Maxillary sinus floor augmentation using bioactive glass granules and autogenous bone with simultaneous implant placement. Clinical and histological findings

This clinical study was undertaken to: 1) evaluate the use of bioactive glass Biogran combined with autogenous bone as grafting material for maxillary sinus augmentation with simultaneous implant placement using radiography and histology; and 2) document the short-term post-loading success of implants inserted in sinus cavities augmented with this material. Unilateral or bilateral sinus augmentation was performed in 12 patients with 3-5 mm of alveolar crestal bone height in the posterior maxilla prior to grafting. The sinuses were grafted with bioactive glass mixed in a 4:1 ratio with autogenous bone. Simultaneously, 2-3 threaded titanium implants were inserted into the augmented sinuses. Second stage surgery was carried out 9 to 12 months post implantation. At abutment connection, 10 core biopsy specimens were taken from different grafted sites and evaluated histologically. All 27 implants were clinically stable at second stage surgery. A mean increase in mineralized tissue height of 7.1 +/- 1.6 mm was evident when comparing the pre-surgical CT scans with those performed 9-12 months following the sinus augmentation procedure. Evaluation of the cores yielded a mean of 30.6 +/- 5.7% of bone tissue in the grafted sites. One implant failed during the prosthetic phase while the remaining 26 implants were stable 12 months post loading. This study suggests that Biogran/autogenous bone graft combination used in one-stage sinus augmentation yields sufficient quality and volume of mineralized tissue for predictable simultaneous implant placement in patients with 3-5 mm of bone height prior to grafting.     

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

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.     

Marginal bone loss pattern around hydroxyapatite-coated versus commercially pure titanium implants after up to 12 years of follow-up

PURPOSE: The purpose of this study was to compare the marginal bone loss (MBL), complications, and 12-year survival rates of commercially pure titanium (cpTi) and hydroxyapatite (HA)-coated implants placed in the maxilla. MATERIALS AND METHODS: The study group consisted of 120 patients (77 women, 43 men) treated from 1988 to 1997. A total of 388 implants (156 cpTi and 232 HA-coated) were placed in the maxilla. There were 126 immediate (32.5%) and 262 (67.5%) nonimmediate implants. Patients were evaluated annually. Mean follow-up was 60 +/- 32.3 months. MBL was measured on radiographs using the implant threads as the dimensional reference. MBL, complications, and 12-year survival and success rates were correlated with implant coating, time of implantation, implant dimensions, and position in arch. RESULTS: Total mean MBL was 1.07 +/- 2.16 mm. MBL was significantly lower with cpTi implants (0.55 +/- 1.04 mm) compared to HA-coated implants (1.51 +/- 2.71 mm) (P < .001). No statistical difference in regard to MBL was found between immediate and nonimmediate implants (0.86 +/- 1.8 mm vs 1.16 +/- 2.3 mm). The total 12-year survival rate was 91.4%. HA-coated implants had a significantly higher 12-year survival rate than cpTi implants (93.2% vs 89%; P < .03). Nonimmediate implants had a significantly higher failure rate (8.2%) than the immediate implants (1.3%) (P < .009). No correlation was found between type of implant coating and late implant failure. DISCUSSION: Immediate implants can serve as a predictable option, providing higher survival and success rates. HA-coated implants tended to fail less during the surgical phase, but had higher mean MBL compared to cpTi implants. CONCLUSIONS: HA-coated implants had greater MBL than cpTi implants but a higher 12-year survival rate. Immediate implants had a lower failure rate than the nonimmediate implants in this study population.     

Impact of implant surface and grafting protocol on clinical outcomes of endosseous implants

PURPOSE: The objectives of this study were to (1) evaluate the survival of implants placed in maxillary sinuses augmented with a 70:30 mixture of autogenous bone and anorganic bovine hydroxyapatite (Bio-Oss) at 1 and 5 years, (2) observe the difference in survival rate between 1-stage and 2-stage procedures, and (3) compare the survival rate of rough-surfaced implants with that of machined implants. MATERIALS AND METHODS: A total of 30 consecutively patients (48 sinuses) with Cawood and Howell Class V and VI atrophy were evaluated. Lateral osteotomy techniques were used in all cases. Implants were placed either simultaneous with grafting (1-stage procedure) or after a delay (2-stage procedure), depending on the amount of residual bone. A 70:30 mixture of autogenous bone and anorganic bovine hydroxyapatite was used as the graft material. All patients were followed up at 1 year after prosthetic loading, while a limited group of these patients was followed up to 5 years. RESULTS: In 8 patients where the residual crestal bone under the sinus floor assessed by computed tomography was at least 4.5 mm (mean, 5.3 mm), the 1-stage procedure was used for 11 sinus elevations and 32 implants. In 22 patients where the residual crestal bone was less than 4.5 mm (mean, 2.5 mm), the 2-stage procedure was used for 37 sinus elevations and 108 implants. For the 140 implants placed, the overall survival rate was 95.7% at the healing abutment surgery, and the cumulative survival rate was 94.9% at 1 and 5 years. The type of surgical technique was significantly associated with implant failure (P < .05); implants placed using the 1-stage procedure showed a failure rate of 12.5%, while implants placed with the 2-stage procedure had a failure rate of 2.8%. No significant difference in survival rate was observed with respect to implant surface. CONCLUSIONS: A high survival rate was achieved when sinus elevation was performed with a combination of autogenous bone and anorganic bovine hydroxyapatite, even where a minimal amount of residual crestal bone was present. The survival rate was improved when implants were placed after a healing period.     

