. Diabetes was induced in 40-day-old rats by intraperitoneal injection of 70 mg per kg streptozotocin. At 14 days postinjection, implants were placed in the femora of 10 diabetic and 10 age-matched normal rats. Animals were sacrificed at 28 and 56 days following implantation. Histometric results indicated that the quantity of bone formation was similar for diabetic and control animals (P > .05). However, less bone-implant contact was observed for diabetic compared to control animals at both 28 and 56 days (P < .0001). This study demonstrates that the process of osseointegration is affected by streptozotocin-induced diabetes.

A 5-year randomized clinical trial on the influence of splinted and unsplinted oral implants in the mandibular overdenture therapy. Part I: Peri-implant outcome.

Abstract: Thirty-six completely edentulous patients were enrolled for a 5-year prospective study testing the treatment outcome between splinted and unsplinted implants retaining a mandibular hinging overdenture. The patients were randomized into 3 groups of equal size depending on the attachment system used such as: magnets, ball attachments or bars (reference group). Only 1 implant out of the 72 had failed at the abutment stage. Not a single implant failed during the 5-year loading period. The accumulation of plaque was significantly higher for the Magnet than for the Ball group. Bleeding on probing, as well as marginal bone level, attachment level and Periotest values did not statistically differ among the groups, neither at year 1 nor at year 5. However, the Periotest values were significantly lower at year 5 compared to year 1 for all groups, which indicates a higher rigidity at the bone-implant interface. No correlation was found between bleeding on probing and marginal bone loss. We conclude that the connection state of 2 implants retaining a hinging overdenture did not influence the peri-implant outcome.

The effects of age, jaw site, and bone condition on oral implant outcomes.

Abstract: PURPOSE: This paper reviews literature on age and jaw site in relation to jawbone quantity and quality and the osseointegration of endosseous oral implants. RESULTS AND DISCUSSION: The condition of jawbone is both age- and site-specific. However, increased age does not appear to affect the clinical potential for osseointegration or the rate of crestal bone resorption observed around oral implants. In contrast, jaw site is related significantly to osseointegration potential; mandibular sites tend to be more successful than maxillary sites. The reason for this may be that jawbone quality and quantity are often more compromised in maxillary than in mandibular sites. However, evaluation of this relationship has been hampered by a lack of evidence to support the validity and reliability of methods used to assess jawbone condition preoperatively. Furthermore, short-term evidence suggests that high rates of implant success can be achieved in maxillary sites, even those with low trabecular density, if an adequate volume of bone exists to accommodate the implants. Although the rate of crestal bone resorption around oral implants is usually low and may not be site-specific, there is some evidence that it may be greater in sites with less preoperative resorption associated with shorter periods of edentulism. This pattern of bone loss could jeopardize long-term implant outcomes especially in younger implant patients. Another concern in young growing patients is that their prosthetic outcome may become compromised because osseointegrated implants cannot keep pace with growth and development in surrounding structures. CONCLUSION: To improve our understanding of how the age- and site-specificity of jawbone condition affects oral implant outcomes, research needs to be aimed at establishing reliable and valid measures of preoperative jawbone condition, and at better documenting the effects of jawbone condition on oral implant outcomes.

Biologic determinants of bone formation for osseointegration: Clues for future clinical improvements

Abstract: Statement of problem. Further improvement in and expansion of the application of dental implants requires control and improvement of bone mass for implant support. Purpose. Although osseointegration involves both the formation and the maintenance of bone at implant surfaces, the aim of this article is to identify cellular and molecular determinants of bone formation that may be used in clinical attempts to enhance or expand the application of endosseous implants for dental and craniofacial prosthetics. Methods. A review of bone biology and dental and orthopedic implant literature was performed using Medline and published monographs. Results. This spectrum of information indicates that molecular and cellular approaches to creating and maintaining bone mass may be used to expand the application of dental implants and to improve dental implant success in bone-deficient sites. (J Prosthet Dent 1998;80:439-49.)