Evaluation of different debridement strategies for implant-abutment connections: An in vitro study.

STATEMENT OF PROBLEM: Technical complications, including abutment fracture, are a clinical reality. After retrieving failed components, re-establishing a reliable implant-abutment connection is essential, but recommendations on how to clean the interface are lacking. PURPOSE: The purpose of this in vitro study was to evaluate different clinical debridement strategies for removing titanium powder from an implant-abutment interface with regard to their efficacy and associated risk of damaging the interface. MATERIAL AND METHODS: Specimens (n=5) were assembled from previously cut implant halves, which were then contaminated by placing titanium powder inside the implant-abutment connection. Activated rinsing, airflow, and an ultrasound scaler, as well as combinations thereof, were then used to clean the implant-abutment connections. Both parts of each specimen were rated under a light microscope with respect to contamination and damage. In addition, abutments were placed in intact implants (n=10), which had previously been contaminated and cleaned, to record torque curves and abutment stability. Statistical analysis of ratings was based on Kruskal-Wallis tests and the Nemenyi All Pairs test with single-step P value correction, while abutment stability and torque were analyzed using analysis of variance and Tukey HSD tests (α=.05). RESULTS: Erythritol as an abrasive medium led to significantly greater contamination than the scaler (P=.002), activated rinsing (P=.021), and airflow with sodium bicarbonate combined with either conventional (P=.002) or activated rinsing (P=.007). Greater damage was also observed with erythritol because of accumulations of the abrasive media, while scratches were seen after scaler application. Airflow using sodium bicarbonate in combination with activated rinsing showed the lowest level of damage (versus scaler P=.030). Using conventional (P=.010) or activated (P=.029) rinsing, airflow treatment led to a significant reduction in contamination. The scaler led to a significant decrease in abutment stability (P=.048), while activated rinsing and the combination of airflow and activated rinsing did not significantly affect abutment stability. Abutments placed in implants previously contaminated and cleaned required greater torque as compared with original implants (versus activated rinsing, P=.009). CONCLUSIONS: Activated rinsing constituted the best technique for cleaning implant-abutment connections. Cleaning efficiency can be enhanced with airflow using sodium bicarbonate as an abrasive medium.

Pilot study on the applicability of boron-doped diamond electrodes for tooth whitening.

OBJECTIVES: While various approaches are available for tooth whitening, the basic concept employs the use of peroxides in the form of gels, which are applied to tooth surfaces. Previous studies have shown that reactive oxygen species acting as potent disinfectants can be produced using boron-doped diamond (BDD) electrodes for the electrolysis of water. With these electrodes being applicable, for example, for endodontic treatment, it was the goal of this pilot study to use such electrodes for tooth whitening. MATERIAL AND METHODS: Two groups (n = 10) of intact clinical crowns were obtained by horizontally cutting off roots of extracted human teeth. The crowns were either bleached by applying a commercially available agent based on 40% hydrogen peroxide or were immersed in saline undergoing electrolysis with BDD electrodes. Whitening of specimens was judged on standardized photographs by examiners with three different levels of experience. Statistical analysis was based on Gwet's AC2 coefficient with quadratic weights, Shapiro-Wilk tests, and two-way analysis of variance of aligned rank transformed data (level of significance set at α = .05). RESULTS: Levels of reliability ranging from fair to substantial were recorded for single persons while the level of reliability ranged between fair and moderate for groups of raters. The level of experience had no significant effect on the ratings (p = .2500). The bleaching method had a significant effect on ratings (p = .0005) with BDD electrodes showing less effect. CONCLUSIONS: Bleaching by applying BDD electrodes was possible, but was not as effective as the use of commercially available in-office whitening gel. A potential explanation may be seen in different concentrations of reactive oxygen species.

Use of a dentin bonding agent for the fixation of strain gauges on bone.

Capturing deformation of bone using strain gauges is still a common approach in biomechanics. So far, the bone surfaces had to be sanded and cleaned using various solvents prior to attaching the sensors using cyanoacrylate. This work proposes a novel approach employing common bonding procedures to enamel and dentin as used in restorative dentistry. Bovine ribs were obtained and osteotomies were created following clinical protocols for dental implant insertion. A unidirectional strain gauge was attached to the outer surface of the bone specimens using the steps of acid etching with phosphoric acid, application of a three-bottle dentin adhesive and light curing. Emerging strains were then captured during implant insertion as well as during static loading of the implants in a universal testing machine. The method described here allowed for the reliable fixation of strain gauges on unaltered bone surfaces. Both, compressive and tensile strains emerging in the surrounding of the dental implants could be captured.