Maxillary sinus reconstruction with calvarium bone grafts and endosseous implants.

PURPOSE: The objectives of this study were 1) to evaluate the survival rate for implants placed in maxillary sinuses augmented with autogenous calvarium bone graft and 2) to evaluate the feasibility, complications, and morbidity of this technique as well as patient satisfaction. PATIENTS AND METHODS: Seventy-nine maxillary sinuses in 58 patients were reconstructed with calvarium grafts between 1992 and 2002 with more than 1 year of prosthetic loading. Two hundred twenty-three implants were placed 3 to 11 months after grafting. Bone levels were measured preoperatively after grafting and 1 year after prosthetic loading. RESULTS: Successful healing was observed in 77 sinuses (97.4%), and 2 patients (2.6%) showed dehiscence and graft loss. All implants integrated; 211 (94.6%) were used for fixed restorations and 12 implants (5.4%) were used in 2 patients for overdentures (6 implants each). The fixed prosthesis survival rate was 100% after 1 year of loading and remained successful in all cases during the follow-up. At the second stage of surgery, crestal bone loss was measured with a caliper. No crestal bone loss was observed in 210 implants (94%). However, in 13 implants (6%), a crestal bone loss between 1.5 and 2.5 mm was observed, but no further bone loss occurred during the follow-up, as shown on panoramic radiography. Panoramic radiograph measurements showed a total bone height (alveolar bone plus grafted bone) of more than 15 mm in all sinuses and of more than 20 mm in 25 sinuses (32.4%) with a mean of 18 mm. Bone levels were maintained during the follow-up. CONCLUSIONS: 1) Calvarium provides graft material of excellent quality and quantity. 2) Satisfactory results can be obtained with implants placed after sinus augmentation with calvarium bone graft as shown in this study with no implant failure. Bone levels, implants, and bridge survival were maintained during the follow-up.     

Autologous bone graft to augment the maxillary sinus in conjunction with immediate endosseous implants: a retrospective study up to 5 years.

This study reports the successful use of osseointegrated implants to replace posterior teeth combined with the autogenous bone graft technique in the sinus. Preliminary data (1 to 6 years experience) of this one-stage procedure are presented. A total of 33 patients were treated--44 sinus grafts were augmented with bone from the anterior iliac crest. Reconstruction was completed with ceramic fixed partial dentures, and there was a follow-up of 3 to 80 months (mean 40.2 months) after loading. None of the 44 sinus grafts was lost. Of the 121 implants placed, eight failed, resulting in a failure rate of 6.6% and a cumulative failure rate of 6.8%. Of the 44 prostheses placed in the 44 sinuses, one failed, resulting in a prosthesis stability of 97.7%. Complications were encountered in three patients (three sinuses, eight implants); treatments were administered, symptoms subsided, and the implants integrated in two patients (two sinuses, six implants). One patient lost the two implants and the prosthesis, but the graft integrated. No other complications have since occurred. The results compare favorably with previous reports in terms of implant survival and stability. The implant survival rate approached that of implants placed in uncompromised maxillary bone.     

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone.

PURPOSE: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. PATIENTS AND METHODS: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. RESULTS: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. CONCLUSIONS: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption.     

