An in vitro evaluation of 2 methods for retrieving fractured abutment screw fragments from the intaglio of 4 different implant systems.

STATEMENT OF PROBLEM: When an abutment screw fractures, there is no standardized technique for retrieving it from the intaglio of the dental implant. PURPOSE: The purpose of this in vitro study was to assess the relative efficacy of a commercially available screw fragment retrieval kit with a range of standard dental instruments in regard to success and retrieval time. In addition, the effects of other variables on the success rate of screw fragment retrieval and the retrieval time required were also investigated. Finally, the integrity of the intaglio screw channel of the dental implant was also assessed following retrieval. MATERIAL AND METHODS: The abutment screws from 4 dental implant systems: Osseotite Certain, Ø4.1 mm (Zimmer Biomet); Osseotite External hexagonal connection micromini, Ø3.25 mm (Zimmer Biomet); Standard Plus Tissue Level, Ø4.8 mm (Institut Straumann AG); and Brånemark Mark III TiUnite, Ø4.1 mm (Nobel Biocare) had notches placed between the first and second coronal threads before being placed in their respective abutments, positioned in the dental implants (n=128), and tightened until the screws fractured. The dental implant specimens were placed in maxillary and mandibular casts at the lateral incisor and first molar sites on both sides. The casts were placed in mannequin heads on a dental chair and assigned to 2 experienced and 2 inexperienced operators who used 2 different retrieval kits to retrieve the screw fragments. Chisquared tests were used to determine the association between the success rate of screw fragment retrieval and the other factors recorded (α=.05), and a binary logistic regression was used to determine the association between the retrieval event and all of the independent variables. Regression models were developed to determine the factors effecting retrieval time. RESULTS: An overall success rate of 88.3% was achieved for screw fragment retrieval. No statistically significant difference (P=1) was found in the relative efficacy of the retrieval kits. Univariate analysis identified a statistically significant association (P<.01) in the success of abutment screw fragment retrieval between the Osseotite Certain and the Osseotite External hexagonal connection micromini implant systems. Gamma regression analysis identified significant differences between the time taken to retrieve the screw fragments and the type of dental implant (P<.001), (P<.01). The time taken to retrieve screw fragments in the maxillary arch was significantly longer than for the mandibular arch (P<.05). CONCLUSIONS: The commercially available screw fragment retrieval kit and the standard dental instruments were equally effective in retrieving the screw fragments. Less time was required to retrieve screw fragments in the mandibular arch than the maxillary arch. The level of experience of the operator had no effect on the ability to successfully retrieve fractured abutment screws.

The effect of a decontamination protocol on contaminated titanium dental implant surfaces with different surface topography in edentulous patients.

Objectives: To investigate if it is possible to achieve complete decontamination of dental implant surfaces with different surface characteristics.Materials and methods: Twelve implant pieces with an Osseotite® surface and 12 implant pieces with a Ti-Unite® surface were attached on to the complete lower dentures of six patients and were allowed to accumulate plaque for 30 days. When retrieved, the implant decontamination protocol used, involved both mechanical (PeriBrush™) and chemical (3% H2O2) decontamination. The number of colony forming units per millilitre was determined and the dominant micro-organisms in selected samples was identified by 16s rRNA gene amplicon sequencing. The effect of the titanium brush on the implant surface was examined by SEM.Results: Complete decontamination was achieved in five out of 24 implants (four Osseotite® and one Ti-Unite®). The mean CFU/ml detected after decontamination were 464.48 for Osseotite® and 729.09 for Ti-Unite® implants. On the surface of the implants in which complete decontamination was not achieved, all of the predominant bacteria identified were streptococci except for one which was identified as micrococcus. SEM images revealed that the surface features of the decontaminated implants were not significantly altered.Conclusions: Mechanical decontamination using a titanium brush supplemented with chemical treatment for one minute (3% H2O2) can achieve complete decontamination of implant surfaces in edentulous patients.

Immediate loading of occluding definitive partial fixed prostheses vs non-occluding provisional restorations - 3-year post-loading results from a pragmatic multicentre randomised controlled trial.

