Mahidol Dental Journal

Force of colored intermaxillary latex elastics from different suppliers: A comparative in vitro study

2026-01-31T18:06:04+07:00

Background: Colored orthodontic latex elastics are increasingly popular among younger patients, yet their mechanical behavior may vary. Differences in force delivery and degradation over time can compromise treatment efficiency. Understanding the force–extension relationship and relaxation behavior of these elastics is essential to ensure continuous, optimal orthodontic forces.

Objectives: This study evaluated and compared the standard force–extension index (three times the lumen diameter), initial force delivery, and force degradation of colored intermaxillary latex elastics from different manufacturers, with varying lumen diameters and declared force values, under simulated oral conditions.

Materials and Methods: This in vitro study assessed the force characteristics of colored intermaxillary latex elastics from three manufacturers: American Orthodontics® (Sheboygan, WI, USA), AURAdontics, Inc. (Riverside, NJ, USA), and G&H Orthodontics® (Franklin, TN, USA). A total of 180 elastics (15 per group) were tested, yielding 1,080 force measurements. Elastics with declared forces of 4.5 oz from all manufacturers and 6.5 oz elastics from G&H were included in three lumen diameters (3/16, 1/4, 5/16 in). The standard force‑extension index was determined by stretching each elastic to three times its lumen diameter. To simulate oral conditions, elastics were extended to fixed distances (14.29, 19.05, 23.81 mm), immersed in distilled water at 37°C, and measured at baseline and after 1, 3, 6, 12, and 24 hours. Statistical analyses compared force values across manufacturers, lumen diameters, declared force levels, and time intervals.

Results: The standard force–extension index varied from -34.30% to 16.70%. Elastics with declared 4.5 oz forces showed closer agreement with the standard index (mean 1.13%) than 6.5 oz elastics (mean -26.84%). All elastics exhibited rapid force loss within the first hour, followed by a gradual decline. After 24 hours, the remaining force averaged 60.87% for 4.5 oz elastics and 69.71% for 6.5 oz elastics.

Comparison of the bond strength of orthodontic metallic brackets bonded to different tooth-colored restorative materials and the surface roughness of materials before and after removing the brackets

2025-06-04T14:01:49+07:00

Objective: This study aimed to compare the shear bond strength (SBS) of metal orthodontic brackets bonded to different tooth-colored restorative materials and the roughness of the restorations before brackets bonding and after removing the brackets.

Materials and Methods: The 50 specimens (N=50) were divided into 5 groups (n=10), including Resin Composite (RC), Porcelain Leucite-based ceramic (PL), Lithium Disilicate glass (LD), Zirconia (ZR), and Hybrid ceramic (HC). The metal bracket 0.022” MBT™ System 3M™ Unitek™ Gemini Brackets Kit (3M ESPE, St. Paul, USA) was bonded on specimens with Universal Silane coupling agents (Monobond N®: Ivoclar Vivadent, Schaan, LiechtensteinI) and light-cure Transbond™ XT Primer and orthodontic adhesive (3M ESPE, St. Paul, USA). The shear bond strength (SBS) was measured by using a Universal testing machine. Adhesive Remnant Index (ARI) was observed under a stereomicroscope. All specimens were polished using the polishing protocol from the manufacturer’s instructions, and the surface roughness value (Ra) was recorded using Surface Roughness Tester-Stylus for contact to compare the roughness of the surface before and after removing the brackets.

Result: The highest shear bond strength was PL group (6.24 MPa), and the lowest was RC group (3.23 MPa).
The shear bond strength (SBS) was significantly different among groups (p<0.05). For ARI scores, most of the specimens in the PL, HC, LD, and ZR groups scored 3, whereas the RC group scored 1. The surface roughness value (Ra) before and after polishing of all groups except the HC group is significantly different. (p<0.05)

Conclusion: Only PL and ZR show high shear bond strength for orthodontic bonding. All groups, except the RC group, have adhesive failure at the adhesive-bracket interface. Therefore, the need to remove the remaining adhesives and the possibility of damage to the material surface are high. The HC group had non significantly different roughness values compared before bracket bonding and after removing the brackets.

