Identification of risk factors for fracture of veneering materials and screw loosening of implant-supported fixed partial dentures in partially edentulous cases

Screw-retained ceramic-veneered/monolithic zirconia partial implant-supported fixed dental prostheses: A 5 to 10-year retrospective study on survival and complications

PURPOSE

To assess the clinical performance of screw-retained, ceramic-veneered, monolithic zirconia partial implant-supported fixed dental prostheses (ISFDP) over 5-10 years and to evaluate implant- and prosthesis-related factors influencing treatment failure and complications.

MATERIALS AND METHODS

Partially edentulous patients treated with screw-retained all-ceramic ISFDPs with 2-4 prosthetic units with a documented follow-up of ≥5 years after implant loading were included in this retrospective study. The outcomes analyzed included implant/prosthesis failure and biological/technical complications. Possible risk factors were identified using the mixed effects Cox regression analysis.

RESULTS

A screened sample of 171 participants with 208 prostheses (95% of the restorations were splinted crowns without a pontic) supported by 451 dental implants were enrolled in this study. The mean follow-up duration after prosthesis delivery was 82.4 ±17.2 months. By the end of the follow-up period, 431 (95.57%) of the 451 implants remained functional at the implant level. At the prosthesis level, 185 (88.94%) of the 208 partial ISFDPs remained functional. Biological complications were observed in 67 implants (14.86%), and technical complications were observed in 62 ISFDPs (29.81%). Analysis revealed only emergence profiles (over-contoured) as a significant risk factor for implant failure (P<0.001) and biological complications (P<0.001). Full-coverage ceramic-veneered zirconia prostheses had a significantly greater chance of chipping (P<0.001) compared with buccal-ceramic-veneered or monolithic zirconia prostheses.

CONCLUSIONS

Screw-retained ceramic-veneered, monolithic partial ISFDPs have a favorable long-term survival rate. Over-contoured emergence profile is a significant risk factor associated with implant failure and biological complications. Buccal-ceramic-veneered and monolithic zirconia partial ISFDPs lower the initial prevalence of chipping compared with a full-coverage veneered design.

Survival and complication rates of tooth-implant versus freestanding implant supporting fixed partial prosthesis: a systematic review and meta-analysis

PURPOSE

This systematic review was performed to compare tooth, implant and prosthesis failures and biological and technical complications in toothimplant vs freestanding implant supported fixed partial prostheses, in order to evaluate the effectiveness and predictability in combining teeth and implants in the same fixed partial prosthesis.

STUDY SELECTION

A comprehensive and systematic literature research was conducted, according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, to identify human trials, with a minimum sample size of 10 patients, comparing tooth-implant to freestanding implant supported fixed partial prostheses. Four groups of meta-analyses were performed based on the patients treated with toothimplant vs freestanding implant-supported fixed partial prostheses: abutment failures, biological and mechanical complications, prosthesis failures, and prosthetic (technical) complications.

RESULTS

The search yielded 749 records, after removal of duplicates. Based on the title assessment, the abstracts reading and the full-texts evaluation, 8 articles, published between 1999 and 2013, fulfilled the inclusion criteria and were included in the meta-analysis. The studies included were: 4 controlled clinical trials, 2 prospective and 2 retrospective cohort studies. The meta-analysis revealed no significant difference between tooth-implant and implant-implant supported fixed in the number of abutment (implant or tooth) failures, biological complications, prosthesis lost, and prosthetic complications.

CONCLUSIONS

Within the limitations of the present systematic review, although the freestanding implant supported fixed partial prosthesis remains the first choice, joining teeth and implants to support fixed prosthesis in partially edentulous patients becomes a valid alternative with an acceptable success rate.

Mechanical complications of implant-supported complete-arch restorations and impact on patient quality of life: A retrospective cohort study

STATEMENT OF PROBLEM

Mechanical complications (for example, fractures) in implant-supported complete-arch restorations may affect the social and professional activities of the patient. However, most studies seem to overlook patient perceptions and generally do not assess the changes in the quality of life (QoL) of patients who experience these complications.

