Showing papers in "International Journal of Oral & Maxillofacial Implants in 2003"

Is platelet-rich plasma the perfect enhancement factor? A current review.

Abstract: Guided bone regeneration is an accepted surgical method employed in implant dentistry to increase the quantity and quality of the host bone in areas of localized alveolar defects. The lack of predictability in osseous regenerative procedures with various grafting materials suggests that improvement in the osteoinductive properties of these materials is highly desirable. Platelet-rich plasma (PRP), a modification of fibrin glue made from autologous blood, is being used to deliver growth factors in high concentration to sites requiring osseous grafting. Growth factors released from the platelets include platelet-derived growth factor, transforming growth factor beta, platelet-derived epidermal growth factor, platelet-derived angiogenesis factor, insulin-like growth factor 1, and platelet factor 4. These factors signal the local mesenchymal and epithelial cells to migrate, divide, and increase collagen and matrix synthesis. PRP has been suggested for use to increase the rate of bone deposition and quality of bone regeneration when augmenting sites prior to or in conjunction with dental implant placement Only 6 human studies using PRP have been found in the dental implant literature and 5 were case series or reports. Thus, there is clearly a lack of scientific evidence to support the use of PRP in combination with bone grafts during augmentation procedures. This novel and potentially promising technique requires well-designed, controlled studies to provide evidence of efficacy.

Immediate placement and provisionalization of maxillary anterior single implants: 1-year prospective study.

Abstract: Purpose This 1-year prospective study evaluated the implant success rate, peri-implant tissue response, and esthetic outcome of immediately placed and provisionalized maxillary anterior single implants. Materials and methods Thirty-five patients (8 men, 27 women) with a mean age of 36.5 years (range 18 to 65) were included in this study. Thirty-five threaded, hydroxyapatite-coated implants were placed and provisionalized immediately after each failing tooth had been removed. The definitive restoration was placed 6 months later. The patients were evaluated clinically and radiographically at implant placement and at 3, 6, and 12 months after implant placement. Results At 12 months, all implants remained osseointegrated. The mean marginal bone change from the time of implant placement to 12 months was -0.26 +/- 0.40 mm mesially and -0.22 +/- 0.28 mm distally. No significant differences in the Plaque Index scores were noted at different time intervals. The mean midfacial gingival level and mesial and distal papilla level changes from pretreatment to 12 months were -0.55 +/- 0.53 mm, -0.53 +/- 0.39 mm, and -0.39 +/- 0.40 mm, respectively. All patients were very satisfied with the esthetic outcome and none had noticed any changes at the gingival level. Discussion Although marginal bone and gingival level changes were statistically significant from pretreatment to 12 months of follow-up, they were well within clinical expectations. Conclusion The results of this study suggest that favorable implant success rates, peri-implant tissue responses, and esthetic outcomes can be achieved with immediately placed and provisionalized maxillary anterior single implants.

Accuracy of Implant Placement with a Stereolithographic Surgical Guide

Abstract: Purpose: Placement of dental implants requires precise planning that accounts for anatomic limitations and restorative goals. Diagnosis can be made with the assistance of computerized tomographic (CT) scanning, but transfer of planning to the surgical field is limited. Recently, novel CAD/CAM techniques such as stereolithographic rapid prototyping have been developed to build surgical guides in an attempt to improve precision of implant placement. However, comparison of these advanced techniques to traditional surgical guides has not been performed. The goal of this study was to compare the accuracy of a conventional surgical guide to that of a stereolithographic surgical guide. Materials and Methods: CT scanning of epoxy edentulous mandibles was performed using a cone beam CT scanner with high isotropic spatial resolution, while planning for 5 implants on each side of the jaw was performed using a commercially available software package. Five surgeons performed osteotomies on a jaw identical to the initial model; on the right side a conventional surgical guide (control side) was used, and on the left side a stereolithographic guide was used (test side). Each jaw was then CT scanned, and a registration method was applied to match it to the initial planning. Measurements included distances between planned implants and actual osteotomies. Results: The average distance between the planned implant and the actual osteotomy was 1.5 mm at the entrance and 2.1 mm at the apex when the control guide was used. The same measurements were significantly reduced to 0.9 mm and 1.0 mm when the test guide was used. Variations were also reduced with the test guide, within surgeons and between surgeons. Discussion: Surgical guidance for implant placement relieves the clinician from multiple perioperative decisions. Precise implant placement is under investigation using sophisticated guidance methods, including CAD/CAM templates. Conclusion: Within the limits of this study, implant placement was improved by using a stereolithographic surgical guide. (INT J ORAL MAXILLOFAC IMPLANTS 2003;18:571‐577)

Influence of implant design and bone quality on stress/strain distribution in bone around implants: a 3-dimensional finite element analysis.

