Tissue alterations at implant-supported single-tooth replacements: a 1-year prospective clinical study

Objectives: The aim of this prospective study was to evaluate dimensional alterations of the peri‐implant tissues at single‐tooth restorations from the time of implant placement to 1‐year post‐loading. Material and methods: Eleven patients, aged 18–36 years, subjected to single‐tooth replacements with implant‐supported restorations (Brånemark implant^® system) in the maxillary anterior region were included in the analysis. The implant installation was performed as a two‐stage procedure with a 6‐month healing interval. Bone dimensions were determined by direct assessments immediately following implant placement and at abutment connection. The prosthetic restoration was placed approximately 1 month after abutment surgery. Radiographic and clinical examinations were performed at crown placement and at 1‐year post‐loading. Assessments of the soft tissues at the implant site and at the neighboring teeth were performed before and during implant placement, before abutment connection, after crown placement and at the 1‐year follow‐up examination. Mean values and standard deviations were calculated for each variable and interval, with the subject as the statistical unit. Results: At the time of abutment connection, a mean loss of bone height at the facial and lingual aspect of the implant amounting to 0.7–1.3 mm (P<0.05) was recorded, whereas no significant change was noted at proximal sites. A mean reduction of 0.4 mm of the labial bone thickness was observed between implant placement and the second‐stage surgery. The radiographic bone‐to‐implant level showed a mean loss of 0.9 mm between abutment connection and crown placement (P<0.05) and a further 0.7 mm loss at 1 year (P<0.05). The thickness of the labial mucosa was increased at crown placement followed by a slight remission at 1 year. During the corresponding interval, a mean apical displacement of the labial soft tissue margin of 0.6 mm had taken place (P<0.05). A papilla fill of ≥50% was observed at a frequency of 32% at crown placement and 86% at 1 year. Conclusions: The results demonstrated that following implant surgery remodeling takes place, which is manifested in diminished bone dimensions, both horizontally and vertically, at the facial aspect of the implant. The observed soft tissue alterations after the crown placement may affect the esthetic appeal of the restorative therapy.     

Experimental zirconia abutments for implant-supported single-tooth restorations in esthetically demanding regions: 4-year results of a prospective clinical study

PURPOSE: This prospective clinical study evaluated an experimental implant abutment made of densely sintered zirconia with respect to peri-implant hard and soft tissue reaction as well as fracture resistance over time. MATERIALS AND METHODS: Twenty-seven consecutively treated patients with 54 single-tooth implants were included. Zirconia abutment ingots were individually shaped and set on the implants with gold screws. All-ceramic (Empress I) crowns were cemented using a composite cement. At the 1- and 4-year examinations, reconstructions were evaluated for technical problems (fracture of abutment or crown, loosening of abutment screw). Modified Plaque and simplified Gingival Indices were recorded at implants and neighboring teeth, and peri-implant bone levels were radiographically determined. RESULTS: All but 1 of the 27 patients with 53 restorations could be evaluated at 1 year, and 36 restorations in 18 patients were evaluated 4 years after abutment and crown insertion. The median observation period for the reconstructions was 49.2 months. No abutment fractures occurred. Abutment screw loosening was reported for 2 restorations at 8 months and 27 months, respectively. Mean Plaque Index was 0.4 (SD 0.6) at abutments and 0.5 (SD 0.6) at teeth; mean Gingival Index was 0.7 (SD 0.5) at abutments and 0.9 (SD 0.5) at teeth. Mean marginal bone loss measured 1.2 mm (SD 0.5) after 4 years of functional loading. CONCLUSION: Zirconia abutments offered sufficient stability to support implant-supported single-tooth reconstructions in anterior and premolar regions. The soft and hard tissue reaction toward zirconia was favorable.     