PURPOSE

The purpose of this retrospective cohort study was to assess the influence of technical or mechanical complications of complete-arch implant-supported prostheses on patient perception and QoL by using the Oral Health Impact Profile (OHIP)-14.

MATERIAL AND METHODS

A retrospective cohort study was formed of patients treated consecutively at a private clinic with immediately loaded complete-arch prostheses supported by a minimum of 4 implants (Replace Tapered; Nobel Biocare AB) and Multi-Unit conical abutments (Multi-Unit abutments; Nobel Biocare AB). OHIP-14 and questions regarding self-reported satisfaction were used to evaluate the influence of mechanical complications on QoL.

RESULTS

Fifty-six participants (26 men and 30 women) with a mean age of 64 ±11.1 years, and 72 restored arches were included. The mean ±standard deviation follow-up time was 52 ±26 months. The prosthetic success rate was 38.8%, and the survival rate was 100% (no failure was registered). The most common complications were abutment screw loosening (43%), chipping or fracture of the veneering material (25%), and screw loosening (21%). The OHIP-14 scores were close to zero, without differences between participants with or without mechanical complications. Overall, the participants reported that the prostheses allowed good oral hygiene (94.6%) and met their expectations (89%) and that they would repeat the treatment (87.5%) and would recommend it to others (93%).

CONCLUSIONS

Minor mechanical complications such as screw loosening and chipping or fracture of the veneering material were frequent events but had no impact on the satisfaction and QoL of patients with immediately loaded complete-arch implant-supported prostheses.

Analysis and management of implant-prosthetic complications: Description of a diagnostic and therapeutic algorithm with a clinical case

PATIENT

A 65-year-old non-smoker man with stabilized chronic periodontitis and in good general health conditions presented to our observation. The patient reported crown mobility, gingival inflammation and localized pain, corresponding to the mandibular right first molar rehabilitated with a cement-retained implant crown. This clinical situation suspected a fracture of an implant-prosthetic component. Through the described diagnostic algorithm, an abutment hexagon fracture was revealed. Thus, a minimally invasive treatment was carried out in order to use the residual implant-prosthetic components for a new implant-prosthetic rehabilitation.

DISCUSSION

Fractures of implant-prosthetic components are clinical occurrences that may result in irreversible failures. The main causes of a possible fracture are dependent on biomechanical considerations and production processes of implant-prosthetic components. The respect of the rigorous planning and the employment of the implant-prosthetic devices of the same manufacturer are recommended.

CONCLUSIONS

Specific employments and protocols have to be offered in order to manage the fractures of implant-prosthetic components. This work showed that through the described diagnostic and therapeutic algorithm, the clinician can be guided towards a proper diagnosis and a correct management of the cases where a fracture of implant-prosthetic components may occur.

Influence of Abutment Surface Treatments on Screw Loosening of Morse Taper Implants

PURPOSE

To evaluate the effect of blasting and bonding on abutment surface to prevent screw loosening in Morse taper connections.

MATERIAL AND METHODS

Twenty-eight Morse taper connection implants were divided into 4 groups: no treatment (G1), blasting (G2), bonding (G3), and blasting + bonding (G4). In groups G2 and G4, the abutments were blasted with aluminum oxide granules; in groups G3 and G4, the conical abutment region was covered with a thin layer of bond thread lock agent. In all implants, the abutment-implant joint was tightened at a torque of 35 Ncm. The specimens were submitted to the mechanical cycling, under an oblique load for 1.0 × 10 cycles. The torque was measured with a digital torque meter. Data were analyzed by the t test, one-way analysis of variance, and Tukey tests (95%).

RESULTS

The loosening strength was significantly higher in group G4 (35.83 ± 3.02 Ncm). There was no significant difference among groups G1 (25.86 ± 1.96 Ncm), G2 (25.86 ± 3.29 Ncm), and G3 (26.14 ± 2.12 Ncm).

CONCLUSION

The association of blasting and bonding on abutment surface can be used to prevent screw loosening in Morse taper implants.