Abstract: Purpose A 3-dimensional finite element analysis was performed to evaluate the influence of implant type and length, as well as that of bone quality, on the stress/strain in bone and implant. Materials and methods Two types (screw and cylinder) and 4 lengths (9.2, 10.8, 12.4, and 14.0 mm) of titanium implants were buried in 4 types of bone modeled by varying the elastic modulus for cancellous bone. Axial and buccolingual forces were applied to the occlusal node at the center of the abutment. Results Regardless of load direction, maximum equivalent stress/strain in bone increased with a decrease in cancellous bone density. Under axial load, especially in the low-density bone models, maximum equivalent strain in cancellous bone was lower with the screw-type implant than with the cylinder-type implant. It was also lower with the longer implants than with the shorter implants. Under buccolingual load, equivalent stress/strain was influenced mainly by bone density. Discussion This study confirms the importance of bone quality and its presurgical diagnosis for implant long-term prognosis. Implant length and type can also influence bone strain, especially in low-density bone. Conclusions The results of this study suggest that cancellous bone of higher rather than lower density might ensure a better biomechanical environment for implants. Moreover, longer screw-type implants could be a better choice in a jaw with cancellous bone of low density.

Cement-retained versus screw-retained implant restorations: a critical review

Abstract: This article presents a comparison of screw-retained and cement-retained implant prostheses based on the literature. The advantages, disadvantages, and limitations of the 2 different types of restorations are discussed, because it is important to understand the influence of the attachment mechanism on many clinical aspects of implant dentistry. Several factors essential to the long-term success of any implant prosthesis were reviewed with regard to both methods of fixation. These factors include: (1) ease of fabrication and cost, (2) passivity of the framework, (3) retention, (4) occlusion, (5) esthetics, (6) delivery, and (7) retrievability. (More than 50 references).

Bone healing following immediate versus delayed placement of titanium implants into extraction sockets: a prospective clinical study.

Abstract: Purpose The aim of this study was to compare bone healing and crestal bone changes following immediate (Im) versus delayed (De) placement of titanium dental implants with acid-etched surfaces (Osseotite) in extraction sockets. Materials and methods Forty-six patients were randomly allocated to the Im or De group (n = 23 per group) and received 1 implant at the incisor, canine, or premolar region of the maxilla or the mandible. The implants were placed an average of 10 days following tooth extraction in the Im group and approximately 3 months after extraction in the De group. The widths (parallel and perpendicular to the implant) and the depth of marginal bone defects around the implants were measured clinically just after placement and 3 months later at the abutment surgery. The crestal bone changes mesially and distally to the implants were evaluated radiographically by linear measurements. Results The survival rates were 91% in the Im group and 96% in the De group. In the Im group, the mean reductions in parallel width, perpendicular width, and depth of the largest defect of each implant amounted to 48% (from 4.4 to 2.3 mm), 59% (from 2.2 to 0.9 mm), and 48% (from 6.9 to 3.6 mm), respectively. The corresponding mean reductions in the De group amounted to 39% (from 3.1 to 1.9 mm), 77% (from 1.3 to 0.3 mm), and 34% (from 4.4 to 2.9 mm). The reduction over time was statistically significant in both groups (P 60% for depth) than in dehiscence-type defects (approximately 25%). Furthermore, 70% of the 3-wall infrabony defects with a parallel width of up to 5 mm, a depth of maximum 4 mm, and a perpendicular width of maximum 2 mm had a capacity of spontaneous healing within a period of 3 months. Discussion and conclusion New bone formation occurs in infrabony defects associated with immediately placed implants in extraction sockets.

Resonance frequency measurement of implant stability in vivo on implants with a sandblasted and acid-etched surface.

Abstract: Purpose To determine the changes in stability as a reflection of early healing around single-stage, roughened-surface implants in humans utilizing resonance frequency analysis (RFA). RFA makes use of a transducer, attached to an implant, which is excited over a range of sound frequencies with subsequent response analysis. Materials and methods Twenty patients had 1 to 4 implants placed in the posterior maxilla or mandible. Bone type was classified into 1 of 4 groups according to the Lekholm and Zarb index (1985). RFA was used for direct measurement of implant stability on the day of implant placement and consecutively once per week for 6 weeks and at weeks 8 and 10. Results Twenty-seven ITI SLA implants placed in the premolar and molar regions of the maxilla and mandible were evaluated. Early failure occurred with 1 implant related to parafunction. The remaining 26 implants were distributed as follows: 29.6% in Type 1 bone, 37% in Type 2 or 3 bone, and 33.3% in Type 4 bone. The lowest mean stability measurement was at 3 weeks for all bone types. The percentage decrease in stability from baseline to 3 weeks was highest for Type 4 bone (8.6%), as was the percentage increase in stability from 3 to 10 weeks (26.9%). A Bonferroni adjusted Student t test comparison of bone groups at each time point revealed highly significant differences between implant stability in Types 1 and 4 bone at 3 weeks (P = .004) and a moderately significant difference between Types 2, 3, and 4 bone (P = .08) at 3 weeks. Implant stability did not change significantly during the 10-week period in Type 1 bone (P > .10). With the same test, by 5 weeks, no bone groups showed any difference in implant RFA measurements (P = 1.0). Discussion This study demonstrated the lowest values for implant stability at 3 weeks after placement for all bone types. This effect was statistically significant and most pronounced in Type 4 bone. Conclusion There was no significant difference in the pattern of stability changes among different bone types after 5 weeks of healing.

Histologic findings in sinus augmentation with autogenous bone chips versus a bovine bone substitute.