Implant-supported single-tooth restorations: a 5-year prospective study

BACKGROUND: Comparatively few studies are available reporting at least 5 years of follow-up data of implant-supported single-tooth replacements. OBJECTIVE: To evaluate prospectively the 5-year outcome of implant-supported single-tooth prosthetic restorations. MATERIAL AND METHODS: Forty subjects (mean age 41 years), 23 males and 17 females, who required single-tooth prosthetic replacement for a missing tooth were recruited. A total of 45 self-tapping implants (Astra Tech ST-implants)--40 in the maxilla and five in the mandible--were installed in a two-stage procedure. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographic examinations were performed at the completion of the prosthetic treatment and once a year during a 5-year follow-up period. The analysis of peri-implant bone level alteration was performed on subject and implant levels and by the use of analysis of variance and binary logistic regression. RESULTS: Three patients were lost during the 5 years of follow-up. One implant was lost after 2.5 years in function and another four implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 2.6% (subject level) and 2.3% (implant level). The mean loss of marginal bone at the implants during the first year in function was 0.06 mm (SD 0.67) on the subject level and 0.02 mm (0.65) on the implant level. During the subsequent 4 years the annual change in peri-implant bone level amounted to -0.02 mm (0.22) on both subject and implant levels. Thus, the mean total bone level change over the 5-year interval was -0.14 mm (1.04) on subject level and -0.11 mm (1.00) on the implant level of analysis (p>0.05). The frequency of implants with a 5-year bone loss of > or =1 mm was 13%. Approximately 50% of the implants demonstrated no bone loss. CONCLUSION: The present clinical trial on single-tooth replacements with the Astra Tech implant system demonstrated that the bone loss during the first year of function as well as annually thereafter was small.     

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.     

Evaluation of aesthetics of implant-supported single-tooth replacements using different bone augmentation procedures: a prospective randomized clinical study

OBJECTIVES: The aim of this study was to evaluate the aesthetics of implant-supported single-tooth replacements using different augmentation procedures in a prospective study with the use of an objective rating index and with a subjective patient questionnaire, and to compare the results with each other. MATERIAL AND METHODS: Ninety-three patients with a single-tooth gap in the anterior zone of the maxilla were selected for the study. All patients had a local bone defect that needed augmentation before placement of an endosseous implant with sufficient initial stability. Aesthetics of the implant-supported crown and adjacent mucosa was rated by a prosthodontist 1 year after placement of the porcelain crown. Aesthetics was rated using the Implant Crown Aesthetic Index. A subjective appreciation of the final result was assessed with a patient questionnaire. RESULTS: The Implant Crown Aesthetic Index reveals a mean overall score of 4.8, with an acceptable result in 66% of the cases. Results of the satisfaction questionnaire reveal a mean overall score of 8.5 with an acceptable result in 100% of the cases. There is no correlation between results of the Index and the questionnaire for the overall and the crown score. The patients' opinion and the professionals' opinion about the peri-implant mucosa do show a significant correlation. CONCLUSIONS: The peri-implant mucosa is rated as less satisfactory than the implant-supported crown by both the dental professional and patients. The dental professional was less satisfied with respect to the total result and results of the crown than the patients.     

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.     

后牙种植单冠修复后局部咬合变化的四年前瞻性临床研究

目的:定量分析后牙种植单冠修复后4年患者口内局部 力分布与咬合时间的变化规律,为种植修复体的咬合设计、调整和长期维护提供参考。 方法:前瞻性收集2012年12月至2013年12月于北京大学口腔医学院·口腔医院修复科行后牙种植单冠修复的患者,分别于修复后2周和3、6个月以及1、2、3、4年复查,采用...     

Removable four implant-supported mandibular overdentures rigidly retained with telescopic crowns or milled bars: a 3-year prospective study