PURPOSE: To compare the clinical outcome of dental implants restored with definitive occluding partial fixed prostheses within 1 week after implant placement with immediate non-occluding provisional restorations to be replaced by definitive prostheses after 4 months. MATERIALS AND METHODS: Forty partially edentulous patients treated with one to three dental implants, at least 8.5 mm long and 4.0 mm wide, inserted with a torque of at least 35 Ncm, were randomised in two groups of 20 patients each, to be immediately loaded with partial fixed prostheses. Patients in one group received one definitive screw-retained, metal-ceramic prosthesis in occlusion within 1 week after placement. Patients in the other group received one non-occluding provisional acrylic reinforced prosthesis within 24 h of implant placement. Provisional prostheses were replaced by definitive ones after 4 months. The follow-up for all patients was 3 years post-loading. Outcome measures were prosthesis and implant failures, any complications, peri-implant marginal bone level changes, aesthetic evaluation by a dental practitioner, patient satisfaction, chair time and number of visits at the dental office from implant placement to delivery of definitive restorations. RESULTS: Three patients dropped out, one from the non-occlusal group and two from the occlusal group. Two immediately occlusally loaded implants with their related definitive prostheses failed early (difference in proportions = 0.10; 95% CI = -0.03 to 0.23; P = 0.488). Five patients from the occlusally loaded group were affected by six complications vs three patients (three complications) in the non-occlusally loaded group. The difference in proportions was not statistically significant (difference in proportions = 0.08; 95% CI = -0.17 to 0.34; P = 0.697). Three years after loading, patients subjected to occlusal loading lost an average of 1.13 mm of peri-implant bone vs 1.03 mm of patients restored with non-occluding definitive partial fixed prostheses. There were no statistically significant differences for marginal bone level changes between the two groups (mean difference = 0.10 mm; 95% CI -0.62 to 0.82; P = 0.779). No significant were the differences for pink aesthetic scores (7.09 vs 6.90; P = 0.873); for aesthetics evaluated by patients (Mann-Whitney U test P = 0.799) and function satisfaction (Mann-Whitney U test P = 0.578). Significantly less chair time (mean difference -38.00; 95% CI -58.96 to -17.04; P = 0.001) and number of visits (mean difference -2.15; 95% CI -2.77 to -1.53; P < 0.001) were required for the immediate definitive prosthesis group. CONCLUSIONS: This study did not provide a conclusive answer, but suggests that immediate occlusal loading by manufacturing immediate definitive partial fixed prostheses decreases chair time and number of visits.

Immediate occluding definitive partial fixed prosthesis versus non-occluding provisional restorations - 4-month post-loading results from a pragmatic multicenter randomised controlled trial.

PURPOSE: To compare the clinical outcome of dental implants restored with definitive occluding partial fixed prostheses within 1 week, after implant placement with immediate non-occluding provisional restorations, which were to be replaced by definitive prostheses after 4 months. MATERIALS AND METHODS: Fifty partially edentulous patients treated with one to three dental implants, at least 8.5 mm long and 4.0 mm wide inserted with a torque of at least 35 Ncm, were randomised in two groups of 25 patients each, to be immediately loaded with partial fixed prostheses. Patients of one group received one definitive screw-retained metal-ceramic prosthesis in occlusion within 1 week after placement. Patients of the other group received one non-occluding provisional acrylic reinforced prosthesis within 24 h after implant placement. Provisional prostheses were replaced after 4 months by definitive ones. The follow-up for all patients was 4-months post-loading. Outcome measures were prosthesis and implant failures, any complications, peri-implant marginal bone level changes, aesthetic evaluation by a clinician, patient satisfaction, chair time and number of visits at the dental office from implant placement to delivery of definitive restorations. RESULTS: No patient dropped out. Two immediately occlusally loaded implants with their related definitive prostheses (8%) failed early (difference in proportions = 0.08; 95% CI: -0.03 to 0.19; P = 0.490). Four complications occurred in the occlusal group versus one in the non-occlusal group; (difference in proportions = 0.12; 95% CI: -0.04 to 0.28; P = 0.349). Four months after loading, patients subjected to non-occlusal loading lost an average of 0.72 mm of peri-implant bone versus 0.99 mm of patients restored with occluding definitive partial fixed prostheses. There were no statistically significant differences for marginal bone level changes between the two groups (mean difference = -0.27 mm; 95% CI: -0.84 to 0.30; P = 0.349). The differences for aesthetic scores showed no statistical significance (8.26 versus 7.58; P = 0.445); the same was seen for aesthetics evaluated by patients (Mann-Whitney U test: P = 0.618). Patients in the non-occlusal group were significantly more satisfied with the function of their implant-supported prostheses (Mann-Whitney U test: P = 0.039). Significantly less chair time (mean difference = -28.4 min; 95% CI: -48.82 to -7.99; P = 0.007) and the number of visits (mean difference = -1.88; 95% CI: -2.43 to -1.33; P < 0.001) were required for the immediate definitive prosthesis group. CONCLUSION: This study did not provide a conclusive answer but may suggest that provisional prostheses non-occlusally immediately loaded may increase patient functional satisfaction, chair time and the number of visits, with respect to definitive prostheses immediately loaded in functional occlusion.