A 5-year prospective clinical and radiographic study of non-submerged dental implants

Osseointegrated implants as anchors for various prosthetic reconstructions have become a predictable treatment alternative. It was expected that implants required submucosal placement during the healing period for successful tissue integration. However, it has been demonstrated that healing and long-term health of implants could be achieved with equal predictability in a 1-stage, non-submerged approach. This prospective 5-year study not only calculates implant success by life table analysis, but also evaluates the correlation between observed bone level changes with clinical parameters as measured by suppuration, plaque indices, bleeding indices, probing depth, attachment level and mobility. A total of 112 ITI dental implants were inserted in different areas of the jaws. Clinical and radiographic parameters were evaluated annually for 5 years, whereas a portion of the study group for which 6-year evaluations were available were included in the life-table analysis. The overall success rate after 5 years in service was 99.1%, while after 6 years it was reduced to 95.5% due to the fracture of 3 implants in 1 patient. The mean crestal bone loss experienced during the first year was 0.6 mm followed by an annual yearly loss of approximately 0.05 mm. No significant differences could be found between the amount of bone loss measured at each of the yearly follow-up visits. This suggests that statistically the followed implants did not show any radiographically measurable bone loss following the initial period of bone loss associated with implant placement and osseointegration. Low levels of correlation between the individual and cumulative clinical parameters with radiographically measured bone loss suggests that these parameters are of limited clinical value in assessing and predicting future peri-implant bone loss.     

A 10-year prospective clinical and radiographic study of one-stage dental implants

OBJECTIVE: The purpose of this prospective study was to evaluate one-stage dental implants clinically and radiographically after 10 years in function. MATERIAL AND METHODS: Twenty-five patients with a total of 68 implants [46 hollow screws (HS) and 22 hollow cylinders (HC)] who previously participated in 5-year prospective clinical study returned for a 10-year follow-up. For each patient, informed consent was obtained, medical and dental history was reviewed and soft and hard tissue conditions were evaluated using the modified plaque index, modified sulcus bleeding index, probing depth, suppuration, attachment level, distance from the implant crown margin to the coronal border of the peri-implant mucosa keratinized mucosa and periapical radiographs to calculate crestal bone-level changes. RESULTS: As expected, the mean crestal bone-level changes were the greatest in the first year following restoration placement, while only minimal changes were noticed in the subsequent years. HC implants showed a statistically significant higher mean crestal bone loss when compared with HS implants at year 10. Gender was also statistically significantly related to the mean crestal bone loss at years 1, 3, 5 and 10, with male subjects exhibiting more bone loss than female subjects. However, age and peri-implant soft tissue parameters showed low levels of correlation with the mean crestal bone-level changes, and proved to be weak predictors for the mean crestal bone loss at years 5 and 10. CONCLUSIONS: This study confirms that the mean crestal bone loss rates of the HS and HC implants are well within the clinically acceptable parameters. In addition, some of the clinical parameters could be used to assess and predict future crestal bone loss.     

A 5-year prospective study of Astra single tooth implants

AIM: To evaluate the AstraTech Implant ST (Molndal, Sweden) for single tooth replacement clinically and radiographically after 5 years in function. SUBJECTS AND METHOD: Fifteen patients (age range 16 to 48) with missing maxillary anterior teeth (6 central incisors, 8 laterals, 1 bicuspid) had four 13 mm and eleven 15 mm single tooth implants provided. All patients were seen at 4- to 6-monthly intervals for oral hygiene maintenance. Periapical radiographs using Rinn holders and a long cone technique were taken at the crown insertion and after 1 year, 3 and 5 years. RESULTS: No implant losses were observed in 14 of the 15 patients available for evaluation. No abutment screw loosening or soft tissue problems were observed. At crown insertion the mean bone level was 0.46 +/- 0.55 to 0.48 +/- 0.56 mm apical to the top of the implant neck and there were no statistically significant changes in the radiographic bone level over the 5 years of the study (0.36 +/- 0.37 to 0.43 +/- 0.46 mm at year 5). One crown was recemented after 18 months in function and 1 crown was replaced because of a fracture to the porcelain incisal edge. CONCLUSION: The Astra Tech Implants ST were highly successful in single tooth replacement and bone levels during 5 years of function were stable.     

