Study of the use in autonomy of intraoral scanning systems to optimise dental students' performances in fixed prosthodontics practical learning in second year.

AIM: The purpose of this study was to evaluate if the use of intraoral scanner analysis could help students to optimise their performance and their self-assessment abilities in prosthetic preparation without the teacher's assistance in the preclinical course. MATERIALS AND METHODS: Ninety-five second-year dental students were randomly divided into three groups: Control group (C), CeRec group (CR) and PrepCheck group (PC). Group C only use silicon keys to control the preparation thickness. The students in Group CR analysed their work with Cerec™ software. The Group PC use a pedagogic software (PrepCheck™) which allowed comparison with the "master" preparation. They used control tools preparations for three consecutive training sessions. Then a final assessment session without control tool to evaluate their performance was organised. All preparations were objectively evaluated thanks to stl. analysis software (Geomagic® Control X). Each preparation was compared with the master preparation by defining tolerance ranges. An objective overall score out of 20 was assigned to each preparation according to their degree of correspondence. In addition, a questionnaire was performed to analyse the students' perceptions regarding the use of intraoral camera. RESULTS: During the assessment session, no significant difference was revealed between the different groups with respect to the students' performance. The comparative analysis between the self-assessment scores and the objective scores using Geomagic® software showed that digital control tools did not help the student to improve their self-assessment abilities without the teacher's assistance. CONCLUSIONS: The intraoral cameras and specific pedagogic software in autonomy could not improve students' performance for teeth preparation and self-assessment abilities in second year. These digital tools facilitate objective feedback on preparation defects, but constructive criticism needs human reflection. The teacher's opinions and advice remain essential to develop their students' performance and self-assessment skills. The use of digital tools must be integrated in dentistry course to develop the interpret of the results and optimise feedback.

Effect of a Procedural Video on the Practical Fixed Prosthodontic Performance and Stress among Preclinical Dental Students.

OBJECTIVE: The purpose of this article was to analyze the effect of an instructional video on practical tutorial and to ascertain whether an instructional video improves students' performance on practical performance and reduces the stress associated with learning. MATERIALS AND METHODS: A randomized controlled trial was conducted on a group of 78 first-year students. A pretest was conducted by administering questionnaires to evaluate the interest in the use of videos as well as the level of stress. Students were randomly assigned into two groups: control and test. Students assigned to the control group received conventional teaching, while the experimental group received both conventional teaching and watched a video. Thereafter, a satisfaction questionnaire was distributed to each of the groups, and they were awarded a grade. RESULTS: A total of 98.7% of students wished to learn fixed prosthodontics through instructional videos, as they believed that the videos could reduce their worry and stress levels. At the end of the first tutorial, the total grade was significantly lower for the test group (p = 0.003). However, the subjective value of stress was significantly lower in the test group (p = 0.0007) as well as the subjective value of tutorial difficulty (p = 0.0004). Students felt that they better understood the objectives of the tutorial "thanks to the video" (p = 0.0001). CONCLUSION: This study did not reveal any improvement in terms of performance when an instructional video was used for tutorials in comparison with the conventional teaching method. However, the results show a reduction in the level of stress.

Using the "One Shot" Concept for Immediate Loading Implant Protocol in Edentulous Patient Rehabilitation with a Fixed Prosthesis: A 6-Year Follow-Up.

Immediate-loaded implants with a fixed prosthesis are a viable option for the restoration of edentulous ridges. Several procedures now allow for the fabrication of immediate-loading provisional and definitive prostheses. However, this complex treatment is not accessible to all patients with budget restrictions. By using a unique master model with a single titanium framework prosthesis can simplify and shorten the treatment, as well as reduce costs. After surgical placement of implant fixtures, an interim prosthesis was fabricated using a laser-welded definitive titanium framework. The prosthesis was fitted intraorally following the immediate loading protocols. The master cast model used to fabricate interim prosthesis was conserved and subsequently used in modifying the final prosthesis. After the healing process and complete soft tissue stability, an impression was made to register the clearance between the gingiva and resin. The light silicone material was directly injected under the prosthesis screwed in the mouth. In the master cast model, the stone was eliminated between the implants and a new plaster was poured to modify the crest profile with the posthealing new shape. With this modified model, it is possible to rehabilitate the denture to the new gingival anatomy in 3 to 4 hours and, if necessary, the tooth rearrangement. This "one shot" concept combines the single definitive titanium welded framework and limited laboratory work with a unique master model thereby decreasing the cost and the time of treatment.

Dental biomaterials for chairside CAD/CAM: State of the art.

The wide use of chairside CAD/CAM restorations has increased the diversity of the restorative material. For the practitioner, the selection of the appropriate material is difficult amongst the variety offered by the market. Information on the characteristics of the products can be difficult to assess due to the lack of up-to-date classification and the lack of reliability of manufacturer's advertising. The purpose of this article is to structure the data on restorative materials provided by various sources in order for the practitioner to choose the product most suited to the clinical situation. The objective is to classify chairside CAD/CAM materials and to define their characteristics and indications.

Chairside Computer-Aided Design/Computer-Aided Manufacture All-Ceramic Crown and Endocrown Restorations: A 7-Year Survival Rate Study.