Purpose: The present study evaluated implant survival/success rate, peri‐implant parameters and prosthodontic maintenance efforts for four implant‐supported mandibular overdentures (IOD) rigidly retained on either milled bar or double crowns (telescopic) attachments. Material and methods: In a randomized prospective trial, 51 patients with edentulism received four mandibular interforaminal implants and complete maxillary dentures. For IOD, rigid denture stabilization was chosen randomly selecting 26 patients for milled bars (group I) and 25 patients for double (telescopic) crowns (group II). During a 3‐year follow‐up period, implant survival/success, peri‐implant parameters (marginal bone resorption, pocket depth, plaque‐, bleeding‐, gingival index [BI and GI], calculus) and prosthodontic maintenance efforts were evaluated and compared between both retention modalities used. Results: Forty‐five patients (23 group I, 22 group II) were available for a 3‐year follow‐up (dropout rate: 11.8%) presenting a high implant survival/success rate (100%). Peri‐implant marginal bone resorption, pocket depth as well as BI and GI did not differ for both rigid retention modalities. However, annually higher values for plaque‐ (NS) and calculus index (P<0.035) were noticed for the bar (group I) than for the telescopic crown (group II) attachments. Prevalence of prosthodontic maintenance did not differ between both retention modalities (group I: 0.41/maintenance efforts/year/patients vs. group II; 0.45 maintenance/efforts/year/patients). However, prosthodontic adaption for handling mechanism showed benefits for the bar retention. Conclusion: Rigid anchoring of IOD retained either by bar or telescopic attachments showed high implant success rates and minor prosthodontic maintenance efforts regardless of retention modalities used. Stable denture retention presented healthy peri‐implant structure for implants in bar and telescopic anchoring systems. Drawbacks such as higher plaque/calculus for bar retention and less favorable handling properties (output) for telescopic crown attachment leave the decision on the selection at the discretion of the clinician. To cite this article:
Krennmair G, Sütö D, Seemann R, Piehslinger E. Removable four implant‐supported mandibular overdentures rigidly retained with telescopic crowns or milled bars: a 3‐year prospective study.
Clin. Oral Impl. Res. 23 , 2012 481–488.
doi: 10.1111/j.1600‐0501.2011.02169.x     

A 3-year prospective study of a single-tooth implant--prosthodontic complications

PURPOSE: The objective of this 3-year prospective study was to evaluate a new titanium dental implant system and to identify any mechanical concerns or deficiencies in its design. MATERIALS AND METHODS: One periodontist placed 78 single-tooth implants in 59 subjects. One restorative dentist using one dental laboratory fabricated all of the crowns. Each patient then was seen eight times by the authors for clinical, radiographic, and laboratory testing. RESULTS: One of the 78 implants failed to integrate and was removed. There were no structural failures per se, although six of the cemented crowns and six of the restorative posts and cores (abutments) became loose. On a few occasions, the emergence profile was esthetically or functionally unsatisfactory. The manufacturer introduced changes in design and created an adjustable torque wrench, a torque-adjusting beam scale, and die replicas of the abutment posts in response to the identified concerns. CONCLUSION: The clinical trial helped in the development of an implant system that is user friendly, cost effective, and able to withstand parafunctional forces in the absence of antirotational features.     

Computer-aided direct all-ceramic crowns: preliminary 1-year results of a prospective clinical study

The objective of this study was to investigate the clinical performance of: (1) adhesively placed Cerec crowns with reduced stump preparations, and (2) Cerec endo crowns. The crowns were examined at baseline using modified USPHS criteria in 20 patients with 10 Cerec crowns with reduced stump preparations and 10 Cerec endo crowns. All crowns had been produced chairside with the Cerec 3 CAD/CAM method using the function mode. The crowns were machined from Vita Mk II feldspathic ceramic blocks, polished manually, and placed with dual-curing composite luting agent using a functional adhesive. After 1 year, a follow-up examination of the crowns was conducted; all 20 Cerec crowns were rated with a clinically acceptable A or B rating. Fractures or loss of retention were not observed. The method of producing and placing all-ceramic crowns with reduced stump preparations and endo crowns chairside in one appointment can be implemented successfully in private practice.     

Comparison of implant versus tooth-supported zirconia-based single crowns in a split-mouth design: a 4-year clinical follow-up study

Objectives

This study aims to evaluate the 4-year clinical performance of tooth versus implant-supported single-unit zirconia crowns (LAVA?) placed on posterior region.

Materials and methods

Twenty-four patients (10 men and 14 women) who had received 48 single crowns (24 implant-supported and 24 tooth-supported) from January 2007 to December 2009, were included. California Dental Association (CDA) quality assessment system, plaque and gingival index scores were used to evaluate the performance of the crowns at baseline and at all follow-up examinations.

Results

During the follow-up period, no fracture of zirconia coping has occurred. Major complication was chipping in three patients that required a new crown fabrication. Except for the failure ones, all crowns in both groups were rated as satisfactory at the follow-up examinations based on the CDA quality assessment criteria. There were no statistically significant differences between tooth and implant-supported crowns in terms of periodontal parameters.

Conclusions

The present 4-year follow-up clinical study demonstrates that single-unit tooth- and implant-supported zirconia crowns have similar prosthetic and periodontal outcomes.