A 3- to 6-year study of overdentures supported by hydroxyapatite-coated endosseous dental implants

PURPOSE: The purpose of this study was to evaluate the clinical effectiveness of hydroxyapatite-coated cylindrical implants to support overdentures. These implants were placed between 1990 and 1994 and have been followed up over a period of 3 to 6 years. MATERIALS AND METHODS: One hundred thirty-nine Calcitek dental implants were placed in 43 patients to support 14 maxillary and 30 mandibular overdentures. Standardized clinical review procedures were used. RESULTS: At exposure all the implants were found to be osseointegrated. To date only 7 implants (5%) have completely failed and two associated overdentures (5%) have been lost. The cumulative survival rate of all implants over 6 years was 92%. However, if failure is defined by the loss of more than 4 mm of cervical bone, 33 implants could be classified as being in the process of failing. Using these figures, interval success rates as low as 82% were found by year 6, and the cumulative success rate would fall to 39%. Maxillary survival and success rates were significantly lower than mandibular rates, at 38% and 10%, respectively, by year 5. CONCLUSION: Failure rates were higher in the maxillary arch, in poor quality bone, in smokers, and where implants were opposed by a natural dentition or an implant-supported prosthesis. The results suggest that the cervical bone level adjacent to the Calcitek cylindrical hydroxyapatite-coated implant failed to establish a steady state, particularly in the maxillary arch. Doubts remain regarding the long-term prognosis of these cylindrical implants.     

A 5-year prospective multicenter clinical trial of non-submerged dental implants with a titanium plasma-sprayed surface in 200 patients

Background: Endosseous dental implants are a popular treatment to replace missing teeth. Although many advances have occurred and affected the macrogeometry and surface characteristics of dental implants, among other aspects, it is important to document how the implants perform in patients over time. Such evaluations are helpful not only to document the clinical survival of the implants but also patient satisfaction over an extended period. Methods: A formal prospective multicenter human clinical was performed at five centers involving 200 patients and 626 implants. Specific inclusion and exclusion criteria were used and detailed data collected at specified times using case report forms. An independent study monitor reviewed all study data before entry into the study database. Two implant designs were used in two different clinical indications. A non‐submerged titanium plasma‐sprayed (TPS) hollow cylindrical implant with a smooth transgingival collar was evaluated in the maxillary anterior sextant and a non‐submerged TPS solid screw implant with similar collar in the mandible. Results: Over the course of the 5‐year clinical trial, there was one early failure occurring before definitive prosthesis delivery. Three late failures were documented, one occurring at each of the 6, 12, and 18 months postoperative visits. Life table analysis at 5 years revealed a 99.4% survival rate and a 92.5% success rate. Patient satisfaction was rated as good to excellent for 96.1% of implants in regards to esthetics after 5 years; 98.8% for appearance; and 99.4% for prosthesis comfort, ability to chew and taste, fit, and general satisfaction. No serious adverse events were reported. Conclusions: Implant success and survival was over 92% and 99%, respectively, in a formal 5‐year prospective multicenter clinical trial involving 200 patients and 626 non‐submerged TPS implants. These implants included hollow cylinder implants in the anterior maxilla and solid screw implants placed in the mandible. These findings document the predictability and patient satisfaction of tooth replacement using a non‐submerged surgical technique involving a tissue‐level, rough surfaced endosseous dental implant.     

A 5-year prospective study on small diameter screw-shaped oral implants

Alveloar ridges of limited dimensions could preclude the placement of dental implants of the regular dimension. Smaller diameter implants - narrow platform (NP) implants were commercially available to address this issue. The aim of the study was to determine the 5-year clinical performance of 3.3 mm diameter NP implants. Twenty-three machined screw-shaped NP implants were placed in nine patients (six males; three females) between 18 and 70 years of age. Clinical and radiographic examinations were performed annually for 5 years. Recognized implant success criteria was used. The criteria were based on the mean marginal alveolar bone loss, the placement of prosthesis of satisfactory appearance, and the absence of implant mobility, peri-implant radiolucency, pain, discomfort or infection. One implant failed at abutment connection. The remaining 22 implants were restored and functioned successfully according to the criteria. The mean marginal alveolar bone loss during the first year was 0.41 +/- 0.17 mm. The mean marginal alveolar bone loss between the second and fifth year was 0.03 +/- 0.06 mm. The success rate of NP implants according to a well-established set of criteria was 96%.     