A comparison of hydroxyapatite (HA) -coated threaded,HA-coated cylindric,and titanium threaded endosseous dental implants

PURPOSE: The purpose of this study was to compare the success of hydroxyapatite (HA) -coated and machined titanium (Ti) implants in a 5-year randomized, controlled clinical trial conducted at 2 centers. MATERIALS AND METHODS: Each of 120 edentulous patients received HA-coated threaded, HA-coated cylindric, and machined Ti threaded implants in a randomized design using 5 or 6 implants. Digital radiographs allowed for yearly measurements of bone loss. Calibrated clinicians also measured mobility, Gingival Index, Plaque Index, probing depth, and recession. A Kaplan-Meier analysis was used to compare the proportion of ailing implants (defined as less than 2 mm of alveolar bone loss over 5 years) for each type of implant design. The criteria employed to assess implant outcome included the need for successful implants to lose less than 2 mm of bone support over the 5 years following placement of the prosthesis. RESULTS: This analysis revealed that 95.2% of machined Ti threaded implants and 97.92% of HA-coated threaded implants were successful, while 99.0% of HA-coated cylindric implants experienced less than 2 mm of bone loss (P < .06). DISCUSSION: All types of implants placed in this study had success rates above 95%. CONCLUSION: Over 5 years, the success rate tended to favor HA-coated implants.     

The use of hydroxyapatite bone cement for sinus floor augmentation with simultaneous implant placement in the atrophic maxilla. A report of 10 cases

BACKGROUND: Dental implant placement associated with sinus floor augmentation in a severely atrophic maxilla can be performed in a 1- or 2-stage surgical procedure, depending on the height of the residual alveolar bone. A minimum of 4 to 5 mm is recommended for a 1-stage procedure. METHODS: This clinical study describes the use of hydroxyapatite (HA) bone cement to stabilize HA-coated cylindrical implants placed simultaneously during sinus augmentation in 100 patients where insufficient bone volume did not allow primary implant stability. A total of 26 HA-coated dental implants were inserted in 100 grafted sinuses of 10 patients. RESULTS: None of the cases presented any difficulty in achieving initial stabilization and parallelism. No clinical complications of the sinuses were evident. Prior to exposure, radiographic evaluation revealed the implants embedded in a densely homogeneous radiopaque mass. At second-stage surgery, there was no clinical evidence of crestal bone loss around the implants. All implants were clinically osseointegrated. All patients received fixed implant-supported prostheses. Mean follow-up was 18 months (range 12 to 24 months). CONCLUSIONS: According to this preliminary study, the hydroxyapatite bone cement appears to hold great promise as a grafting alloplastic material for sinus floor augmentations. Its main advantage is its ability to provide initial stability required for osseointegration and proper implant location and parallelism. Further clinical and histological studies are required before it can be recommended for routine use in sinus lift procedures.     

Survival Rate for Implants Placed in the Posterior Maxilla With and Without Sinus Augmentation: A Comparative Cohort Study

Background: The reduced bone height and proximity of the maxillary sinus are the most common limitations for placement of dental implants in the posterior maxilla. Reconstruction of the atrophic posterior maxilla can be performed with a sinus augmentation procedure. The aim of this cohort study is to compare the survival rate of implants placed in augmented sinus to implants placed in native bone in the posterior maxilla. Methods: This study was designed as a prospective cohort study and included consecutively treated patients. Patients who required the sinus augmentation (test group) were treated according to the two‐stage technique. Patients were scheduled for follow‐up evaluation at 3, 6, and 12 months after implant placement and then every 6 months for ≤6 years. Results: One hundred and five patients with 393 implants were enrolled in the study. Two hundred and one implants were placed after preliminary sinus floor grafting in 41 patients. The control group contained 64 patients with 192 implants that were placed in pristine bone of the posterior maxilla. The cumulative implant survival rates were 86.1% and 96.4%, respectively. The difference between the two groups was highly significant (P <0.005). Conclusions: These findings show that implants placed in augmented sinuses had a lower survival rate compared to implants placed in pristine bone. All the implant failures in the augmented sinuses occurred before the prosthetic rehabilitation. Moreover, it should be considered that most of the failures were observed in few patients, thus suggesting cluster behavior.     

Three-year analysis of tapered screw vent implants placed into maxillary sinuses grafted with mineralized bone allograft

With an increase in the number of patients presenting for dental implant treatment, it is becoming more common for clinicians to encounter inadequate bone volume. Several surgical techniques have been advocated for placing dental implants in the posterior maxilla, including the lateral window sinus elevation technique. This article reports the results of implants placed into maxillary sinuses grafted with particulate mineralized cancellous bone allograft alone or in combination with resorbable hydroxyapatite over a 3-year period. A total of 56 sinuses were grafted, and 136 dental implants were placed into the grafted sites after a 4- to 8-month healing period. All reentries revealed a bony hard structure acceptable for osteotomy preparation. Of these implants, 124 have been restored with fixed prosthesis and 12 with removable overdentures for a total of 136 loaded implants. A total of 3 implants required removal (failure) resulting in a 97.7% implant success rate (2.3% failure rate). A conclusion was made that mineralized human allograft, placed into lateral window sinus elevations, is a clinically predicable method acceptable for implant placement and restoration.     

