Modern implant designs should allow for adequate primary stability but limit mechanical stress on buccal bone in order to prevent initial marginal bone loss. A dental implant characterized by a shift in core diameter and thread geometry was evaluated. Polyurethane foam was used as bone surrogate material and implant placement was performed measuring insertion torque and strain development on buccal bone using strain gauges as well as primary stability by using damping capacity assessments. An existing tapered bone-level implant was used as a control while the novel experimental implant described above (n = 10) was used in the test group. Statistical analysis was based on t-tests (α = 0.05). Both the maximum insertion torque (p = 0.0016) and maximum strain development in buccal bone (p = 0.1069) were greater in control implants as compared to the novel implant design. Moreover, in the control group, these were reached at a significantly later timepoint of the insertion process, i.e., when the implant was almost fully seated (maximum insertion torque p = 0.0001, maximum strain development p < 0.00001). The final insertion torque (p < 0.00001) and final strain development (p = 0.0137) were significantly lower in the novel implant design while the primary stability of both implant types did not differ significantly (p = 0.219). The novel implant design allowed for a greater undersizing of osteotomies while not mechanically overstressing buccal bone. Comparable primary stability was obtained from trabecular bone instead of compressing cortical bone as occurs in conventional, existing tapered implant designs.

Besides alveolar bone quality, the drilling protocol applied in conjunction with the design of an implant are the major determinants of primary implant stability. Surgical trauma and bone compression resulting from implant insertion may constitute one cause for marginal bone resorption. Inserting two current bone-level implant designs (Astra; Straumann; n = 5) in bovine ribs, primary stability, strain development on the buccal bone plate and histologic signs of bone damage were recorded. Besides comparing the implant designs (Welch t-tests), all measurement parameters were checked for potential correlations (Pearson product moment correlation coefficients) with the level of significance set at α = 0.05. Considerable numbers of crack formation and plastic deformation of bone were observed after implant insertion. Straumann implants showed slightly greater values for insertion torque (p = 0.772), strain development (p = 0.893) and implant stability (p = 0.642). Significantly greater bone to implant contact (cortical p = 0.014; trabecular p = 0.016) was observed in Straumann implants, while Astra implants caused a significantly greater number of microcracks in cortical bone (p = 0.020). In Straumann implants, insertion torque correlated with bone to implant contact in the cortical area (p = 0.029) and the number of macrocracks in trabecular bone correlated with bone to implant contact (p = 0.029). In Astra implants, insertion torque and bone to implant contact in the trabecular area correlated (p = 0.007) as well as the number of macrocracks in trabecular bone and implant stability (p = 0.016). Additionally, in the area of cortical bone, the number of macrocracks correlated with bone to implant contact (p = 0.019). Implant placement results in bone damage of varying magnitude, which is governed by the drill protocol, implant macrodesign and bone quality.

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.

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With increasing experience and in an attempt to shorten overall treatment times, implant placement in combination with tooth extractions and sinus lift procedures has become popular. In both cases, primary stability has to be achieved by either engaging apical and oral regions of trabecular bone or by engaging residual host bone beneath the sinus cavity. Extraction sites were formed by pressing a root analog into homogeneous low density polyurethane foam which was used as bone surrogate while a 3 mm thick sheet of medium density foam was used for mimicking a sinus lift situation. Two types (n = 10) of bone level implants with a conventional tapered design and a cervical back taper (NobelActive; control) and a novel design characterized by a shift in core diameter and thread geometry (AlfaGate; test) were placed in these models following conventional osteotomy preparation. Insertion torque was measured using a surgical motor and primary stability was determined by resonance frequency analysis. Statistical analysis was based on Welch two sample t tests with the level of significance set at α = 0.05. In sinuslifting, NobelActive implants required significantly higher insertion torques as compared to AlfaGate (p = 0.000) but did not achieve greater implant stability (p = 0.076). In extraction sites, AlfaGate implants showed both, significantly higher insertion torques (p = 0.004) and significantly greater implant stability (p = 0.000). The novel implant design allowed for greater primary stability when being placed in simulated extraction sockets and sinuslift situations. While in extraction sockets the position of condensing threads in combination with an increase in core diameter is beneficial, the deep cervical threads of the novel implant lead to superior performance in sinuslift situations.