Background The aim of this study was to investigate the microbiome shift of denture biofilm formation, the incidence of Candida and changes of salivary inflammatory markers following insertion of 3-dimensional printed PMMA denture. Methods This was a pilot study of 6 patients provided with 3D printed (test group) or conventionally heat-cured (control group) removable partial acrylic dentures followed up for 6 weeks. 3 denture swabs were collected at week 1, 3 and 6; and saliva samples were collected at baseline, week 1, 3 and 6 following denture insertion. Microbial DNA was isolated, and the 16S rRNA gene was amplified and sequenced to assess the denture microbiota. The presence of Candida was determined using PCR assay. The levels of salivary biomarkers lactoferrin (LTF) and histatin (HTN) were determined using ELISA. Results Denture microbiome of both groups exhibited similar microbial compositions at weeks 1, 3 and 6. However, the percentage of Streptococcus in the test group was significantly lower at week 1 (p<0.05). Greater bacterial diversity was detected in the test group (p<0.05; pairwise Wilcoxon) after 6 weeks. The presence of Candida was only detected in one sample of the 3D printed denture (test group) after 6 weeks. The level of LTF biomarkers increased in both groups after 6 weeks, however, the level of HTN increased only in the control group. Conclusions Denture microbiome of both groups demonstrated similar microbial compositions. After 6 weeks, 3D printed denture demonstrated higher diversity with delayed microbiome shift compared to conventional heat cure dentures. 3D printed denture may be a viable alternative to conventional denture and it has a potential to delay microbial dysbiosis. Clinical Relevance Among wearers, 3D printed denture can potentially reduce the risk of denture stomatitis. A greater diversity may delay or slow the transition of denture microbiome to dysbiosis.

Background: The influence of scaler tip design on root surface roughness, tooth substance loss and patients' pain perception is investigated. Methods: This article was divided into the following parts: Part 1 Surface roughness and substance loss: an in vitro study, which involves intact extracted teeth sectioned and treated using a piezoelectric ultrasonic device (PM200 EMS Piezon, Switzerland) with a conventional scaler tip (FS-407) and a Perio Slim (PS) scaler tip (Perio Slim DS-016A). All sectioned samples for tooth surface roughness (n=20) and tooth substance loss (n=46) analyses were measured and compared using a 3D surface texture analyser and scanning electron microscope (SEM) respectively, at baseline and following scaling. Part 2 Pain Perception: a clinical study, which was a split-mouth study design including 30 participants with gingivitis and/or mild chronic periodontitis; treated with supra-gingival scaling from teeth #13 to #23. Subjects were randomised to group A or group B. Group A was treated first with PS scaler tips, whereas group B was treated first with conventional scaler tips. Pain perception was recorded using the visual analogue scale (VAS). Results: In vitro study: both scaler tips caused significant reduction in root substance roughness after scaling (p<0.05), but no significant difference between the two scaler tips (p>0.05) was observed. The PS scaler tip caused statistically significantly less root substance loss (p<0.05) when the initial thickness of the tooth was <1000 �m. Clinical study: the participants reported significantly lesser pain score during scaling using the PS scaler tip (median: 3) than when using the conventional scaler tip (median: 5) (p<0.05). Conclusions: In the in vitro study, using a slim scaler tip design causes less tooth substance loss compared to a wider scaler tip design. In the clinical study, less pain was observed compared than a wide (conventional) scaler tip design.

This study aimed to provide a comprehensive review of various recent methods that can be used to assess the fit and accuracy of additive-manufactured removable partial dentures (RPDs), focusing on 3D-printed RPDs. An electronic search of the English language literature from January 2000 to February 2022 was performed using four databases: Medline/PubMed, Scopus, Web of Science, and EBSCOhost, using relevant keywords. The parameters of interest were extracted and tabulated. Of 936 retrieved studies, 26 studies were included. Most of the studies were laboratory studies, conducted between 2011 and 2022, did not include control group, used stone cast model as reference, used direct 3D printing method, and polished the final RPD framework. Methods of assessment can be divided into two categories: 1) qualitative assessment which is based mainly on visual inspection or tactile sense, and 2) quantitative assessment which includes optical assessment (with or without a registration material) and computerized assessment based on surface-matching software programs. In conclusion, computerized assessment using different surface matching software provides more accurate and precise quantitative assessment of denture fit and allows researcher and practitioner to detect minute dimensional changes that cannot be detected visually.