Fluoride concentrations and pH levels of bottled mineral water commercially available in Bangkok, Thailand

2026-01-07T09:54:16+07:00

Objectives: To assess the fluoride concentrations and pH levels of commercially available bottled mineral water in Bangkok, Thailand.
Materials and Methods: Between April and June 2025, 41 brands of bottled mineral water were randomly purchased from retailers across Bangkok. Three bottles with different batch numbers were collected for each brand. Fluoride concentrations were analyzed using a fluoride ion-selective electrode with TISAB II, and pH levels were measured using a calibrated digital pH meter. Fluoride concentrations were compared among brands and among production batches within each brand using the Kruskal–Wallis test with Bonferroni-adjusted post hoc comparisons (α = 0.05).
Results: Fluoride concentrations varied widely among brands, ranging from 0.02 to 1.69 mg/L (p < 0.001).
No significant differences were observed among batches within any brand (p > 0.05). Thai-sourced mineral waters demonstrated the highest fluoride levels and the greatest variability, with four brands containing approximately 1.0 mg/L or higher. pH values ranged from 5.65 to 8.86, with most products falling within the recommended range of 6.5–8.5. Only one of the 41 brands reported fluoride content on its label.
Conclusions: Fluoride concentrations in bottled mineral waters sold in Bangkok show substantial variation, with several Thai-sourced brands exceeding recommended levels for tropical climates. The absence of fluoride labelling limits consumer awareness and complicates clinical assessment of total fluoride intake. Regular monitoring and improved labelling regulations are recommended to reduce the risk of excessive fluoride exposure, particularly in young children.

Dynamic transition of pSTAT3 expression demonstrates the highest level in severe oral epithelial dysplasia before downregulation in invasive carcinoma

2026-02-03T09:21:48+07:00

ThailandThis study aimed to preliminarily evaluate the expression of phosphorylated signal transducer and activator of transcription 3 (pSTAT3) in oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) in comparison with normal oral mucosa (NOM). Additionally, its potential involvement in the sequential process of oral carcinogenesis was investigated. This study included 75 formalin-fixed, paraffin-embedded tissue specimens, comprising 15 cases each of NOM, mild OED, moderate OED, severe OED, and OSCC. Immunohistochemical analysis was performed to evaluate protein expression. The proportion of positive cells and the staining intensity were semi-quantitatively assessed and recorded as an immunoreactive score (IRS). Comparisons of IRS were conducted among the NOM group, the various grades of OED, and the OSCC group using appropriate statistical analyses. pSTAT3 was found predominantly in the nuclei of epithelial cells, with mild cytoplasmic staining observed to a lesser extent. Immunostaining demonstrated a progressive expansion of positivity from the basal layers in NOM to the superficial epithelial layers in severe OED. Based on the IRS, pSTAT3 expression gradually increased from NOM through the OED groups and declined in the OSCC group. The highest IRS was observed in severe OED compared with NOM (p = 0.002). However, pSTAT3 levels significantly decreased in OSCC compared with severe OED (p = 0.007). pSTAT3 expression progressively increases from NOM to OED, with expansion from basal to full epithelial thickness as the severity of dysplasia increases. These results imply a role of pSTAT3 in early oral carcinogenesis.

Clinical measurement on eyes and periocular areas: A Khon Kaen University study

2026-02-09T14:27:18+07:00

There is still no available dataset on the dimensions of prefabricated ocular prostheses for the Northeastern Thai population. This pilot study aimed to report on pupil positioning, iris and scleral dimensions, and lateral eye curvatures among individuals at the Faculty of Dentistry, Khon Kaen University. It also explored the correlations between these measurements and key demographic variables, including age groups and gender. A total of 276 healthy participants were categorized by gender and further subdivided into three age groups: 20–30, 31–50, and >50 years. Standardized photography was conducted in a well-lit room. A Whibal card with a 10-mm scale was held perpendicularly to the subject. Its inner edge was positioned adjacent to the right nostril, and its top edge was placed 1 cm below the lower eyelid. Measurements included interpupillary distance (IPD), outer canthal distance (OCD), intercanthal distance (ICD), palpebral fissure width (PFW), palpebral fissure height (PFH), iris size, and the angles between the upper and lower eyelids. Group comparisons were conducted using t-tests and one-way ANOVA, with Tukey’s post hoc tests (p = 0.05). Gender significantly influenced IPD, OCD, PFW, and the upper-lower eyelid angle. Age significantly affected iris size, which was larger in the 20–30 group than in the >50 group. PFH was greater in the 20–30 group than in the >50 group and lower in the >50 group than in the 31–50 group. The upper-lower eyelid angle was more obtuse in the >50 group than in the 20–30 group. Males exhibited age-related differences in IPD, PFW, and eyelid angle, while females showed variations in iris size and PFH. These findings provide baseline periocular measurements which can be utilized to enhance the accuracy of stock ocular prostheses for the Northeastern Thai population.

