Marginal Gap and Internal Fit of Fixed Dental Prostheses Fabricated Using Intraoral vs Extraoral Scanning: A Systematic Review and Meta-analysis.

PURPOSE: To compare the marginal gap and internal fit of fixed dental prostheses (FDPs) fabricated using intraoral vs extraoral scanning methods. MATERIALS AND METHODS: MEDLINE/PubMed and the Cochrane database were searched. The focused PICO question was: For the fabrication of FDPs, does an intraoral scanning technique result in a different marginal gap than an extraoral scanning technique? The secondary outcome assessed was internal fit. Studies were selected based on the inclusion criteria, and a meta-analysis was performed. RESULTS: A total of 14 studies (10 in vitro and 4 in vivo) were included in the meta-analysis. Marginal gap in single crowns was evaluated in 5 studies, copings for single crowns in 5 studies, three-unit FDPs in 3 studies, and both single-crown and three-unit FDPs in 1 study. Significantly lower marginal gap was found with intraoral scanning compared to impression scanning (P < .001) and cast scanning (P < .001), and for impression scanning compared to cast scanning (P = .037). Internal fit was superior with intraoral scanning compared to impression scanning, and this difference was significant (P < .001). No significant differences were found in internal fit with cast scanning compared to intraoral or impression scanning. The mean marginal gap/internal fit was 188.3 µm/146.2 µm with intraoral scanning, 116.29 µm/168.2 µm with impression scanning, and 195.1 µm/229.1 µm with cast scanning. CONCLUSION: Marginal gap was lower with intraoral scanning than with impression scanning and cast scanning. Impression scanning showed less marginal gap than cast scanning. Internal fit with intraoral scanning was superior to impression scanning, but when compared to cast scanning, no difference was found.

A cross-sectional virtual survey to evaluate the outcome of online dental education system among undergraduate dental students across India amid COVID-19 pandemic.

PURPOSE: A questionnaire-based study was conducted to understand the pros and cons of online education among undergraduate dental students across India. The study was also proposed to assess the mental and physical well-being of the students amid the COVID-19 pandemic lockdown. METHODS: A total of 533 undergraduate dental students across India participated in a cross-sectional study by means of virtual survey. A self-designed questionnaire was created using google forms. The questionnaire consisted of 25 questions and was divided into two parts, first, regarding the academic outcome of online dental education and second, psychological and physical well-being of the students in reference to online dental education. A descriptive statistical analysis was done using IBM SPSS statistics software. RESULTS: In the present study, 91.6% students reported that the format of dental education was shifted to online lectures due to the COVID-19 pandemic. 86.4% students suggested that they preferred offline lectures rather than online lectures. Psychological and physical well-being were affected in both male and female students; however, male students were affected more significantly than females. CONCLUSION: The study concluded that the education of dental students was adversely affected as a result of COVID-19 pandemic. The physical and psychological well-being of the students has also been affected, with males being affected in a higher proportion. The study concluded that the quality of online education should be enhanced and must be student centred to meet their education requirements. Also, there is a need of regular counselling and other measures to alleviate the students from the psychological stresses.

Stress distribution around different abutments on titanium and CFR-PEEK implant with different prosthetic crowns under parafunctional loading: A 3D FEA study.

AIM & OBJECTIVES: Clinical trials had concluded a significant relationship between implant failure and bruxism. A three-dimensional (3D) finite element analysis (FEA) was done to evaluate the stress distribution in straight and angled abutments around titanium and carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implant with 2 different prosthetic crowns under parafunctional loading. MATERIALS AND METHOD: Twelve 3D models of bone block were created representing the maxillary right premolar area with osseointegrated implants. The models were divided in two group; CFR-PEEK implant (n â€‹= â€‹6) and group titanium implant (n â€‹= â€‹6).Each group was subdivided based on implants with three different abutments (straight, 15°, 25° angled abutments) and having two different prosthetic crowns: porcelain fused to metal (PFM) and polyetheretherketone (PEEK). A vertical load of 1000 â€‹N was applied to the central fossa and an oblique load of 500 â€‹N (30°) was applied to the buccal incline of the palatal cusp. The von Mises stresses and principal stresses were analyzed using ANSYS software. RESULTS: CFR-PEEK and titanium implants produced similar stress in bone under vertical and oblique loading. Straight abutment showed better results than 15° and 25° angled abutments in all the groups. PEEK crown produced lesser stress than PFM crown under vertical and oblique loading. CONCLUSION: The study concluded that straight abutment along with PEEK crown could be given in patients with bruxism to reduce the stress concentration in bone, thus preventing possible implant failure. Titanium and CFR-PEEK implants with straight abutments if given, then it should be provided with an occlusal splint.

Identification of anterior loop in different populations to avoid nerve injury during surgical procedures-a systematic review and meta-analysis.

Exact recognition of the anterior loop is very important to avert any injury to the neurovascular bundle during surgical procedures. The purpose of this review was to evaluate the prevalence and length of the anterior loop in different populations. A comprehensive search of Medline/Pubmed and Cochrane database was done. The focused question was the presence of anterior loop (including loop length) of the inferior alveolar nerve in mental foramen region in CBCT images of the various subjects. Articles related to the presence of anterior loop (including loop length) were only included. Initial literature search resulted in 3024 papers, after removing duplicate articles, 2821 articles were left. Two thousand seven hundred eighty-four articles were further excluded by the reviewers after screening the abstracts which resulted in 37 studies. Hand searching resulted in 2 additional papers. Seven full-text articles were excluded for not fulfilling the inclusion criteria. Finally, 32 articles were included in the review. Two thousand five hundred three subjects with anterior loop were found, which approximates 38% with 48.4% bilateral, 27.8% right side, and 23.8% left side. The loop distribution in males and females was also found to be different. There was highly significant (P < 0.001; I2 = 98.81%) heterogeneity found in the included studies. Variations were found in the prevalence, length, gender, and side distribution of anterior loop in various populations. This systematic review highly recommends not relying on any average values and the clinician should compulsorily make use of imaging modalities available in each and every case, wherever surgical procedure is to be performed near mental foramen region.

Evaluation of stress distribution in an endodontically treated tooth restored with four different post systems and two different crowns- A finite element analysis.

AIM AND OBJECTIVES: The study evaluated the stress distribution in an endodontically treated tooth with four different post systems and restored with two different prosthetic crown materials using finite element analysis (FEA). MATERIAL AND METHODS: A total of eight 3D FEA models of maxillary central incisor were created and divided into two groups; group porcelain fused to metal (PFM) crown (n = 4) and group PEEK crown (n = 4). The endodontically treated tooth was restored using four different post materials such as fiber-reinforced composite (FRC), carbon fiber-reinforced polyetheretherketone (CFR-PEEK), glass fiber reinforced polyetheretherketone (GFR-PEEK) and polyetherketoneketone (PEKK) and composite resin core. A static load of 100 N was applied and von Mises stress was calculated. The stress ratio in dentin was analyzed by using the Mohr-Coulomb failure theory. RESULTS: In dentin, under the applied forces for both, PFM group and PEEK group, it was observed that CFR-PEEK post exhibited minimum von Mises stress while PEKK post exhibited maximum von Mises stress values. The result obtained showed that low stresses were detected using CFR-PEEK post than FRC, GFR-PEEK, and PEKK posts. CONCLUSION: Stress observed in dentin, when CFR-PEEK post was used was lesser in comparison to the FRC post. It was noted that PEEK crown and the PFM crown showed similar effect in dentin in stress generation. Hence, PEEK crown can be used as an alternative to the PFM crown.