Abstract: Purpose The aim of this study was to compare a bovine bone substitute (Bio-Oss) to autogenous bone with respect to its value as a material for sinus augmentation. Materials and methods In 10 beagle dogs 12 months of age, the 3 maxillary premolars were extracted on both sides. Six weeks later, 2 cavities of predefined size were produced in the region of the nasal cavity. The antral window was 25 mm long and had a vertical extension of 7 mm. Two Frialit-2 implants (3 x 8 mm) were placed in each bone defect (n = 20). Every implant was primarily stable because of fixation in native bone. In each maxilla, 1 bone defect was filled with autogenous bone harvested from the mandible and 1 was filled with Bio-Oss (material selected at random). The animals were sacrificed at 90 and 180 days, and histologic specimens were examined and the results subjected to statistical analysis by the Wilcoxon test for paired observations. Results No healing problems were observed. Histologically, after 90 days the volume of the augmentation showed a reduction of 14.6 +/- 4.4% within the Bio-Oss group and 3.8 +/- 2.5% in the group with autogenous bone. Bone-implant contact of 52.16 +/- 13.15% in the Bio-Oss group and 60.21 +/- 11.46% in the autogenous bone group was observed. At 180 days, the Bio-Oss group showed bony ingrowth of the substitute, whereas in the autogenous group a differentiation from original bone could no longer be made. The volume reduction was 16.5 +/- 8.67% in the Bio-Oss group and 39.8 +/- 16.14% in the autogenous group. Bone-implant contact of 63.43 +/- 19.56% in the Bio-Oss group and 42.22 +/- 12.80% in the autogenous bone group was measured. Discussion and conclusion The results indicated that because of the nonresorptive properties of the bone substitute Bio-Oss, regeneration of the defects is achievable. It was demonstrated that the bone substitute seemed to behave as a permanent implant. The volume of the area augmented by autogenous bone decreased over the observation period.

Different bone integration profiles of turned and acid-etched implants associated with modulated expression of extracellular matrix genes.

Abstract: Purpose The manner in which surface roughness of Implants affects bone-implant integration remains unknown. This study correlated morphologic profiles of bone-implant integration and extracellular matrix (ECM) gene expression in response to the placement of implants with different surface topographies. Materials and methods T-shaped hollow implants with turned and dual acid-etched (DE) surfaces were placed into rat femurs. A bone integration curve (BIC) was created from serial histomorphometric measurements within the implant chamber. The mRNA expression pattern of ECM genes in bone healing with or without implants was examined using reverse transcriptase-polymerase chain reaction. Results At week 2, the BIC of the DE implant increased near the implant surface, whereas that of the turned implant decreased. The bone-to-implant contact rate of the DE Implant was 6- and 2.5-fold higher than that of the tuned Implant at weeks 2 and 4, respectively. A spatially standardized histomorphometry revealed that, at week 2, the DE implant had a greater bone volume than the turned implant in a zone near the implant, but not in zones distant from the implant surface. The DE implant evoked an accelerated mRNA expression for osteonectin and osteocalcin compared with the turned Implant, along with an up-regulated expression for bone sialoprotein II, collagen III, and integrins in initial healing stages up to week 1. Discussion and conclusion The results indicate that different histologic bone integration profiles associated with increased surface roughness may be explained, in part, by the modulated expression of the selected ECM-related genes. The data provide evidence supporting the fact that gene regulation occurs at local levels of implant surfaces in vivo.

Maxillary sinus grafting with anorganic bovine bone: a clinical report of long-term results.

Abstract: Purpose The aim of the present retrospective study was to evaluate the survival rate of titanium plasma spray-coated cylindric and machined screw-type implants placed in sinuses grafted with anorganic bovine bone mixed with demineralized freeze-dried bone allograft (DFDBA) or with anorganic bovine bone alone. Materials and methods The patients included in this study were treated with a 1- or 2-stage technique, according to the volume of residual bone. This determined the possibility of primary stabilization and the duration of the treatment, which was 9 or 12 months, respectively. Results The overall implant survival rate was 94.5% after a mean functioning period of 6.5 +/- 1.9 years. The Implant survival rate was better in sinuses grafted with anorganic bovine bone alone than with a mixture of anorganic bovine bone with DFDBA (96.8% versus 90%). The implant survival rate was similar for cylindric and screw-type implants in sinuses grafted with anorganic bovine bone alone. Discussion Because of the good bone quality, the implant survival rate was similar for cylindric and screw-type implants in sinuses grafted with anorganic bovine bone. Conclusion Anorganic bovine bone used alone appears to be a suitable material for sinus floor augmentation.

Histologic evaluation of bone response to oxidized and turned titanium micro-implants in human jawbone.

Abstract: PURPOSE: To evaluate the human bone tissue response to 2 surfaces (oxidized or turned) on commercially available titanium implants. MATERIALS AND METHODS: Screw-type turned (control) and oxidized ( ...

