Mahidol Dental Journal

An overview of sleep bruxism and management, a review

Jarika Leeraphongnan — 2025-11-07

The concept of sleep bruxism (SB) has evolved over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB. An international consensus was attained on the definition of SB as masticatory muscle activities that occur during sleep (characterized as rhythmic or non-rhythmic). The etiology of bruxism is not well known, but it is believed to be multifactorial. Assessment tools of bruxism may be made by patient report, clinical interview, clinical examination, and instrumental assessment, leading to diagnostic criteria that challenge to provision of scientifically proven information regarding SB management. Several investigations have been carried out to confirm the safety and efficacy of various kinds of treatment aimed at solving bruxism. In addition, the methodological quality, the different criteria of SB diagnosis, and the lack of homogeneity in terms of study design can result in poor meta-analysis data, mislead readers, and induce malpractice. These issues are also discussed.

Effect of accelerated aging on phase transformation and flexural strength of yttria-stabilized tetragonal zirconia dental ceramics

Pichavipa Maluangnon — 2025-11-04

Objectives: The objectives of this study were to investigate the effect of hydrothermal aging on the flexural strength and the transformation behavior of two translucent (Cercon xt ML and Ceramill Zolid FXML) and two conventional (Cercon ht and Ceramill ZI) dental zirconia (Y-TZP).

Materials and methods:Five bar-shaped specimens (1.5 x 4 x 22 mm) of zirconia in each group were subjected to hydrothermal aging process at 134°C under 0.2 MPa for 0, 10 and 50 hours. After aging, the monoclinic-to-tetragonal phase transformation was evaluated using an x-ray diffraction technique. The alteration in material microstructure was observed using a scanning electron microscope. The flexural strength of all specimens was determined using a four-point bending test. Two-way ANOVA was used to analyze the flexural strength values to find the significant differences among groups at α =.05.

Results:The results showed that there was a significant increase in flexural strength of Ceramill ZI and Cercon ht after autoclaving for 10 hours and 50 hours. The flexural strengths of Ceramill Zolid FXML and Cercon xt ML were not significantly different at all autoclaving times. After 50 hours of autoclaving, the monoclinic phase increased from 0.2 to 69.40 wt% for Ceramill ZI, and from 0 to 70.03 wt% for Cercon ht. There was also no relevant effect of aging on grain size or topography at the surface of all Y-TZPs groups.

Conclusions:Prolonged hydrothermal aging caused an increase in monoclinic phase content in conventional dental zirconia and a significant increase in flexural strength was also observed in this group. However, prolonged hydrothermal aging had limited effect on flexural strength and amount of monoclinic phase change observed in the translucent dental zirconia group.

A multi-center retrospective analysis of oral and maxillofacial lesions in the southernmost region of Thailand

Srisuk Khwankong — 2025-11-04

Objectives: This multi-center retrospective study aimed to analyze the demographic distribution, lesion characteristics, and referral patterns of oral and maxillofacial lesions (OMFLs) in Thailand’s three southernmost provinces.

Materials and Methods: Histopathologically confirmed OMFLs diagnosed from 2018-2024 were reviewed using records of four public hospitals representing Thailand’s healthcare system tiers. Lesions were categorized as soft tissue lesions (STLs) or odontogenic and maxillofacial bone tumors (OMBTs), and analyzed by age, sex, anatomical site, and referral level. Statistical analyses included the Mann– Whitney U test and Pearson’s Chi-Square test (p < 0.05).

Results: A total of 512 OMFLs were identified. STLs (53.7%) slightly outnumbered OMBTs (46.3%). Patients with STLs were significantly older than those with OMBTs (median age: 46 [IQR 23-60] vs. 28 [IQR 19-44] years; p < 0.001). The most common STLs were mucosal and soft tissue tumors, particularly irritation fibroma (IF) in the buccal mucosa and pyogenic granuloma (PG) in the gingiva. IF was predominant in patients over 40, while PG mainly affected those under 40. Mucoceles were the most frequent salivary gland lesions in younger patients. Jaw cysts were the most common OMBTs, with radicular cysts more prevalent in the maxilla and dentigerous cysts in the mandible. Ameloblastoma, primarily found in the mandible, was the most frequent odontogenic tumor. Within the four-tier healthcare system of the study area, complex cases tended to escalate to higher tiers. All oral cancer (OC) cases appeared at provincial hospitals (third-tier), as at the regional (highest) level they were diverted to ENT, reflecting interdepartmental separation of case management.

Conclusion: OMFLs in this region show distribution patterns consistent with previous reports. Progressive management trends reflect Thailand’s structured referral system. Lower-tier hospitals can aid OC control through early detection and gatekeeping referral, while bridging interdepartmental gaps may strengthen OC case coordination at the regional level.

Effects of 40% hydrogen peroxide on the surface roughness and biofilm formation of three different types of resin composites

Jantanee Leelanarathiwat — 2025-11-04

Objective: This study aimed to examine the effects of hydrogen peroxide on three different resin composites (Z250: microhybrid, Z250XT: nanohybrid, and Z350XT: nanocomposite) in terms of surface roughness alteration and biofilm formation.

Materials and Methods: Forty-two samples were prepared from each material and then randomly divided into two groups for investigation. In total, 20 samples were used to determine the surface roughness, and the remaining 22 samples were used to determine biofilm formation. Finally, the samples were divided into two subgroups: the bleached group and the nonbleached group. In the bleached group, the samples were bleached with 40% hydrogen peroxide (opalescence boost). The bleaching procedures were conducted following the manufacturer’s instructions. The surface roughness was assessed using an arithmetical mean height of an area (Sa) by a laser scanning microscope. For biofilm measurement, S. mutans was cultured on each sample coated with the acquired pellicle and stained with a Live/Dead Bac LightTM Bacterial Viability Kit. Biofilm formation was measured under a confocal laser scanning microscope.