PURPOSE: The objective of the present study was to analyze the clinical outcomes of 447 monoblock ceramic chairside computer-aided design/computer-aided manufacture (CAD/CAM) reconstructions over a 7-year functional period. Of these reconstructions, 212 were peripheral crowns and 235 were endocrowns. MATERIALS AND METHODS: The restorations were placed between 2003 and 2008 in a total of 323 patients. They were created using a chairside CAD/CAM method and the same materials in all cases. All of the crowns were manufactured and glued during the same clinical session by the same practitioner. Data were descriptively analyzed and survival probabilities were calculated using Kaplan-Meier statistics. RESULTS: Of the 447 restorations, only 6 failures occurred, resulting in a success rate of 98.66%. All of the failures were the result of a partial ceramic fracture. Of the six ceramic fractures, five appeared on peripheral crowns and one on an endocrown. All fractures appeared in the first 24 months, including two in the first month. Log-rank test comparing incidence rates between crowns and endocrowns showed no significant differences (P = .08). CONCLUSION: This survival rate study reinforced the use of CAD/CAM full ceramic crowns and endocrowns on molars, showing a much more favorable survival rate for endocrowns.

Glass Ceramic CAD/CAM crowns and severely altered posterior teeth: a three levels study.

For many practitioners, longevity of full glass ceramic crowns in the posterior area, molars and premolars, remains a real challenge. The purpose of this article is to identify and evaluate the parameters that can significantly influence their resistance when preparing a tooth. The analysis proposed in this article relies on interrelated studies conducted at three levels: in vitro (mechanical tests), in silico (finite elements simulations) and in vivo (clinical survival rates). The in vitro and the in silico studies proved that an appropriate variation of the geometric design of the preparations enables to increase up to 80% the mechanical strength of ceramic reconstructions. The in vivo clinical study of CAD/CAM full ceramic crowns was performed in accordance with the principles stated within the in vitro and the in silico studies and provided a 98.97% success rate over a 6 years period. The variations of geometric design parameters for dental preparation allows for reconstructions with a mechanical breaking up to 80% higher than that of a non-appropriate combination. These results are confirmed in clinical practice.

Influence of temperature and relative humidity on dentin and enamel bonding: a critical review of the literature. Part 1. Laboratory studies.

PURPOSE: The aim of this literature review was to investigate the results from in vitro laboratory studies on the influence of temperature and relative humidity present before polymerization on enamel and dentin bonding systems. MATERIALS AND METHODS: A systematic search was carried out including articles published in English, in peer reviewed journals, and indexed in MEDLINE/PubMed database. The search was carried out using the terms: relative AND humidity AND dental. In vitro studies were retrieved and divided into laboratory simulation studies and studies on physical properties. Laboratory simulation studies were addressed by subtopic: resin-enamel bond strength, resin-dentin bond strength, and dentin-enamel microleakage. Studies on physical properties tested the influence of humidity and temperature through polymerization contraction, flexural strength, and dentin wettability. RESULTS: Laboratory simulation studies demonstrated a strong influence of humidity and temperature on dentin and enamel bond strength and microleakage with dental adhesives systems. The studies on physical properties failed to demonstrate any influence of humidity on the adhesion performance, except for wettability measurement. CONCLUSION: The clinical relevance of these in vitro results remains to be demonstrated. A review of in vivo clinical studies will complete the literature data presented here.

Confocal Raman microscopy and SEM/EDS investigations of the interface between the zirconia core and veneering ceramic: the influence of a liner and regeneration firing.

The aim of this study was to evaluate the changes in the transition layer at the interface between yttria partial stabilized tetragonal zirconia polycrystalline (Y-TZP) core and veneering feldspathic ceramic (VITA VM(®)9), under different manufacturing methods. Confocal Raman microscopy and energy dispersive X-ray spectroscopy (EDS) analyses were carried out on tapered veneered cross sections of the interface. For some samples, an additional firing of the core was used, as the application of an optional liner material between the core and veneer. Single Raman spectra were distinguishable between Y-TZP and the veneering materials. VM(®)9 and liner spectra were broadly superimposable. No substantial differences appeared in their chemical elemental composition. 2D Raman images and EDS analysis emphasized changes in the interdiffusion thickness; the additional firing of the core decreased the interdiffusion zone, and the highest firing temperature of the liner increased the interdiffusion zone. These results, which will help us understand the changes in this transition layer, are discussed.

Confocal Raman microscopic analysis of the zirconia/feldspathic ceramic interface.

OBJECTIVES: Esthetic demands and biocompatibility have prompted the development of all-ceramic dental crowns. Yttria tetragonal zirconia polycrystalline (Y-TZP) framework material has the best mechanical properties compared to other all-ceramic systems, but the interface is the weakest component of core veneered restorations. Confocal Raman microscopy possibilities are used to ensure the understanding of the zirconia-feldspathic ceramic relationship, which is not well known. METHODS: Bilayered zirconia (Vita In-Ceram(®) YZ) veneer (Vita VM(®)9) blocks were manufactured. Raman analyses were performed using two protocols: (1) single spectra, line scans and images on a sectioned and polished specimen and (2) in depth line scans on unprepared specimen. Single spectra, images and line scans provide information about the crystalline phases, their distribution and the existence of a possible diffusion at the Y-TZP/VM(®)9 interface, respectively. The elemental distribution of zirconium (Zr) and silicon (Si) around this interface were investigated using energy dispersive X-ray spectroscopy (EDS). RESULTS: Raman single spectra embodied a unique spectrum (crystalline) on Y-TZP and two spectra (crystalline and amorphous) on VM(®)9; these spectra were clearly distinguished. Raman line scans showed a series of transition spectra across the interface from VM(®)9 to Y-TZP. It emphasized an interdiffusion zone, which was estimated at a maximum of 2 microns, found on 2d Raman images and confirmed by EDS. The elemental distribution with EDS showed a mutual diffusion of Zr and Si and was mainly dominated by Si diffusion in Y-TZP. SIGNIFICANCE: Confocal Raman microscopy highlights an interdiffusion zone at the zirconia-feldspathic ceramic interface. The elemental transition layer is estimated and is supported by EDS analysis as a coupling technique.