Khon Kaen University Dental Journal

Oral Functional Decline in Thai Older Adults: A Systematic Review and Narrative Synthesis

2026-02-18T08:45:55+07:00

Objective: The decline in oral function is a growing concern among the aging Thai population, affecting nutrition, general health, and quality of life. This systematic review aimed to map the current landscape of research regarding oral functional decline in the older Thai population.

Materials and Methods: A systematic search was conducted in PubMed and Thai local journals for studies published between 1993 and 2025. Eligible studies included randomized controlled trials, quasi-experiments, observational studies, qualitative research, and mixed-methods. Studies were included if they involved Thai individuals aged 60 or older with reported oral function outcomes. Three reviewers independently performed study selection, data extraction, and quality appraisal.

Results: Among the total of 4,292 publications, 11 were selected according to the inclusion criteria, including 2 experimental and 9 non-experimental studies. The prevalence of chewing difficulty among older Thai adults ranged from 0.6–72%, while swallowing problems ranged from 8–59.4%. Xerostomia and hyposalivation were reported at 23–38.4% and 16.4–43.5%, respectively. Speaking problems showed the lowest prevalence, ranging from 3.5–5.6%.

Conclusion: Oral functional decline is prevalent among elderly Thais. However, the evidence remains unclear due to heterogeneity in study designs and assessment methods. Public health strategies should enhance access to oral healthcare and integrate it into broader aging care services in Thailand.

An In Vitro Comparative Evaluation of the Effect of Two Chelating Agents and Irrigation Techniques on the Push-Out Bond Strength of a Bioceramic-Based Sealer

2026-02-10T15:16:53+07:00

Objective: To compare the push-out bond strength (PBS) and failure modes of root canals obturated with gutta-percha and a bioceramic-based (BC) sealer after final rinsing with either 17% EDTA or 0.2% chitosan, using conventional syringe irrigation and passive ultrasonic irrigation (PUI).

Materials and Methods: Fifty-two extracted human mandibular premolars were selected and sectioned to obtain 16-mm root lengths. The canals were prepared using ProTaper Next rotary files up to size X3 and randomly divided into four groups (n = 13 per group) according to the final irrigant and irrigation method; Group 1: Syringe irrigation with 17% EDTA, Group 2: PUI with 17% EDTA, Group 3: Syringe irrigation with 0.2% Chitosan and Group 4: PUI with 0.2% Chitosan. The root canals were filled with gutta-percha cone size X3 and BC sealer (CeraSeal) using matched single cone technique. After being kept at 37°C and 100% humidity for 2 weeks to allow setting of sealer, the samples were cut at 5 mm from root apex to achieve 2 mm in thickness of dentin disc as the representative of middle 1/3 of root canal. Mechanical dislodgement resistance was examined using a universal testing machine and PBS was calculated. Specimens were examined under stereomicroscope at 40× magnification to define the bond failure mode. One-way analysis of variance (ANOVA), followed by Bonferroni’s post hoc tests, was performed to evaluate the differences in PBS among the groups. Mode of failure was analyzed by Fisher exact test. The level of significance was set at p=0.05.

Results: There were no significant differences in the mean PBS values or failure modes among the experimental groups. Mean PBS values were 1.67±0.76 MPa, 1.88±0.75 MPa, 1.55±0.80 MPa, and 2.29±1.32 MPa for Groups 1–4, respectively. No significant differences were observed among the groups (p=0.202). Likewise, failure mode distributions were not significantly different among the experimental groups (p=0.209).

Conclusion: No significant differences in PBS or failure mode were observed between root canals irrigated with 17% EDTA and those irrigated with 0.2% chitosan.

Effect of Cleansing Methods on Color Change in Rubber Compound and MDX 4-4210 Silicone Elastomer

2026-05-28T13:25:12+07:00

Objective: To compare color changes in rubber compound and MDX 4-4210 silicone elastomer after cleaning with tap water, 2% chlorhexidine, soap, or microwave irradiation at 6, 12, and 18 months.

Materials and Methods: Disc-shaped specimens of rubber compound and MDX 4-4210 silicone elastomer were prepared (50 specimens per group; 8 groups; total n=400). The specimens were stored in opaque containers and subjected to different cleansing methods simulating 6–18 months of use. Color was measured using a spectrophotometer before cleaning and after each simulated time interval. Color changes within groups were analyzed using the Friedman test, and comparisons between groups were performed using the Mann–Whitney U test because the data were not normally distributed.