Influence of platelet-rich plasma on osseous healing of dental implants : A histologic and histomorphometric study in minipigs

Abstract: Purpose In the present study the time course of local bone formation following the application of PRP during implant placement was evaluated histomorphometrically and histologically. Materials and methods The mandibular premolars of 12 adult minipigs were removed surgically and 72 sites were prepared for implant placement. Before the implants (MK III, Replace, and MK III TiUnite) were placed, autogenous PRP (8 x 10(5) to 10 x 10(5) platelets/microL) was instilled into the host sites on the left side. The animals were sacrificed at 3, 6, and 12 weeks, and undecalcified ground sections were prepared. Results The histomorphometric evaluation showed significantly more bone-to-implant contact after topical PRP application in the early healing phase (6 weeks), which varied as a function of the distance from the implant surface (controls = 24.2% versus PRP = 44.21%; P = .013). At 12 weeks, the extent of osteoneogenesis was comparable in the 2 groups (controls = 51.3% versus PRP = 44.2%; P = .251). Statistical analysis revealed no significant interaction between implant surface type and PRP. Discussion Topical PRP application significantly increased the activity of bone regeneration at implant host sites during early healing. Conclusion In the present study PRP was found to have a time- and site-dependent effect on peri-implant bone healing.

Comparison of implant-retained mandibular overdentures and conventional complete dentures: a 10-year prospective study of clinical aspects and patient satisfaction.

Abstract: Purpose: The aim of this prospective randomized clinical trial was to evaluate 10 years of treatment of patients receiving a mandibular implant-retained overdenture (IRO) or a conventional complete denture (CD). Materials and Methods: One hundred twenty-one edentulous patients were treated with an IRO (2 endosseous implants, n = 61) or a conventional CD (n = 60). Clinical aspects and patient satisfaction were evaluated. One year after placement of the denture, unsatisfied patients of the CD group were given the opportunity to receive implants. Results: In the IRO group, 4 implants were lost during the first year and 4 implants were lost during the next 4 years. Between 5 and 10 years, no implants were lost (survival rate: 93%). In the CD group, 24 patients (40%) chose an IRO between 1 and 10 years. Discussion: Patients in the IRO group were significantly more satisfied than patients in the CD group after 1 year (satisfaction score 8.3 versus 6.6 on a scale of 1 to 10), after 5 years (7.4 versus 6.4), and after 10 years (7.7 versus 6.8). Conclusion: The mean satisfaction score of the CD group (including patients who later received implants) was still lower than that of the IRO group, in spite of the opportunity for retreatment with IROs. Endosseous implants had a high survival rate after 10 years of follow-up.

A prospective multicenter clinical trial of 3i machined-surface implants: results after 6 years of follow-up.

Abstract: PURPOSE In this prospective multicenter clinical study, 1,179 3i standard threaded and self-tapping implants were followed for up to 6 years and monitored according to established success criteria. MATERIALS AND METHODS A total of 493 patients (240 men and 253 women) with a mean age of 45.1 years at implant surgery were enrolled at 6 research centers after being screened for exclusion criteria. Implants were placed according to a 2-stage surgical protocol with a minimum of 4 months of submerged healing in the mandible and 6 months in the maxilla. Restorations included 633 prostheses, the majority of which were fixed partial dentures in the posterior mandible or maxilla or single-tooth replacements in the anterior maxilla. RESULTS One hundred four implants (8.8%) did not meet success criteria and were designated as failures, and 222 implants (18.8%) were lost to follow-up. The cumulative success rate according to life table methods was 91.1% at 6 years. DISCUSSION Sixty percent of the failed implants were short (< or = 10 mm long), and their cumulative success rate as a group at 6 years was 89.0%, compared to 93.1% for longer implants (P < .05). Thirty-three percent of all failures were implants placed in the posterior maxilla, for a 5-year cumulative success rate of 87.4%. CONCLUSION It appears that limited bone dimensions and poor-quality bone have an impact on the performance of these machined-surface implants.

Complications of dental implants: identification, frequency, and associated risk factors.

Abstract: PURPOSE This study sought to identify the types, frequencies, and risk factors associated with complications following placement of dental implants. It was hypothesized that one or more factors could be identified that are associated with an increased risk for complications and may be modified by the clinician to enhance outcome. MATERIALS AND METHODS A retrospective cohort study design was used that included patients who received Bicon implants (Bicon, Boston, MA) between 1992 and 2000. Predictor variables were grouped into demographic, medical history, implant-specific, anatomic, prosthetic, and reconstructive categories. Complications were grouped into inflammatory, prosthetic, operative, and major or minor categories. Cox proportional hazards regression models were developed to identify risk factors for complications. RESULTS The sample was composed of 677 patients. The overall frequency of implant complications was 13.9% (10.2% inflammatory, 2.7% prosthetic, 1.0% operative), of which 53% were minor. The multivariate Cox model revealed that smoking, use of 1-stage implants, and reconstructive procedures were statistically associated with an increased risk for overall complications (P < or = .05). The median duration of follow-up was 13.1 months (range 0 to 85.6 months). DISCUSSION A lower frequency of complications was found compared to mean frequencies calculated from past reports. Investigations examining the influence of smoking and reconstructive procedures on implant complications are recommended. CONCLUSION Of the 3 factors associated with an increased risk for complications, tobacco use and implant staging may be modified by the clinician to enhance outcome.

Surface chemistry effects of topographic modification of titanium dental implant surfaces: 1. Surface analysis.

Abstract: Purpose To analyze the surface composition of 34 different commercially available titanium dental implants. Materials and methods Surface composition was evaluated by x-ray photoelectron spectroscopy (XPS). Samples were divided into 4 groups, depending on their surface topography (machined, sandblasted, acid etched, or plasma sprayed). Results Statistical analysis of the data showed a clear relationship between surface composition and topography, which can be easily accounted for by the chemical effects of the surface treatment performed. On average, acid-etched and plasma-sprayed surfaces had higher titanium and lower carbon concentration than machined surfaces. Discussion and conclusion Current studies aimed at the evaluation of implants with different topography should not implicitly assume that topography is the only variable controlling the biologic response. Rather, when comparing different topographies, it should be taken into account that surface chemistry may be a variable as well.

