Zahnärztliche Prothetik, Propädeutik und Werkstoffwissenschaften

Tactile sensitivity of natural teeth

2026-07-03T09:20:28Z

Tactile sensitivity of natural teeth Utz, Karl-Heinz In two experimental series, the tactile sensibility of natural antagonistic teeth was investigated.
In the first series, 109 subjects were tested using aluminium oxide particles of different sizes, uniformly distributed in yogurt. An absolute threshold value of 15 μm was determined. Male subjects detected slightly smaller foreign bodies than female subjects. Most participants were able to improve their threshold values through practice; however, they were not able to reduce them voluntarily.
In the second experimental series, tactile sensibility was assessed using copper foils of varying thicknesses. The median absolute tactile threshold values of 70 tested pairs of incisors, premolars, and molars amounted to 10 μm, whereas the corresponding value for canine tooth pairs was 20 μm.
Calculation of the 50% detection threshold yielded values of 29 μm for incisors, 63 μm for canines, and 17 μm for both premolars and molars. No sex-related differences were observed. The two experimental series assessed different aspects of tactile sensibility. No statistically significant associations were found between tactile performance and age, time of day, tooth alignment, the extent of sliding movement between centric relation and maximum intercuspal position, or the restorative status of the teeth.

Intraoperative Profiling of the Supracrestal Implant Complex Minimizes Peri-Implant Crestal Bone Remodeling

2025-10-24T13:16:35Z

Intraoperative Profiling of the Supracrestal Implant Complex Minimizes Peri-Implant Crestal Bone Remodeling Stoilov, Milan; Winterhoff, Joerg; Stoilov, Lea; Timoschenko, Anastasia; Stark, Helmut; Heuser, Florian; Marder, Michael; Kraus, Dominik; Enkling, Norbert (1) Background: Early-stage bone resorption following implant placement can significantly impact the long-term success of implants. This study evaluates whether a fully digitally planned implant position based on the E-point concept, along with guided profiling of the supracrestal complex, contributes to improved stability of peri-implant bone levels. (2) Methods: 29 implants were placed in 27 patients utilizing both immediate (Group 1; n = 19) and delayed placement (Group 2; n = 10) protocols. Implant position and emergence profile were preoperatively determined and consistently executed through guided surgery and CAD/CAM-fabricated restorations. Due to the subcrestal positioning of the implant, a corresponding bone profiler with a guide pin was used to shape the emergence profile and prevent the provisional restoration from impinging on the proximal bone. Provisional restorations were immediately placed to support the emergence profile. Bone level changes were documented radiographically over a two-year period. The first Bone-to-Implant Contact Level (∆ fBIC), change in highest approximal Bone Level (∆ haBL ), and formation of an emergence profile width (WEP) were measured. (3) Results: All implants and restorations survived after two years, no significant change in first Bone-to-Implant Contact Level (∆ fBIC = 0 ± 0.02 mm), no change in highest approximal Bone Level (∆ haBL ) of −0.23 mm ± 0.71 mm, and formation of an emergence profile width (WEP) averaging 0.18 ± 0.19 mm. (4) Conclusions: Despite the initial stress on the bone caused by bone profiling, guided implant placement and bone shaping, supported by an immediate provisional, have a positive effect on peri-implant bone stability.

Efficacy of Virtual Preparation Simulators Compared to Traditional Preparations on Phantom Heads

2025-08-01T13:04:16Z

Efficacy of Virtual Preparation Simulators Compared to Traditional Preparations on Phantom Heads Stoilov, Lea; Stephan, Fabian; Stark, Helmut; Enkling, Norbert; Kraus, Dominik; Stoilov, Milan Background: Virtual simulators are increasingly being introduced in dental education. This study investigates whether virtual simulators offer comparable or superior educational efficacy when compared to traditional phantom simulators. Materials and Methods: Participants were randomly allocated into groups: Virtual Preparation (SIM; n = 30) and Traditional Preparation (FRA; n = 30). Students were tasked with preparing tooth 36 for a full-cast crown during free practice for four days. Faculty staff provided feedback to both groups. Examinations were administered and graded by three examiners (preclinical and clinical consultants and a dental surgery consultant). Additionally, a survey was conducted to assess each training concept. Results: The FRA group achieved significantly better grades in the preparation exam evaluations by all three examiners, compared to the SIM group. Interrater reliability showed only moderate agreement, with the clinical examiner giving better grades than the other two. The questionnaire results indicate that while participants managed with the virtual system, they preferred the analog system for exams and patient preparation. Conclusion: Virtual simulators do not seem to be as good when it comes to practicing for a preparation exam or clinical preparation, especially for unexperienced students. However, they still appear to be useful as an additional tool for introducing students to the topic of preparation.

Influence of Cementation Mode and Ferrule Design on the Fatigue Resistance of Monolithic Zirconia Endocrowns

2025-06-25T10:16:25Z

Influence of Cementation Mode and Ferrule Design on the Fatigue Resistance of Monolithic Zirconia Endocrowns Stoilov, Milan; Boehmer, Tobias; Stoilov, Lea; Stark, Helmut; Marder, Michael; Enkling, Norbert; Kraus, Dominik Background: Classic endocrowns made of dental ceramics are considered a promising alternative to traditional post-endodontic restorations. The use of circular ferrules in endocrowns is a topic of controversial discussion. Therefore, the present study aims to evaluate the effect of ferrule design and cementation mode on the fatigue resistance of zirconia endocrowns.
Methods: Eighty human molars were divided into four groups (n = 20): NFC (no-ferrule, conventional cementation), NFA (no-ferrule, adhesive luting), FC (ferrule, conventional cementation) and FA (ferrule, adhesive luting). Both the classic and the modified endocrown preparation with a two-millimeter ferrule design were carried out. Endocrowns were fabricated from zirconia using the CEREC system. After thermocycling, specimens were loaded according to the step-stress test up to 1500 N.
Results: Failure rate was low; 88.8% of total specimens passed the step-stress test. Fractures were distributed between all groups; no significant differences in fatigue resistance were detected for preparation design and cementation mode.
Conclusions: Endocrowns appear to be a promising concept for endodontically treated molars. Ferrule and also cementation mode have only a minor influence on fatigue resistance of zirconia endocrowns. However, at very high forces, the marginal area of the ferrule represents a weak point.