Results: The surface roughness significantly differed among the three groups of materials without bleaching (p=0.000) and with bleaching (p=0.000). The roughness of Z250 was significantly greater than that of the other two samples, while no significant difference between Z350XT and Z250XT was observed. Compared with that of the samples without bleaching, the surface roughness of the three types of resin composites was significantly different (p<0.05). For biofilm formation, no significant differences among the groups were observed.

Conclusions: Bleaching affected the Sa of three different types of resin composites, but the change in Sa had no effect on the average volume of colonies at the substratum of S. mutans biofilms. The resin-based materials Z250, Z350XT and Z250XT represent potentially suitable materials for aesthetic restoration, and the 40% hydrogen peroxide bleaching agent had no adverse effects.

Fluoride concentration and pH of commercial oat milk products in Thailand

Praphasri Rirattanapong — 2026-01-16

Objective: To determine the fluoride concentration and pH of commercially available oat-milk products sold in Thailand.

Materials and Methods: Thirty-seven oat-milk products (unsweetened n = 14, sweetened n = 23; pasteurized
n = 7, UHT n = 30) were analyzed. Fluoride concentration was measured using an ion-selective electrode and pH with a calibrated pH meter. Independent t-tests compared fluoride concentrations between sweetness types and processing methods (α = 0.05).

Results: Fluoride concentration ranged 0.0058–4.853 ppm (mean 0.95 ± 1.25 ppm) and pH 6.26–7.72
(mean 6.98 ± 0.41). No significant differences were found between sweetened vs unsweetened (p = 0.404)
or pasteurized vs UHT (p = 0.098) products.

Conclusion: Oat-milk products in Thailand show wide variation in fluoride concentration and near-neutral pH. Differences by sweetness type and processing method were not statistically significant.

Innovation of disposable messing gun in endodontics: clinical simulation test

Naphawan Harndamrong — 2026-01-16

Objectives: This study aimed to evaluate a novel disposable delivery system, the MDent Gun, by assessing postgraduate student operator satisfaction and comparing the quality of mineral trioxide aggregate (MTA) apical plugs produced using the MDent Gun versus the OrthoMTA carrier in standardized open-apex resin tooth models.

Materials and Methods: Sixty three-dimensionally printed resin tooth models with standardized open apices were fabricated. Thirty postgraduate endodontic students performed orthograde placement of 4-mm ProRoot MTA apical plugs using both the MDent Gun and OrthoMTA carrier in a randomized crossover design. The MTA was standardized (0.5 g powder:0.18 mL distilled water) and placed under dental operating microscopy. Operator satisfaction was evaluated using a questionnaire assessing: (1) ergonomic design, (2) ease of material extrusion, (3) convenience of intracanal delivery, and (4) suitability for MTA apical plug procedures. Apical plug quality was assessed radiographically using a 4-grade scoring system. Intraobserver reliability was calculated using Cohen’s Kappa coefficient. Statistical analyses were performed using the Wilcoxon signed-rank test for both operator satisfaction and apical plug quality (p < 0.05).

Results: Intraobserver reliability for radiographic scoring demonstrated excellent agreement (Cohen’s Kappa = 0.927, p < 0.001). Operators reported significantly higher ergonomic design satisfaction with the MDent Gun (median 4, IQR 4–5) compared to the OrthoMTA carrier (median 4, IQR 4–4) (p = 0.016). No statistically significant differences were observed for other satisfaction parameters. Radiographic void scores demonstrated no significant differences between the MDent Gun (median 2.5, IQR 1–3) and OrthoMTA carrier (median 2.0, IQR 2–3) groups.

Conclusions: Operators demonstrated significantly higher satisfaction with the ergonomic design of the MDent Gun compared to the OrthoMTA carrier, while MTA apical plug quality showed no significant differences between both delivery systems.

Effect of low-sugar fermented milk with Lactobacillus paracasei 431 on Streptococcus mutans biofilm formation and enamel demineralization: in vitro study

Ruangkhao Phimonsri — 2026-01-19

Abstract
Objectives: This study investigates the effects of Lactobacillus paracasei 431 and sugar content in fermented milk on the growth and biofilm formation of S. mutans, as well as its potential to cause enamel demineralization.

Materials and methods: Two fermented milks were used: 1.) 6% sucrose, and 2.) 0.1% sucrose. S. mutans (ATCC25175) was cultured with fermented milk and filtered fermented milk to remove L. paracasei 431. Firstly, S. mutans growth was determined by using colony-forming units. Secondly, S. mutans biofilm formation was evaluated using a biofilm assay. Thirdly, S. mutans biofilms were grown on enamel slabs, then exposed twice per day to the fermented milks for five days, and surface hardness loss was measured. Biofilms on the enamel slabs were stained with live/dead dye and observed under a confocal microscope. The Kruskal-Wallis test was used to compare differences among groups, and post-hoc test contrasts for every pair of variables were used (Bonferroni Correction). A difference was considered statistically significant if it was p<0.05.

Results: The viable S. mutans count in fermented milk with 6% sucrose was lower than in filter-sterilized milk (p<0.05). Both fermented milks with 6% sucrose and 0.1% sucrose reduced S. mutans biofilm formation compared to filter fermented milk (p<0.05). Fermented milk with 0.1% sucrose showed less demineralization than 6% sucrose, though the difference was not significant (p>0.05).

Conclusions: Fermented milk with Lactobacillus paracasei 431 inhibited S. mutans growth and biofilm formation. No statistically significant difference was observed between fermented milk with 6% and 0.1% sucrose in the percentage of surface hardness loss.