Oral health promotion via teledentistry for homebound and bed-ridden patients in Thailand: case reports exploring feasibility and user satisfaction

2025-08-14T05:49:35+07:00

Evidence on teledentistry for oral health promotion in developing countries remains limited. This report presents a series of case reports from a pilot teledentistry programme implemented for homebound and bed-ridden patients in Thayang District, Phetchaburi, Thailand. Twenty-three patients (mean age 74.2 years; range 57–92) who were registered under the local home-visit service participated in the programme. These cases illustrate how teledentistry was incorporated into routine care to support oral health assessment, education, and follow-up.

Of the 23 cases, 20 patients (87%) successfully used the Teledent system with assistance from caregivers, village health volunteers, dental hygienists, or independently. Pre- and post-test oral health education results showed improvement across all three oral-condition groups, although the tests were descriptive and used solely to support case documentation. User satisfaction was high, with an average score of 6.49 out of 7 on the Thai Telehealth Usability Questionnaire (T-TUQ). The most common challenges reported were technical limitations and unfamiliarity with the technology.

These case reports demonstrate that teledentistry can be feasibly integrated into routine home-visit services to enhance oral health promotion for homebound and bed-ridden patients. The findings highlight practical considerations for implementation and suggest that teledentistry may be a promising supplementary approach in underserved settings.

Dens invaginatus: diagnostic and therapeutic challenges of a rare developmental dental anomaly

2025-10-06T17:28:13+07:00

Dens invaginatus (DI) is a rare developmental dental anomaly resulting from the invagination of the enamel organ into the dental papilla during odontogenesis. This condition leads to a broad spectrum of morphological variations, with maxillary lateral incisors being the most frequently affected. The resulting deep pits or invaginations often communicate with the oral cavity, creating ideal environments for bacterial retention. This anatomical irregularity predisposes affected teeth to early onset dental caries, pulpitis, and, if untreated, progression to periapical pathology and soft tissue necrosis. Radiographically, dens invaginatus typically appears as a radiolucent tract surrounded by radiopaque enamel, limited to the crown or extending into the root. The complexity of the internal anatomy poses significant diagnostic and therapeutic challenges, particularly in endodontic management. Management strategies vary depending on the type and severity of the anomaly, ranging from preventive sealing to advanced endodontic procedures such as nonsurgical root canal therapy (NS-RCT), apexification, regenerative endodontic procedures (REPs), surgical root canal treament (S-RCT), or intentional replantation. Regardless of the classification, the invaginated tract should always be addressed, and NS-RCT is indicated when irreversible pulpitis or necrosis is present. This review explores the etiopathogenesis, classification, histopathology, diagnostic approaches, and evidence-based treatment modalities for DI, emphasizing the importance of early diagnosis and tailored management strategies to preserve teeth that were once considered non-restorable.

Effect of periodontitis treatment on renal function in chronic kidney disease patients: a systematic review and meta-analysis

2025-09-11T09:43:10+07:00

To evaluate the effect of non-surgical periodontal therapy (NSPT) on renal function and systemic inflammatory markers in patients with chronic kidney disease (CKD). A systematic literature search was conducted in PubMed, SCOPUS, EMBASE, and the Cochrane Library for articles published up to October 2025, strictly following PRISMA guidelines. The protocol was registered in PROSPERO (CRD42021232030). Eligible studies included clinical trials and before-after studies evaluating the effect of NSPT on renal parameters (eGFR, serum creatinine, BUN, UACR) in patients with CKD. Meta-analyses were performed using random-effects models and stratified by CKD stage (pre-dialysis vs. dialysis). Ten studies (seven before-after studies and three randomized controlled trials) met the inclusion criteria. The overall pooled meta-analysis indicated that NSPT did not significantly improve traditional renal filtration parameters. In subgroup analyses, pre-dialysis patients demonstrated a modest, but non-significant trend toward improved eGFR. Among dialysis patients, serum creatinine and eGFR showed no significant improvement and occasionally increased, which may paradoxically reflect altered nutritional status rather than a deterioration in renal filtration. Although NSPT does not result in statistically significant improvements in traditional renal filtration markers, it effectively reduces systemic inflammatory burden in both pre-dialysis and dialysis patients. Integrating periodontal care into multidisciplinary CKD management remains crucial for minimizing inflammation-driven cardiovascular risks. Future robust, long-term trials targeting pre-dialysis populations and utilizing highly sensitive novel biomarkers are warranted to evaluate potential slowing of CKD progression.