The Root Membrane Technique: A Retrospective Clinical Study With Up to 10 Years of Follow-Up.

PURPOSE: Immediate implant placement in conjunction with intentional root retention is a recently introduced technique, but the majority of existing documentation is limited to short-term reports with low level of evidence. Hence, the aim of this study was to document the long-term clinical and radiographic results of the root membrane technique. METHODS: This retrospective study reports on clinical results of the root membrane technique for periodontal ligament-mediated immediate implant placement with up to 10 years of follow-up from 3 private dental practices. Anterior implants placed with immediate loading from January 2006 to December 2016 were assessed. Kaplan-Meier estimators were computed for reporting of implant success and survival. RESULTS: A sample of 182 patients (82 men and 100 women, age range: 18-83 years) received 250 immediate implants (230 maxilla, 20 mandible) after the root membrane concept and followed-up for a mean of 49.94 months (±32.5). Overall, 5 implant failures were recorded for a 10-year cumulative patient-level implant survival rate of 96.5%. Considering mechanical and biological complications, the 10-year cumulative implant success rate was 87.9%. CONCLUSIONS: Within the limits of the retrospective design, the root membrane technique showed long-term success rates comparable to those of conventional immediate implants.

Aesthetic and radiographic outcomes using the root membrane technique in immediate adjacent implant placement: A retrospective clinical study with a 5- to 9-year follow-up.

PURPOSE: The root membrane technique was designed to preserve the buccal portion of the root in situ, preventing postextraction bundle bone loss and overlying soft tissue recession. Nevertheless, maintenance of the aesthetic gingival architecture around two or multiple adjacent implants, particularly in the anterior maxilla, remains a challenge, notably regarding the gingival contour and the interimplant papillae. The present study aimed to evaluate the clinical, aesthetic and radiographic outcomes for immediate adjacent implants placed using the root membrane technique in the anterior maxilla in a sample with a 5- to 9-year follow-up. MATERIALS AND METHODS: A retrospective clinical study was designed using the medical records of two private dental practices. A total of 40 patients who were treated using the root membrane technique for at least two adjacent implants and single-crown restorations between January 2010 and February 2019 were selected (100 implants). The clinical and radiographic data were analysed to assess implant survival/success, marginal bone loss and the pink aesthetic score. RESULTS: The cumulative survival rate after a mean follow-up period of 81.5 ± 30.5 months was 99.0% (implant-based) and 97.5% (patient-based), respectively. Between 1 and 5 years (n = 99), the mean marginal bone loss changed from 0.39 ± 0.07 mm to 0.36 ± 0.07 mm and subsequently to 0.37 ± 0.07 mm at the 7-year follow-up (n = 71) and 0.33 ± 0.07 mm at the 9-year follow-up (n = 14). The improvement from 1 year was significant at all the follow-up time points (P = 0.000). The mean global pink aesthetic score increased from baseline (11.33 ± 1.03) to 3 months after placement of the final restoration (11.73 ± 0.95) and the final observation (12.01 ± 0.87). This was a significant increase (P = 0.000 baseline to 3 months, 3 months to final observation and baseline to final observation). CONCLUSIONS: In this non-controlled retrospective study, adjacent implants placed using the root membrane technique achieved a satisfactory survival and success rate. The variation in marginal bone loss showed a significant positive trend from 1 year to 5 and 7 years. The overall pink aesthetic scores improved significantly between sequential observation periods. CONFLICT-OF-INTEREST STATEMENT: Dr Leitão-Almeida receives personal fees (for sponsored lectures) and non-financial support from MegaGen (Daegu, South Korea) outside of the submitted work; the other authors declare no conflicts of interests relating to this study.

Clinical Outcomes of Monolithic Zirconia Crowns with CAD/CAM Technology. A 1-Year Follow-Up Prospective Clinical Study of 65 Patients.

Aim/Purpose: The primary aim of this study was to examine the clinical performance of posterior monolithic single crowns in terms of failure or complications and the secondary aim was to assess the quality of these restorations according to the United States Public Health Service (USPHS) criteria. Methods: Ιn a private dental clinic, 65 patients with need of posterior crowns were restored with monolithic zirconia crowns. All the restorations were evaluated 6 and 12 months after their cementation. The modified United States Public Health Service (USPHS) criteria and periodontal parameters were applied for the clinical evaluation of the crowns. Restorations with Alpha or Bravo rating were considered a success. Results: Descriptive statistics and nonparametric tests were used for statistical analysis. Sixty-five patients (mean age: 49.52) were restored with 65 monolithic zirconia crowns. No fracture of the restorations was recorded. The overall success rate was 98.5%. The clinical quality of all crowns was acceptable except for the marginal discoloration of one crown at the 6- and 12-month follow-up examination. Conclusions: In this study, no fracture of single-tooth monolithic crowns occurred and the success rate was high. Monolithic zirconia restorations fabricated is a viable option for the restoration of single posterior teeth.

The Root Membrane Technique: Human Histologic Evidence after Five Years of Function.

