Investigation on the Effectiveness of Digital Scanning Combined with Reverse Engineering Technology in Demonstrating Full Crown Tooth Preparation.

OBJECTIVE: To investigate the effect of digital scanning combined with reverse engineering technology in the demonstration of full crown tooth preparation. METHODS: Thirty-one students were randomly divided into the two groups. The students in the control group carried out traditional demonstration by the use of eye-measurement methods. The students in the experimental group carried out improved demonstration by the use of digital intraoral scan with 3D measurement data. The students in both groups were provided with two resin teeth to conduct full crown tooth preparation on head model dental simulators. The teeth prepared before and after demonstration were scored by Chinese Stomatological Association Group Standards, with a total score of 100 points. Analysis of covariance was performed to comparatively analyze the scores related to the tooth surfaces, and convergence angle between two groups. RESULTS: Analysis of two prepared teeth (tooth #11 and #16) in two groups showed that there was a statistical significant difference in the mean score between the control group and experimental group (tooth #11, P = 0.0039) (tooth #16, P = 0.0120).The demonstration of the tooth #16 showed that there were statistical significant differences in the scores related to buccolingual surface (P = 0.0205) and proximal surface (P = 0.0023) between the control group and experimental group; There was a statistical significant difference in the score related to the convergence angle of buccolingual surface between the control group and experimental group (P = 0.0265). CONCLUSION: The digital methods can effectively improve the quality of tooth preparations and has a pedagogical advantage for posterior teeth, which present greater operational challenges.

Accurate mandibular canal segmentation of dental CBCT using a two-stage 3D-UNet based segmentation framework.

OBJECTIVES: The objective of this study is to develop a deep learning (DL) model for fast and accurate mandibular canal (MC) segmentation on cone beam computed tomography (CBCT). METHODS: A total of 220 CBCT scans from dentate subjects needing oral surgery were used in this study. The segmentation ground truth is annotated and reviewed by two senior dentists. All patients were randomly splitted into a training dataset (n = 132), a validation dataset (n = 44) and a test dataset (n = 44). We proposed a two-stage 3D-UNet based segmentation framework for automated MC segmentation on CBCT. The Dice Similarity Coefficient (DSC) and 95% Hausdorff Distance (95% HD) were used as the evaluation metrics for the segmentation model. RESULTS: The two-stage 3D-UNet model successfully segmented the MC on CBCT images. In the test dataset, the mean DSC was 0.875 ± 0.045 and the mean 95% HD was 0.442 ± 0.379. CONCLUSIONS: This automatic DL method might aid in the detection of MC and assist dental practitioners to set up treatment plans for oral surgery evolved MC.

Sicca Symptoms, Oral Health Conditions, Salivary Flow and Oral Candida in Sjögren's Syndrome Patients.

This study aimed to investigate the relationships among sicca symptoms, oral health conditions, salivary profiles and oral Candida in Sjögren's syndrome (SS) patients. Eighty-five SS patients (mean age = 50.5) and 40 healthy non-SS individuals (mean age = 51.4) were recruited. They self-completed the Sicca Symptoms Inventory (SSI). Decayed, missing and filled surface (DMFS) scores, salivary flow rates, pH and oral Candida colonization were determined. Mean SSI summary scores of SS patients and non-SS individuals were 11.1 and 5.4 respectively (p < 0.001). The most prevalent sicca symptoms in SS patients were eye irritation (93%), dry throat or nose (88%) and need of fluid for mouth wetting (88%). SS patients had significantly lower whole salivary flow rates than the non-SS individuals. Candida strains were isolated from over 60% of SS patients but not in non-SS patients. C. albicans was the predominant species. SSI summary score was negatively correlated to salivary flow rates while SSI summary and domain scores were positively correlated to the number of filled surfaces (FS) and DMFS scores and oral Candida counts. In conclusion, SS patients had more severe sicca symptoms than non-SS individuals. SSI scores were negatively correlated to the salivary flow rates but positively correlated to caries experience and oral Candida colonization.

A randomized, double-blind, placebo-controlled clinical trial of fluoride varnish in preventing dental caries of Sjögren's syndrome patients.

BACKGROUND: Sjögren's syndrome (SS) patients are prone to caries development due to reduction of salivary flow. Topical fluoride is commonly prescribed for caries prevention. METHODS: In this 24-month randomized, double-blind, placebo-controlled clinical trial, SS patients were randomly assigned to receive either fluoride varnish or placebo gel quarterly. Development and arrest of caries at the coronal and root surfaces were recorded at 12-month and 24-month and compared to that of the baseline. Effect of fluoride varnish on oral Candida and lactobacilli colonization was explored by comparing baseline oral microbiological assessments to data obtained at 12-month and 24-month. RESULTS: Seventy-eight SS patients (mean age = 50 years, 2 men) completed this trial. At 24-month, the mean new coronal enamel caries were 1.6 surfaces in both groups, and new dentin caries were 1.4 and 2.7 surfaces in the fluoride and placebo group respectively (p > 0.05). Mean arrested caries were 0.6 and 0.7 surfaces for fluoride and placebo groups respectively and that of root caries were 0.3 and 0.1 surfaces (p > 0.05). The mean oral Candida count was reduced by 30 % in the fluoride group but increased 61 % in the placebo group while no change in oral lactobacilli counts in both groups at 24 months (p > 0.05). SS patients receiving fluoride varnish were significantly less likely to develop dentin caries (p < 0.05). In contrast, those with high baseline DMFS scores (p = 0.05), harbored mixed Candida species (p < 0.05), or unstimulated whole saliva at low pH (p < 0.01) were significantly more likely to develop dentin caries. CONCLUSIONS: Results of this randomized clinical trial did not provide clear evidence to support or refute that quarterly applications of fluoride varnish can prevent development of dental caries in people with Sjögren's syndrome. TRIAL REGISTRATION: This study was retrospectively registered at the ISRCTN registry ( ISRCTN85164658 ) on 9 Sept 2016 and was funded by the Research Grant Council of Hong Kong.

[Validation of a Chinese version of the oral health impact profile-14].

OBJECTIVE: To translate the original English version of oral health impact profile (OHIP)-14 into Chinese version and to test the psychometric properties of the Chinese version for use among the Chinese adults. METHODS: The original English version of OHIP-14 was translated into Chinese, and pre-tested and cross-cultural adapted. Subsequently the Chinese version with a general questionnaire was administered to adults aged 18 approximately 65 years by a trained interviewer. Reliability of the translated scale was assessed in terms of internal consistency using Cronbach's alpha and corrected item-total correlation. Construct validity was evaluated by factor analysis and criterion-related validity was evaluated by examining the associations between perceived oral health status, perceived need for dental care and OHIP-14 scores. Formal psychometric properties were tested according to the standard procedure of the international quality of life assessment (IQOLA) project. RESULTS: A total of 592 adults were surveyed. There were 550 valid questionnaires involving 38 ones with missing data. Cronbach's alpha of the translated scale was 0.93, corrected item-total correlation ranged from 0.53 to 0.71. The 14 items were divided into four domains. There was certain logical relation between the items in the same domains. There was highly significant association between perceived oral health status, perceived need for dental care and OHIP-14 scores. CONCLUSIONS: The translated Chinese version of OHIP-14 demonstrated good reliability and validity. Its good psychometric properties provide the theoretical evidence for further use in Chinese population. It is available for use by researchers in oral health related quality of life studies in Chinese adults.