A histomorphometric study of dental implants with different surface characteristics

PURPOSE

One of the major keys to achieve successful osseointegration of the implant is its surface properties. The aim of this study was to investigate the bone response to dental implants with different surface characteristics using the rabbit tibia model. Tricalcium phosphate (TCP) coated, anodic oxidized and turned (control) surfaces were compared.

MATERIALS AND METHODS

Seventy two implants were placed in the tibia of eighteen rabbits. Nine rabbits were sacrificed at 3 weeks of healing and the remaining nine were sacrificed at 6 weeks of healing. The bone-to-implant contact (BIC) and the bone volume density (BVD) were assessed by light microscope after 3 and 6 weeks of healing.

RESULTS

Statistical analysis showed that no significant differences in the BIC and BVD were observed between the different implant surfaces and the control group at 3 weeks and 6 weeks of healing. Data also suggested that the BVD of all the surfaces showed significant difference at 3 and 6 weeks.

CONCLUSION

The present study has showed that osseointegration occurred in all investigated types of surface-treated implants. In the current study all of the threads of the implants were observed to calculate BIC and BVD values (instead of choosing some of the threads from the bone cortex for example), which didn''t make BIC or BVD percentage values better than in the control group, therefore the clinical relevance of these results remains to be shown.     

Immediate functional loading of TiOblast dental implants in full-arch edentulous mandibles: a 3-year prospective study

Introduction: Implant-prosthetic rehabilitation of the completely edentulous mandible has evolved to a simplified procedure with shorter treatment time and survival rates of 95–100% depending on the implant system used.
Purpose: The aim was to evaluate the 3-year clinical success of Astra Tech TiOblast implants, functionally loaded on the day of surgery with a fixed full-arch bridge in the mandible.
Materials and methods: One hundred and twenty-five implants of 3.5–4 mm width and 11–17 mm length were installed in 25 edentulous mandibles of 15 female and 10 male patients. Implants were functionally loaded on the day of surgery with a provisional, acrylic, glassfibre reinforced, 10 unit bridge. After 3–4 months, the final 12-unit bridge was constructed. Radiographical bone loss was measured on peri-apical radiographs after 3, 12, 24 and 36 months.
Results: All implants were functional during the whole study period yielding a survival rate of 100%. None of the fixtures showed pain or mobility after manual torque with 20 N cm at the 3-month control. Mean radiographical bone loss after 3 months and 1, 2 and 3 years was 0.6 mm (SD 0.7), 0.8 mm (SD 0.8), 1 mm (SD 0.8) and 1.3 (SD 1) respectively, which was statistically significantly increasing up to 1 year.
Conclusion: Immediate loading of full-arch mandibular bridgework on five TiOblast implants offers a long-lasting clinical result with 100% fixture survival and stable bone-to-implant contact up to 3 years.     

Clinical outcome of Screw Vent implants. A 7-year prospective follow-up study

The clinical results of 85 Screw Vent implants are described with respect to 7-year success, including radiographically detectable bone loss, survival and prosthetic quality. The 1-year results of the same material have been reported previously (De Bruyn et al. 1992). Implants were considered as successful when they were meeting with the success criteria proposed by the European Academy for Periodontology. From the 85 implants originally installed, 16 failed during the 7-year interval (18.8%), 6 were unaccounted for (7%), 21 (24.7%) did not meet the success criteria yet survived and 42 implants (49.4%) were successful. The success rate was 65.2% for the mandibular and 43.5% for the maxillary implants. Implant failures were irrespective of implant length, smoking habits, prosthetic quality or oral hygiene level. From 24 patients with a corresponding number of 60 implants, radiographs were available for bone loss analysis. The mean bone loss after 7 years was 2.92 mm (range -0.5 to 6.3) 18 out of 60 examined implants (30%) showed unacceptable radiological bone loss beyond the critical value of 2.7 mm. Implant material analysis and histomorphometric analysis of a retrieved implant are discussed. In the present clinical study, the Screw Vent implant system does not meet the success criteria proposed by the European Academy for Periodontology. The ongoing bone loss increases the risk for future implant failures and peri-implant disease.     