Clinical evaluation of short, machined-surface implants followed for 12 to 92 months.

Abstract: Purpose Bone resorption following tooth loss often limits the quantity of bone available for implant placement The purpose of the present study was to evaluate the clinical outcome of 10-mm or shorter machined-surface implants when used exclusively in the treatment of various forms of edentulism Materials and methods Two hundred sixty-nine screw-type Branemark System implants (Nobel Biocare), 10 mm or shorter, were placed in 111 consecutively treated patients Of the total, 888% were placed in the mandible and 112% were placed in the maxilla; 952% were used to treat partially edentulous situations, including single-tooth losses, of which 966% were in the premolar and molar regions The patients were followed for periods of 12 to 92 months Results Of the 269 placed implants, 12 were lost The overall survival rate was 955% Bone quality 2 and 3 (Lekholm-Zarb classification of 1985) was found in 888% of the treated sites There was no statistical difference in the survival rate of the 10-mm implants when compared to the shorter series (P > 05) or between the various implant diameters The mean marginal bone loss was 071 +/- 065 mm Discussion The failure rate of 45% compares favorably with that of implants of different shape, surface characteristics, and length Bone quality appeared to be the critical factor in implant survival, rather than bone quantity, in this patient series Conclusions This study supports the survival of short, machined-surface implants when used for the treatment of partial edentulism in bone of good quality

Immediate functional loading of Brånemark system implants in edentulous mandibles: clinical report of the results of developmental and simplified protocols.

Abstract: Purpose This report evaluates the 5-year results of 9 of 10 patients in a clinical investigation of immediate functional loading of Branemark System implants in edentulous mandibles, and of 24 patients treated with a simplified protocol for the same indication The purpose of the paper is to suggest a simple, reliable, and documented method for immediate implant loading of complete-arch mandibular prostheses Materials and methods Ten healthy patients in need of full-arch mandibular implant reconstruction (development group) were treated between December 1993 and December 1994 with 130 Branemark System standard Implants, placed in fresh extraction and healed sites Four implants per patient were immediately loaded with acrylic resin fixed prostheses The prostheses were replaced by metal-framework conversion prostheses approximately 6 weeks later, and definitive metal-reinforced prostheses incorporating all implants were placed after second-stage surgery An additional 24 patients were treated with a simplified protocol using a total of 144 implants placed between March 1997 and October 2000 In these patients, the acrylic resin prostheses were not disturbed for 3 months, and fewer implants were used with an increasing ratio of implants loaded Eventually, all Implants were loaded immediately for the last patients treated Results The prosthesis survival rate was 100% for the total material In the developmental group, the implant cumulative survival rate was 80% for the immediately loaded implants after 5 years, while the 2-stage implants reached 96% Bone level measurements showed no differences between immediate and 2-stage protocols for this group The implant cumulative survival rate was 97% for the simplified treatment group Discussion and conclusion A predictable and simple concept for loading of immediate implant prostheses in edentulous mandibles was demonstrated Results from the development of this technique suggest that it may be essential to maintain the initial implant splinting over a healing period of about 3 months and that implant placement between the mental foramina provides optimal support

Posterior mandibular residual ridge resorption in patients with conventional dentures and implant overdentures.

Abstract: Purpose: This study investigated the effects of certain systemic and local factors on resorption of the posterior mandibular residual ridge under conventional dentures and overdentures supported by 2 implants. Materials and Methods: Proportional area measurements of the posterior mandible were made on rotational tomograms taken immediately before and 5 years after treatment. The area was bounded by a line joining gonion to the lowest point of the mental foramen and the crest of the residual ridge and was expressed as a proportion of an area that was not dependent on the ridge. The use of proportions rather than actual measurements minimized errors related to magnification and distortion. Results: The estimated average reduction in height was 1.25 mm in 5 years (1.63 mm for conventional denture groups and 0.69 mm for implant overdenture groups, ie, almost 1 mm less in the overdenture group). Discussion and Conclusion: Female gender was a risk factor for greater resorption. Other factors, such as the number of years a patient had been edentulous, initial height of the mandible, and the number of dentures used, failed to show an association with resorption of the residual posterior mandibular ridge, while the statistically significant effect of age was unlikely to be clinically significant.

Computer-assisted implant placement. A case report: treatment of the mandible.

Abstract: The authors present a case of immediate loading of mandibular implants using a 5-step procedure. The first step consists of building a scannographic template, the second step consists of taking a computerized tomographic (CT) scan, and the third step consists of implant planning using SurgiCase software. The final 2 steps consist of implant placement using a drill guide created by stereolithography and placement of the prosthesis. Using a CT scan-based planning system, the surgeon is able to select the optimal locations for implant placement. By incorporating the prosthetic planning using a scannographic template, the treatment is optimized from a prosthetic point of view. Furthermore, the use of a stereolithographic drill guide allows a physical transfer of the implant planning to the patient's mouth. The scannographic template is designed so that it can be transformed into a temporary fixed prosthesis for immediate loading, and the definitive restoration is placed 3 months later.