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Evaluation of autogenous bone combined with porous hydroxyapatite.

The aim of this study was to evaluate clinically, histologically, and histometrically the use of autogenous bone combined with porous hydroxyapatite (Interpore 200®) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. After a healing period of 3 months. maxillary sinus augmentation procedures were performed in each monkey, and the sinuses were grafted with autogenous bone from the monkeys' tibia mixed in a 3:1 ratio with porous hydroxyapatite. At the same time. 2 pure titanium plasma-sprayed IMZB cylinder implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received similar treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants unloaded group and delayed implants unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation. The porous hydroxyapatite granules appeared integrated with the newly formed bone. Histometric analyses revealed that delayed implant placement resulted in a greater amount of direct mineralized bone-to-implant contact in the augmented area than the simultaneous implant placement. Furthermore, the percentage of direct mineralized bone-to-implant contact was far more significant in the residual bone than in the augmented area. It was concluded that the autogenous bone/porous hydroxyapatite graft combination enhanced bone formation and mineralized bone-to-implant contact in the augmented sinuses and that the delayed implant placement may be favorable for sinus augmentation procedures.     

Self-bone graft and simultaneous application of implants in the upper jawbone. (Fit lock technique)

The implant-supported rehabilitation ofposterosuperior sectors may be sometimes conditioned by the pneumatization of the para-nasal sinuses, which decreases the possibility of implant placement when the bone height is < or = 4 mm. (prerequisite for primary stabilization). Sinus lift surgery with simultaneous application of implants is the procedure which provides the best chance of success compared to the application of the filling material only. There are many surgical techniques which combine autogenous bone grafting (ilium crest, calvaria,fibula) with implant placement. The objective of this report is to present a new technique which aims to minimize invasive bone grafting and patient morbidity. The authors performed a longitudinal study on 21 cases with a 94.5% success rate, exemplified by one clinical case. The advantages of this technique are: 1) Functional and anatomical recovery of the jaw cavity. 2) Simultaneous application of implants when the bone is < or = 4mm. 3) Reduction of surgical times. 4) Reduced patient morbidity. 5) Local anesthesia.     

Implant surface coating and bone quality-related survival outcomes through 36 months post-placement of root-form endosseous dental implants

Survival rates from placement to 36 months were reported for the ongoing Dental Implant Clinical Research Group studies of root-form endosseous dental implants. Failure rates for all implants were similar in bone qualities 1 and 2 (6.2% and 6.7%, respectively) and slightly higher in bone qualities 3 and 4 (8.5% and 8.7%, respectively). Hydroxyapatite (HA)-coated implants had an overall failure rate of 3.9% over 36 months in all bone qualities combined, while non-coated implants had a 13.4% failure rate for the same parameters. For each bone quality, there was a significant difference in implant survival for the non-coated implants (P < 0.01). The highest failure rates for non-coated implants were in bone qualities 3 and 4 (19.1% and 25.5%, respectively). No major difference in survival was found for HA-coated implants placed in each bone quality. Possible reasons for the differences in survival are discussed.     

Effect of Maxillary Sinus Membrane Perforation on Vital Bone Formation and Implant Survival: A Retrospective Study

Background: The maxillary sinus augmentation procedure (SAP) using the lateral window technique has been documented to be a highly predictable procedure. However, the most common intraoperative complication has been reported to be maxillary sinus membrane perforation (MSMP). The present study evaluates the percentage of vital bone and implant survival in sinuses that had perforations repaired during surgery versus a non‐perforated sinus group. Methods: Data were obtained retrospectively from an Institutional Review Board–approved anonymous database at New York University, Kriser Dental Center, Department of Periodontology and Implant Dentistry, New York, New York, from 23 patients who had undergone SAP with a total of 40 treated sinuses. Sinuses were grafted with mineralized cancellous bone allograft, anorganic bovine bone matrix, or biphasic calcium phospate. Perforation complications occurred in 15 sinuses with 25 non‐perforated sinuses. All perforations were repaired during surgery with absorbable collagen membrane barriers. Histologic cores were taken from all treated sinuses 26 to 32 weeks after surgery. The implant success rate of 79 placed implants was recorded. Results: The average percentage of vital bone was 26.3% ± 6.3% in the perforated (repaired) sinuses versus 19.1% ± 6.3% in the non‐perforated sinuses. The differences were statistically significant (SS). The implant success rate was 100% (35 of 35) compared to 95.5% (43 of 45) in the perforated/repaired vs. non‐perforated sinuses, respectively. There was no SS difference in implant failure rates. Conclusions: The augmented sinuses in this study that exhibited MSMPs that occurred during the SAP (which were treated during surgery) show SS greater vital bone percentages compared with the non‐perforated sinus group. There were no SS differences in implant survival in the perforated versus non‐perforated groups. In this study, sinus MSMPs, when properly repaired during surgery, do not appear to be an adverse complication in terms of vital bone production or implant survival.     