BACKGROUND: The "root membrane" (RM) is a technique that has become popular among implantologists for placement of immediate implants in the anterior maxilla. PURPOSE: To present histologic evidence of an immediate implant placed in the human anterior maxilla, according to the RM technique, and retrieved after five years. METHODS: A fixture, along with the surrounding tissues, was retrieved from the anterior maxilla of a 68-year-old patient, who had been treated five years earlier with immediate implant placement and RM technique. The specimen was processed for histologic/histomorphometric evaluation. RESULTS: The buccal bone plate was maintained without any resorption; a healthy periodontal ligament was evidenced. The implant showed osseointegration, with a high percentage of bone-to-implant contact (BIC = 76.2%). With regard to the space between the RM and the implant, the apical and medial thirds were filled with compact, mature bone; the coronal third was colonized by noninfiltrated connective tissue. CONCLUSIONS: The RM technique appears to be effective in preventing bone resorption of the buccal bone plate of the human anterior maxilla, five years after the placement of an immediate implant.

A Step-by-Step Description of PDL-Mediated Ridge Preservation for Immediate Implant Rehabilitation in the Esthetic Region.

The aim of this study was to present in detail the clinical steps of the root-membrane technique. This technique combines the benefits of conventional root submergence via intentional maintenance of a root fragment for ridge preservation with those of immediate implant placement for functional rehabilitation of the treated site. A case study of a tooth diagnosed with a horizontal root fracture is used to illustrate this technique step by step. The clinical application of the root-membrane technique not only allowed for immediate placement in a site with compromised buccal plate but also facilitated excellent clinical stability of soft tissue contours during the 3 years of follow-up.

Reliability and failure modes of two Y-TZP abutment designs.

Fracture strength and accelerated fatigue reliability of two zirconia abutment systems were tested. Thirty-six implants with a Morse taper (MT; n = 18) or cone (C; n = 18) design were restored with metallic crowns. Loads were applied as single load to failure (SLF) or mouth-motion cycles using a step-stress accelerated life testing (SALT) method. SLF mean values were 690 ± 430 N and 209 ± 25 for MT and C groups, respectively. In terms of the SALT results, 8 specimens survived (50,000 cycles) and 7 failed (maximum load 400 N) in the MT group; whereas for the C group all abutments failed before the maximum number of cycles. Failure mode was fracture of the Y-TZP abutments for both groups. Higher reliability for a mission of 50,000 cycles at 175 N for MT versus C designs was determined, and significant differences in fracture modes were observed.

Immediate implant placement in the esthetic zone utilizing the "root-membrane" technique: clinical results up to 5 years postloading.

PURPOSE: To clinically evaluate immediate implant placement with simultaneous intentional retention of the buccal aspect of the root and to report longitudinal data on survival of implants placed with the use of this novel technique. MATERIALS AND METHODS: A retrospective case series of implants placed with the root-membrane technique in the maxillary anterior region of adult patients was conducted. Clinical and radiographic analysis was performed to assess implant success and to evaluate the survival of the retained root fragment based on predetermined criteria. A Kaplan-Meier method analysis was used to estimate the 5-year success rate of implants placed with this technique. RESULTS: Data from 46 patients (median follow-up time, 40 months; range, 24 to 60 months) were evaluated. Each patient contributed one implant site in this study. All implants successfully maintained osseointegration at the end of the follow-up period for a 100% cumulative survival rate, based on clinical and radiographic criteria. Radiographic examination revealed good crestal bone stability with mean crestal bone loss on the mesial and distal aspects of the implants estimated to be 0.18 ± 0.09 mm and 0.21 ± 0.09 mm, respectively. The only complication noted in this patient cohort was apical root resorption of a single retained root fragment that did not interfere with the osseointegration of the implant. CONCLUSION: The intentional retention of the buccal aspect of the root with its periodontal apparatus during immediate implant placement can lead to predictable and sustainable osseointegration of implants placed in the maxillary anterior region of healthy adults.

Reliability and fatigue damage modes of zirconia and titanium abutments.

The fracture strength and accelerated fatigue reliability of metal and zirconia abutment systems were tested. Implants with either titanium (Ti, n = 9) or zirconia abutments(Zr, n = 18) were restored with metal crowns. Loads were applied as either a monotonic load to failure or mouth-motion cycles using a step-stress accelerated life testing method. At failure, monotonic loads were 1,475 +/- 625 N for Ti and 690 +/- 430 N for Zr. In step-stress testing, the Ti group was truncated at 70,000 cycles and a 900-N load with no fractures. In the Zr group, eight specimens survived and seven failed, with a maximum load of 400 N. Strength and reliability were significantly higher for the Ti abutments compared to the Zr. Int J Prosthodont 2010;23:56-59.

In vitro evaluation of a mechanical testing chewing simulator.

OBJECTIVES: In this in vitro study, the force-profile of a commonly used chewing simulator (Williytec, Munich, Germany) utilizing fixed weights for loading was evaluated. METHODS: Using piezoelectric force sensors the maximum and mean values of the applied forces were recorded in three different load configurations in order to determine the repetition accuracy in one test chamber. The variation in resulting forces of the eight test loading-chambers when using three different loads and descending speeds was explored. RESULTS: The simulator showed high load repetition accuracy between the different cycle rates. Significant differences (up to 38.2+/-0.4N) were observed between the different specimen chambers. In addition, the recorded loads were generally both higher (up to 137.5+/-0.4N) and lower than the nominal loads defined by the static weights. The extent of load variation at contact was highly dependent on the descending cross-speed and selected weight. Finally there were also ringing in the load profiles attributed to vibrations of the mechanical setup. SIGNIFICANCE: Studies using weight-controlled chewing simulators should consider these effects when reporting results. In addition, calibrations should be performed to check uniformity of tests conditions for each test chamber.