Vertical ridge augmentation using xenogenic material supported by a configured titanium mesh: clinicohistopathologic and histochemical study.

Abstract: PURPOSE The aim of this study was to evaluate the capability of a configured titanium mesh (CTM) to serve as a mechanical and biologic device for restoring a vertically defected/resorbed alveolar ridge. MATERIALS AND METHODS The study comprised 10 severely resorbed sites in 10 patients. Pre- and post-operative ridge measurements were taken with reference to the neighboring teeth and supporting screw head base of the CTM. Bovine bone mineral served as the augmentation filler material. The metal mesh was removed after 9 months. Subsequently, root-form, screw-type implants were placed. During the implant placement phase, cylindric bone samples were retrieved from the augmented area for histopathologic and histochemical examination. RESULTS Upon soft tissue reflection and before augmentation, defect height, as recorded by a periodontal probe along the main threads exposed on the support screw, was between 5 and 8 mm (average 6.4 mm; SD +/- 1.17). At 9 months after augmentation, during the implant placement phase, the defect height was between 0 and 2 mm (average 1.2 mm; SD +/- 0.63). Differences were statistically significant (P < .001). Bone height gain was between 4 and 6 mm (average 5.2 mm, SD +/- 0.79), which gave an average bone fill of 81.2% (SD +/- 7.98). Polarizing microscopic examination of sections stained with Picrosirius red showed a gradual increase in new lamellar bone from coronal to apical cuts, reaching the highest area percentage in the deep apical zone. DISCUSSION At 9 months postaugmentation using the CTM surgical technique, the quality and quantity of the newly established hard tissue appeared to be different in the coronal versus apical areas of the restored alveolar ridge. CONCLUSION Although at 9 months postoperatively, the augmented alveolar ridge had different bone content, clinicohistochemical results demonstrated that this surgical technique could be a successful and predictable procedure for rebuilding a resorbed/defected ridge to accommodate endosseous implants.

Immediate occlusal loading of Osseotite implants in the completely edentulous mandible.

Abstract: Purpose This article reports the preliminary data from a clinical study of immediately loaded, full-arch, screw-retained prosthesis with distal extensions (hybrid prosthesis) supported by Osseotite implants placed in the edentulous mandible. Materials and methods Fifteen patients who received 103 implants were enrolled in this study. The first 2 patients received both immediately loaded and submerged implants, while the remaining patients had all implants immediately loaded. The first 9 patients received a temporary prosthesis within 4 hours of surgery, and the hybrid prosthesis, made of a titanium framework and acrylic resin teeth, was placed after 6 months. The last 6 patients received the same type of hybrid prosthesis within 36 hours of surgery. Marginal bone loss was monitored via periapical radiographs by a computerized technique. Results One failure (out of the 92 immediately loaded implants) occurred after 3 weeks of function because of infection. A cumulative success rate of 98.9% was achieved for up to 48 months of follow-up, while the prosthetic cumulative success rate for the same period was 100%. Marginal bone loss at the immediately loaded implants was within the generally accepted conventional limits for standard delayed loading protocols. Discussion This technique can reduce treatment time but should be applied with caution. Conclusion The preliminary results of this study suggest that rehabilitation of the edentulous mandible by an immediately loaded hybrid prosthesis supported by 5 to 6 implants may represent a viable alternative treatment to the classical delayed loading protocols.

Bone density assessments of dental implant sites: 1. Quantitative computed tomography.

Abstract: Purpose: This study was designed to evaluate variations of bone density in designated implant sites using quantitative computed tomography (QCT) and to compare the QCT measurements to subjective evaluation of bone density. Materials and Methods: Sixty-two designated implant sites in jaws of 9 human cadavers were used. Indicator rods, 2 mm in diameter, were placed in all sites. CT images representing 1-mm buccolingual slices immediately mesial and distal to the rods were selected. Bone density (in Hounsfield units) was assessed in a standardized implant area superimposed on the images and was also subjectively evaluated by 2 independent examiners using the Lekholm and Zarb classification. Results: QCT results demonstrated that bone densities may vary markedly when different areas of a designated implant site are compared. The Lekholm and Zarb ratings for the 2 examiners showed coefficients of correlation ranging between 0.5 to 0.7 for the relationships with the QCT values. Within each of the scores used for the subjective classification, however, a wide range of QCT values was observed. Discussion: The results emphasize the importance of the use of radiographic methods prior to implant placement that allow topographically precise assessments of bone density in the region of interest. Conclusion: Access to QCT values should constitute a valuable supplement to subjective bone density evaluations prior to implant placement. (INT J ORAL MAXILLOFAC IMPLANTS 2003;18:224‐231)

Reliability of preoperative planning of an image-guided system for oral implant placement based on 3-dimensional images: an in vivo study.