Results: Microwave irradiation produced the lowest color change in both materials and did not result in clinically perceptible color change after 18 months of simulated cleansing. In the microwave group, rubber compound showed lower ΔE* values than MDX 4-4210 silicone elastomer at 6 and 18 months, whereas no significant difference was found at 12 months. Soap and tap-water cleansing produced clinically perceptible color changes in rubber compound at 6 and 12 months, respectively. In contrast, MDX 4-4210 silicone elastomer showed clinically perceptible color changes after cleansing with 2% chlorhexidine and soap at 18 months.

Conclusion: Within the limitations of this in vitro study, microwave irradiation resulted in the least color change in both materials, whereas soap cleansing produced the greatest color instability, particularly in rubber compound. Therefore, if rubber compound is to be considered for clinical application, limitations related to cleansing method, cleansing frequency, and expected service duration should be carefully considered.

Comparison of Surface Hardness among Acrylic, Cross-linked Acrylic, and Composite Resin Artificial Denture Teeth: An In Vitro Study

2026-04-17T16:22:24+07:00

Objective: This experimental study aimed to compare the Vickers surface hardness of different types of artificial denture teeth.

Materials and Methods: A total of 72 posterior artificial denture teeth were prepared and divided into four groups (n=18). The groups consisted of Yamahachi FX (Yamahachi Dental MFG.), classified as conventional acrylic resin teeth; VITA MFT (VITA Zahnfabrik) and Livera alpha (Shofu Inc.), classified as cross-linked acrylic resin teeth; and Endura (Shofu Inc.), classified as composite resin teeth. Each specimen was sectioned in an occluso-gingival direction, 1 mm below the deepest point of the central pit. The specimens were then polished and tested for surface hardness using the Vickers hardness test under a 50-g load for 15 seconds. The mean surface hardness values were statistically analyzed using one-way analysis of variance, followed by Bonferroni post hoc test. The level of statistical significance was set at p<0.05.

Results: The mean surface hardness values of Yamahachi FX, VITA MFT, Livera alpha, and Endura artificial teeth were 20.41±0.24, 20.40±0.14, 20.28±0.27 and 30.48±0.25 kgf/mm², respectively. Endura artificial teeth showed significantly higher mean surface hardness than the other groups (p<0.05), whereas no significant differences were found among the other three groups.

Conclusion: Composite resin artificial teeth demonstrated significantly higher Vickers surface hardness than conventional acrylic resin teeth and cross-linked acrylic resin teeth (p<0.05). In this study, Endura, which is classified as a composite resin artificial tooth, exhibited the highest surface hardness, while Yamahachi FX, VITA MFT, and Livera alpha showed no significant differences.

Marginal Adaptation of Autopolymerized, Heat-Cured, Milled Polymethyl Methacrylate, and Three-dimensional Printed Methacrylate-Based Resin Provisional Crowns using Triple Scan Technique: An in vitro Study

2026-06-19T17:03:33+07:00

Objective: To compare the marginal adaptation of provisional crowns fabricated by four different fabrication methods using three-dimensional analysis.

Materials and Methods: Forty standardized resin dies simulating a prepared tooth were randomly assigned to four experimental groups (n=10/group). Provisional crowns were fabricated using autopolymerized polymethyl methacrylate (Unifast TRAD), heat-cured polymethyl methacrylate (SR Ivocron), milled polymethyl methacrylate (DD provi P HI), and three-dimensional printed methacrylate-based resin (Temp C&B UV 2.0). After temporary cementation with Temp-Bond NE under a standardized load, the marginal gap was assessed using a triple-scan protocol and three-dimensional inspection software (Geomagic Control X). Eight circumferential reference sites were evaluated for each specimen. Data were analyzed using one-way analysis of variance and Tamhane T2 post hoc tests (α=0.05).

Results: Fabrication method significantly affected the marginal gap (F=56.256, p<0.001). The milled group showed the smallest mean marginal gap (69.45±15.20 µm), followed by the three-dimensional printed group (72.43±9.29 µm), heat-cured group (108.33±5.57 µm), and autopolymerized group (113.24±5.65 µm). The digitally fabricated groups demonstrated significantly smaller marginal gaps than the conventionally fabricated groups (p<0.001).

Conclusion: Within the limitations of this in vitro study, fabrication method significantly influenced marginal adaptation. Milled and three-dimensional printed provisional crowns showed smaller marginal gaps than conventionally fabricated autopolymerized and heat-cured provisional crowns. However, no significant difference was found between the two digital fabrication methods or between the two conventional fabrication methods. For provisional restorations in which marginal accuracy is particularly important, clinicians may consider either milling or three-dimensional printing instead of conventional fabrication methods.