Maxillary sinus augmentation using a peptide-modified graft material in three mixtures: a prospective human case series of histologic and histomorphometric results

This prospective study assessed vital bone quality and quantity after grafting maxillary sinuses with anorganic bone mineral containing a cell binding peptide (ABM/P-15) in combination with DFDBA (Mix I), hydrogel/ABM/P-15 (Mix II), or PRP (Mix III). Fifteen maxillary sinuses in 12 patients were grafted with the ABM/P-15 mixtures and after 4 to 5 months, cores were taken and analyzed histologically and histomorphometrically. Fifty-nine screw-type implants were placed. Mixes containing a spacer material (Mix I and II) produced greater average vital bone, more mature bone, and more interconnected bone bridges from the cortical (oral) end to the most apical portion, compared to a mix that lacked a spacer material (Mix III). None of the 59 implants failed with any graft material up to 5 months following implant placement. The study demonstrates that new trabecular bone is formed after grafting ABM/P-15 in the sinus floor; that more vital bone is formed when ABM/P-15 is mixed with a spacer material than without; and that implants can be successfully placed.     

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss®) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Mucaca mulattu) the 1st 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3–4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.     

Clinical report with up to 4 years of follow-up on a cervically modified stepped screw-type implant

PURPOSE: In 1998, a modification of the macrostructure of the Frialit-2 implant in the cervical region was introduced to stabilize peri-implant bone. Limited data are available on the clinical effect of this modification. Therefore, the soft-tissue situation, marginal bone loss, and implant failure rate were analyzed after 4 years of clinical experience with the modified Frialit-2 Synchro implant. MATERIALS AND METHODS: From 1998 to 2001, 190 cervically modified implants were placed and documented prospectively in 58 patients. Of these implants, 147 were placed in original jaw bone, 22 in areas augmented with local osteoplasty, and 21 in iliac crest bone graft. The main indications for implantation were an atrophic edentulous alveolar crest (n = 99) and support for a partial denture (n = 39), followed by restoration of a shortened dental arch (n = 28) and single tooth replacement (n = 24). In a special clinical examination, 39 patients with 134 implants were investigated. RESULTS: The average in situ time of the 134 implants was 23.1 months. Failing osseointegration (n = 10), peri-implantitis (n = 1), and tumor resection (n = 3) in 8 patients resulted in the failure of 14 of 190 implants (7.4%). One patient with 4 implants died (2.1%). Currently, 3 patients with a total of 6 implants have been lost to follow-up (3.1%), and 166 implants remain in situ (87.4% of 190). DISCUSSION: Using different implant success criteria, success rates of 88.8% and 82.8% were calculated. CONCLUSION: Based on the results, the Frialit-2 Synchro implant appears to be a useful implant system for the indications analyzed.     

A 3 to 4 year study of single tooth hydroxylapatite coated endosseous dental implants.

OBJECTIVE: To evaluate the clinical effectiveness, common complications and maintenance associated with hydroxylapatite (HA) coated cylindrical implants when used to support single crowns. DESIGN: A prospective medium term clinical study of the Calcitek HA-coated implant. SETTING: Implant placement, crown fabrication and follow-up procedures were carried out at the Leeds Dental Institute, between 1990 and 1998. SUBJECTS AND METHOD: 26 patients (33 implants) participated in the trial. They were referred from general dental practitioners because of their suitability for single tooth implant placement. MAIN OUTCOME MEASURES: The implants were assessed using recognised clinical review procedures e.g. radiographs and soft tissue assessments. RESULTS: At exposure there was 100% implant integration. The cumulative survival rate over 4 years was 100%. In five implants there was cervical bone loss of more than 4 mm and these were classified as failing. This gave an overall cumulative success rate of 58% by year 4. CONCLUSION: The Calcitek HA-coated single tooth implant shows exceptionally high initial integration however, the longer term results suggest that the cervical bone level adjacent to the implant failed to establish a steady state. Doubts remain regarding the long-term prognosis of these cylindrical HA-coated implants.