Abstract: Purpose: The purpose of this study was to assess the reliability of the planning software of an imageguided implant placement system based on a mechanical device coupled with a template stabilized on soft tissue during surgery. Materials and Methods: Thirty consecutive partially or completely edentulous patients were treated with the image-guided system. For each patient, a study prosthesis was fabricated and duplicated in acrylic resin and served as a scanning template. Axial images were obtained from a computerized tomographic scan and transferred to planning software that provides real 3dimensional information to plan implant position. Once the final position of the implant was defined, preoperative data such as the size of implants and anatomic complications were recorded using the planning software. The scanning template was then drilled in that exact position by a drilling machine. During surgery, the drilled template was used as a drill guide. After implant placement, intraoperative data were recorded and statistically compared with the preoperative data using the Kendall correlation coefficient for qualitative data and the Kappa concordance coefficient for quantitative data. Results: Agreement between the preoperative and intraoperative data was high for both implant size and anatomic complications. The Kendall correlation coefficient was 0.8 for the diameter and 0.82 for the length. The Kappa concordance coefficient was 0.87 for both dehiscence and bone graft, 0.88 for osteotomy, and 1.0 for fenestration. Discussion: In the few instances where planning was not perfect, implant placement was completed in a clinically acceptable manner. Conclusion: The results suggest that the image-guided system presented is reliable for the preoperative assessment of implant size and anatomic complications. It may also be reliable for flapless surgery. INT J ORAL MAXILLOFAC IMPLANTS 2003;18:886‐893

Restoration of partially edentulous patients using dental implants with a microtextured surface: a prospective comparison of delayed and immediate full occlusal loading.

Abstract: Purpose The aim of this study was to determine the clinical effectiveness of placing dental implants with microtextured surfaces into full occlusal loading at the time of placement in partially edentulous patients. Materials and methods Two demographically similar groups of 14 patients each were treated with a total of 92 Spline Twist Implants (Centerpulse Dental, Carlsbad, CA). Test implants were placed into immediate full occlusal loading, and control implants were restored using a conventional delayed loading procedure. Otherwise, both groups of patients received similar therapy from the same treatment team. Radiographs, periodontal indices, and Periotest values were recorded every 6 months during routine clinical follow-up appointments. The mean loading time for all prostheses was 24 months at the time of this report. Results No implants failed in the test group, and 1 implant failed before loading in the control group. Cumulative implant success was 98.9% for all implants placed (test group = 100%; control group = 92.9%). Periodontal measurements indicated no significant clinical differences between implants placed into immediate full occlusal loading and those loaded via a conventional delayed protocol. Discussion Immediate full occlusal loading of partial prostheses supported by microtextured implants in partially edentulous patients demonstrated excellent clinical results, with no adverse periodontal effects after 24 months of function. Additional follow-up will provide invaluable information on the long-term effects of this technique. Conclusion Immediate full occlusal loading of partial prostheses supported by microtextured implants can be successfully achieved for 24 months in highly motivated patients with excellent oral hygiene.

Long-term evaluation of submerged and nonsubmerged ITI solid-screw titanium implants: a 10-year life table analysis of 468 implants.

Abstract: Purpose Submerged and nonsubmerged ITI solid-screw titanium implants were followed retrospectively from 1989 to 1993 and prospectively from 1994 on to analyze long-term prognosis in partially and fully edentulous patients. Material and methods A total of 468 implants were consecutively inserted in 191 patients from 1989 to 1998. Two hundred twenty-eight successfully integrated fixed-restoration implants and 238 with removable restorations were restored following a healing period of 4 to 6 months (9 months in sinus floor elevation sites). From 1994 on all implants inserted were documented annually up to 9 years. During examination the clinical status of the implants was analyzed and evaluated according to predefined criteria of success and this allowed the calculation of 10-year cumulative survival and success rates for 468 implants. Results Two implants (0.43%) did not successfully integrate during the healing period, and 8 implants (1.7%) were classified as failures during follow-up (1 late failure under load, 7 with a progressive bone loss from 1 to 3 threads). Including 68 implants in subjects who dropped out (with a dropout rate of 14.4%), the 10-year cumulative survival and success rates were 99.2% and 96.4%, respectively. Discussion Over the course of this long-term study, osseointegrated implants, once used as a last possible solution, became nearly standard in cases of single-tooth implants because of the high rate of long-term success. Life table analysis not only determines whether an implant is functioning, it also makes a statement about its clinical status according to strict success criteria. Conclusion The study demonstrated that ITI solid-screw titanium implants achieved success rates above 95% in a clinical center for an observation period of up to 10 years.

Microbiologic and radiographic analysis of ligature-induced peri-implantitis with different dental implant surfaces.

Abstract: PURPOSE The goal of this study was to evaluate microbiota and radiographic peri-implant bone loss associated with ligature-induced peri-implantitis. MATERIALS AND METHODS Thirty-six dental implants with 4 different surfaces (9 commercially pure titanium, 9 titanium plasma-sprayed, 9 hydroxyapatite, and 9 acid-etched) were placed in the edentulous mandibles of 6 dogs. After 3 months with optimal plaque control, abutment connection was performed. On days 0, 20, 40, and 60 after placement of cotton ligatures, both microbiologic samples and periapical radiographs were obtained. The presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Campylobacter spp, Capnocytophaga spp, Fusobacterium spp, beta-hemolytic Streptococcus, and Candida spp were evaluated culturally. RESULTS P intermedia/nigrescens was detected in 13.89% of implants at baseline and 100% of implants at other periods. P gingivalis was not detected at baseline, but after 20 and 40 days it was detected in 33.34% of implants and at 60 days it was detected in 29.03% of dental implants. Fusobacterium spp was detected in all periods. Streptococci were detected in 16.67% of implants at baseline and in 83.34%, 72.22%, and 77.42% of implants at 20, 40, and 60 days, respectively. Campylobacter spp and Candida spp were detected in low proportions. The total viable count analysis showed no significant differences among surfaces (P = .831), although a significant difference was observed after ligature placement (P < .0014). However, there was no significant qualitative difference, in spite of the difference among the periods. The peri-implant bone loss was not significantly different between all the dental implant surfaces (P = .908). DISCUSSION AND CONCLUSIONS These data suggest that with ligature-induced peri-implantitis, both time and periodontal pathogens affect all surfaces equally after 60 days.