Clinical relevance

Single-unit implant or tooth-supported zirconia crowns may be considered acceptable treatment modalities for restoration of either missing or compromised posterior teeth

     

Fabrication of a screw-retained, implant-supported, provisional prosthesis: a clinical report

An implant supported conversion prosthesis may provide patients with the advantages of a fixed prosthesis immediately after a surgical procedure. This report describes the fabrication of an implant-supported conversion prosthesis using a metal framework fabricated by estimating the implant positions before second-stage surgery.     

磨牙缺失颌间距离不足种植体支持的螺丝固位一体冠修复临床分析

目的:观察磨牙缺失颌间距离不足种植体支持的螺丝固位一体冠修复体的临床效果.方法:选取376例磨牙缺失、颌间距离不足,不能满足常规种植修复5～7 mm的修复空间的患者,共计507颗种植体,采用常规种植一期手术,并运用种植体支持的螺丝固位一体冠修复.随访6个月～2 a,记录螺丝固位的一体冠修复体的临床效果,采用SPSS17.0软件包对数据进行方差分析和x2检验.结果:经过6个月～2 a的随访观察,种植体存留率为99.61％,37例患者发生崩瓷,主要发生在3～4 mm组.在各组别中,烤瓷修复比金属(牙合)面烤瓷更容易发生崩瓷(P＜0.05);颌间距离越小,越容易发生崩瓷(P＜0.05).13件修复体发生螺丝松动,13例患者出现牙龈红肿,探诊出血.经牙周治疗及口腔卫生宣教后恢复良好.患者满意度较高.结论:种植体支持的螺丝固位一体冠修复设计可以解决磨牙区颌间距离不足的缺牙患者的修复难题,治疗效果良好.     

A comparison of the porcelain fracture resistance of screw-retained and cement-retained implant-supported metal-ceramic crowns

STATEMENT OF PROBLEM: The presence of a screw opening on the occlusal surface of implant-supported metal-ceramic crowns may decrease the porcelain fracture resistance and shorten the longevity of the crown. PURPOSE: The purpose of this study was to compare the porcelain fracture resistance between screw-retained and cement-retained implant-supported metal-ceramic crowns and to assess whether narrowing the occlusal table or offsetting the screw-access opening affects fracture resistance. MATERIAL AND METHODS: Forty standardized maxillary premolar metal copings were fabricated with a Pd-Ga alloy (Protocol) on an implant abutment. Copings were divided into 4 groups (n=10): Group 1 (Screw-retained; occlusal surface buccolingual width=5 mm), screw access opening placed in the center of the occlusal surface; Group 2 (Screw-retained; occlusal surface buccolingual width=5 mm), screw access opening positioned 1 mm offset from the center of the occlusal surface toward the buccal cusp; Group 3 (Cement-retained; occlusal surface buccolingual width=5 mm), copings were not altered; and Group 4 (Cement-retained; occlusal surface buccolingual width=4 mm), copings designed to have a reduced occlusal surface width. All castings were finished with aluminum oxide stones and airborne-particle abraded. Two layers of opaque and dentin porcelain were applied, respectively, on all specimens, which were then glazed. The crown specimens were positioned in a custom testing apparatus and vertically loaded on the middle of the occlusal surface with a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. Mean values of load at fracture (Kgf) were calculated in each group and compared with a 1-way analysis of variance and Tukey's Studentized test (alpha=.05). RESULTS: Mean values of loads required to fracture the crowns were as follow: Group 1: 95.01+/-46.6 Kgf; Group 2: 108.61+/-57.9 Kgf; Group 3: 390.94+/-151.3 Kgf; Group 4: 380.04+/-211.8 Kgf. Groups 1 and 2 required a significantly lower force to fracture the crowns compared with Groups 3 and 4 (P=.0001). Comparing Group 1 with 2 (P=.9) and Groups 3 with 4 (P=.6), no significant differences were noted. CONCLUSIONS: Screw-retained implant-supported metal-ceramic crowns demonstrated a significantly lower porcelain fracture resistance than cement-retained crowns. Placing the screw access opening 1 mm offset from the center of the occlusal surface did not result in lower fracture resistance. Cement-retained crowns with 4- or 5-mm buccolingual width of the occlusal surface showed similar porcelain fracture resistance.