A 4-year prospective clinical and radiological study of maxillary dental implants supporting single-tooth crowns using early and delayed loading protocols

Background: Recent studies have showed that immediate/early loading of dental implants is a clinically feasible concept with results similar to those for standard two‐stage procedures, especially in the mandible. However, there are only a few studies regarding the immediate/early loading of maxillary implants supporting single‐tooth crowns. Purpose: The aim of this study was to compare the clinical and radiological outcomes of early‐ and delayed‐loaded dental implants supporting single‐tooth crowns in the maxilla. Materials and Methods: Twenty‐nine patients were consecutively treated between 2000 and 2002 with 59 Brånemark System MK III TiUnite implants (Nobel Biocare AB, Göteborg, Sweden) in the maxilla. Two groups were formed according to the loading protocols. In the test group, definitive implant‐supported single crowns were delivered to 19 patients 6 weeks after the implant placement. In the control group, definitive implant‐supported single crowns were delivered to 10 patients 6 months after the implant placement. Clinical and radiographic parameters were recorded at baseline, 1 to 4 years. Implant stability measurements have only been performed at 4‐year follow‐up recall. Results: Overall, three implants were lost during the study period. Two implants were lost in the test group including 36 implants, which indicated a survival rate of 94.4%. One of the lost implants was replaced and then osseointegrated successfully. One implant was lost in the control group during the healing period, which indicated a survival rate of 95.7%. The average marginal bone loss was 1.11 mm for 56 implants after 4 years. There were no significant differences in marginal bone levels, insertion torque, and resonance frequency values between the two groups. Conclusion: The results of this study indicate that 6 weeks of early loading period for TiUnite‐surface titanium implants in the maxilla is reliable and predictable for this patient population and may offer an alternative to the standard loading protocol.     

A 10-year prospective study of ITI dental implants placed in the posterior region. I: Clinical and radiographic results

OBJECTIVES: To evaluate the long-term fixture success rate, crestal bone loss and peri-implant soft tissue parameters around ITI dental implants placed in the posterior region of partially edentulous patients. MATERIAL AND METHODS: A total of 192 ITI dental implants were consecutively placed in premolars and molars of 83 partially edentulous patients admitted for treatment at Geneva Dental School. All implants were restored by means of ceramic-to-metal fused fixed partial dentures and single crowns. Patients were followed as part of a prospective longitudinal study focusing on implant success. Surgical, radiographic and clinical variables were collected at the 1-year recall after implant placement and at the most recent clinical evaluation. RESULTS: The mean observation time was 6 years (range 5-10 years). Four implants failed, yielding a 10-year cumulative survival rate of 97.9%. The mean annual crestal bone loss was -0.04+/-0.2 mm. Hollow-cylinder implants displayed more crestal bone loss (-0.13+/-0.24 mm) than hollow-screw implants (-0.02+/-0.19 mm; P=0.032). Clinical parameters such as age, gender, implant length and bone quality did not affect crestal bone levels. Increase in recession depth (P=0.025) and attachment level (P=0.011) were significantly associated with crestal bone loss. CONCLUSIONS: ITI dental implants placed in the posterior jaw demonstrate excellent long-term clinical success. Hollow-cylinder implants seem to display a higher risk for crestal bone loss. Recession depth and attachment levels appear to be good clinical indicators of peri-implant bone loss.     

A 3-year prospective clinical and radiologic analysis of early loaded maxillary dental implants supporting single-tooth crowns

In this study, 19 patients were treated with 36 Br?nemark System MK III TiUnite implants in the maxilla. Definitive implant-supported single crowns were delivered to patients 6 weeks after implant placement. Clinical and radiographic parameters were recorded at baseline, and at 1, 2, and 3 years. Both implant and prosthesis success rates were 94% after 3 years. The average marginal bone loss was 0.97 mm after 3 years. The results of this study indicate that 6-week early loading of TiUnite surface implants in the maxilla was reliable and predictable for this patient population and may offer an alternative to the standard loading protocol.