Bone conditioning to enhance implant osseointegration: an experimental study in pigs.

Abstract: Purpose Osseointegration of implants depends on time and the local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm and Zarb. The aim of the present study was to enhance osseointegration of implants through conditioning of the bone bed and to compare in this context the efficacy of bone condensation, an osteoinductive collagen (Colloss), and platelet-rich plasma (PRP). Materials and methods Porcine frontal skull bone was used for the preparation of Identical-size implant beds. Before placement of the implants (Ankylos, 3.5 x 4 mm), the implant beds were untreated (control) or conditioned with condensation, Colloss, or PRP. The animals were sacrificed after 2, 4, and 8 weeks. The specimens were then compared and analyzed by microradiography, and statistical analysis was performed using the Wilcoxon signed rank test. Results At the early observation times, significant effects on the sites of topical bone conditioning in comparison to the control group could be seen regarding the implant-bone interface (2 weeks: control 31%, Colloss 60%, condensation 73%, PRP 47%; 4 weeks: control 39%, Colloss 51%, condensation 40%, PRP 42%) and peri-implant bone density (2 weeks: control 31%, Colloss 48%, condensation 59%, PRP 39%; 4 weeks: control 47%, Colloss 53%, condensation 41%, PRP 50%). A leveling of the results between groups was found at 8 weeks (implant-bone interface: control 51%, Colloss 58%, condensation 55%, PRP 62%; peri-implant bone density: control 50%, Colloss 55%, condensation 51%, PRP 51%). Discussion Overall, bone condensation and Colloss apparently influenced bone formation process from the onset, but over the entire 8-week healing period, differences in bone formation were not significant Conclusion It can be stated that, in the initial healing phase, an effect of topical bone conditioning may be achieved by the different described methods.

Immediate placement of implants into periodontally infected sites in dogs: a histomorphometric study of bone-implant contact.

Abstract: Purpose The placement of implants allows for re-establishment of function and esthetics following tooth loss. Immediate implant placement is a relatively recent procedure and has advantages, such as reduced number of surgical procedures, preservation of alveolar bone, reduction of cost and period of edentulism, and increased patient acceptance. However, there are some specific contraindications for the technique, such as the presence of an infection caused by periodontal disease and periapical lesions. The objective of this study was to evaluate the percentage of bone-implant contact of immediate implants placed in periodontally infected sites. Materials and methods In the first phase, periodontitis was induced with ligatures in the mandibular premolars of 5 mongrel dogs, using the contralateral teeth as controls (received prophylaxis only). After 3 months, in the second phase of the study, 40 implants were placed in the alveoli of both experimental and control teeth. After a healing period of 12 weeks, the animals were euthanized, and the hemimandibles were removed, dissected, fixed, and prepared for histomorphometric analysis of percentage of bone-implant contact. The Mann-Whitney test was used for statistical analysis. Results The results of the histomorphometric analysis indicated mean bone-implant contact of 62.4% in the control group and 66.0% in the experimental group, a difference that was not statistically significant. Discussion Histomorphometric results revealed similar bone-implant contact in both groups, with no signs of infection. Conclusions It was concluded that periodontally infected sites may not be a contraindication for immediate implantation in this animal model system, if adequate pre- and postoperative care is taken.

Effects of alendronate on the removal torque of implants in rats with induced osteoporosis.

Abstract: Purpose: In this study, the removal torques of commercially pure titanium implants that had been implanted simultaneously with the start of treatment for osteoporosis were compared to those of a group without treatment and a healthy group. Materials and Methods: Rats treated by ovariectomy or sham surgery at the age of 12 weeks were used. Twenty-eight days after surgery, the rats treated by ovariectomy were divided into an alendronate-treated group and an untreated (ovariectomy-control) group. At the start of administration of alendronate, a titanium implant was placed in the distal metaphysis of the femur. After 1 month of administration of alendronate and a vehicle, removal torque, the percentage of bone-implant contact (BIC), and parameters of treatment using alendronate were measured. Results: The removal torque values were 10.1 ± 1.6 Ncm for the group of osteoporotic rats that had been administered alendronate and 6.4 ± 1.0 Ncm for the group of osteoporotic rats that did not receive alendronate, indicating that the removal torque was significantly higher in the former group than in the latter group. However, there was no significant difference between the alendronate-treated group and the healthy control group (ie, sham surgery) (9.3 ± 1.3 Ncm). Discussion and Conclusion: These results suggested that implant placement together with treatment of osteoporosis is possible in the ovariectomized rat model. (INT J ORAL MAXILLOFAC IMPLANTS 2003;18:218‐223)