Three-dimensional Changes of Maxillary Alveolar Morphology After Using Modified Nasoalveolar Molding in Patients with Complete Unilateral Cleft lip and Palate.

OBJECTIVE: This study aimed to evaluate the three-dimensional changes in maxillary alveolar morphology after using modified NAM in patients with complete unilateral cleft lip and palate. DESIGN: This is a retrospective study. SETTING: The study was carried out in the dental hospital, Faculty of Dentistry of Naresuan University, Phitsanulok, which serves as a tertiary care center. PATIENTS: The population sample consisted of 19 patients with nonsyndromic complete unilateral cleft lip and palate. INTERVENTION: All patients received the modified NAM treatment based on the treatment protocol of the Naresuan University Cleft and Craniofacial Center, Thailand. MAIN OUTCOME MEASURE: Dental models obtained at pre-treatment (T0) and post-treatment (T1) were scanned to construct the digital models. The maxillary digital models that showed dimensional changes between T0 and T1 were measured using a computer graphic software. RESULTS: The modified NAM resulted in a significant decrease in the anterior cleft width, posterior cleft width, and anterior arch width. Conversely, it caused a significant increase in the length of the lesser cleft segment and the greater segment rotation. However, the change in the height of both segments and posterior arch width was not found to be significant. CONCLUSIONS: The modified NAM was an effective device for reducing the alveolar cleft width while improving the alignment of alveolar cleft segments.

Effect of the different debonding strength of metal and ceramic brackets on the degree of enamel microcrack healing.

OBJECTIVE: This study aims to determine shear debonding strength of metal and ceramic brackets, and the degree of enamel crack healing. MATERIAL AND METHODS: Extracted human maxillary premolars were flattened on the buccal surface, and randomly separated into five groups (n = 15). In control groups (groups 1 and 2), metal and ceramic brackets were bonded on flat polished enamel, while in experimental groups (groups 3 and 4), metal and ceramic brackets were bonded on the surface with boundary where corner cracks were created. Additionally, fifteen specimens (group 5) were also prepared for an indentation procedure with no bracket installation. The degree of crack healing was measured. All brackets were detached with a universal testing machine, and the adhesive remnant index (ARI) was also identified. Healing degree and apparent fracture toughness were then calculated. RESULTS: Between groups with similar bracket types, there was no statistically significant difference in debonding strength. Regarding bracket types, ceramic brackets provided significantly higher debonding strength than metal brackets. There was a significant difference in ARI scores between metal and ceramic brackets. The corner cracks showed signs of healing in both horizontal and vertical directions. No statistically significant difference in the healing rates among the groups was found and the apparent fracture toughness increased from the initial to the final measurement. CONCLUSIONS: Within the limitations of this study, even though ceramic brackets required significantly higher debonding force compared to metal brackets, debonding stress was limited to the bonding site and did not affect the surrounding cracks on enamel.

Effect of the different debonding strength of metal and ceramic brackets on the degree of enamel microcrack healing

ABSTRACT Objective: This study aims to determine shear debonding strength of metal and ceramic brackets, and the degree of enamel crack healing. Material and Methods: Extracted human maxillary premolars were flattened on the buccal surface, and randomly separated into five groups (n = 15). In control groups (groups 1 and 2), metal and ceramic brackets were bonded on flat polished enamel, while in experimental groups (groups 3 and 4), metal and ceramic brackets were bonded on the surface with boundary where corner cracks were created. Additionally, fifteen specimens (group 5) were also prepared for an indentation procedure with no bracket installation. The degree of crack healing was measured. All brackets were detached with a universal testing machine, and the adhesive remnant index (ARI) was also identified. Healing degree and apparent fracture toughness were then calculated. Results: Between groups with similar bracket types, there was no statistically significant difference in debonding strength. Regarding bracket types, ceramic brackets provided significantly higher debonding strength than metal brackets. There was a significant difference in ARI scores between metal and ceramic brackets. The corner cracks showed signs of healing in both horizontal and vertical directions. No statistically significant difference in the healing rates among the groups was found and the apparent fracture toughness increased from the initial to the final measurement. Conclusions: Within the limitations of this study, even though ceramic brackets required significantly higher debonding force compared to metal brackets, debonding stress was limited to the bonding site and did not affect the surrounding cracks on enamel.

RESUMO Objetivo: O presente estudo teve como objetivo determinar a resistência ao cisalhamento de braquetes metálicos e cerâmicos, e o grau de reparo de fraturas no esmalte. Métodos: Pré-molares superiores, extraídos de humanos, foram aplainados na face vestibular e aleatoriamente divididos em cinco grupos (n = 15). Nos grupos controle (Grupos 1 e 2), os braquetes metálicos e cerâmicos foram colados em esmalte liso e polido; enquanto nos grupos experimentais (Grupos 3 e 4), os braquetes metálicos e cerâmicos foram colados em superfície delimitada, em cujos cantos foram criadas fissuras. Adicionalmente, foram também preparados 15 espécimes (Grupo 5) para um teste com indentação, sem a instalação de braquetes. O grau de reparo das fraturas foi avaliado. Todos os braquetes foram descolados usando uma máquina universal de testes, e o índice de adesivo remanescente (ARI) também foi avaliado. O grau de reparo e a tenacidade à fratura aparente foram então calculados. Resultados: Entre os grupos com o mesmo tipo de braquetes, não houve diferença estatisticamente significativa na força de descolagem. Com relação aos tipos de braquetes, os cerâmicos apresentaram uma força de descolagem significativamente maior do que os metálicos. Houve uma diferença significativa nos escores ARI entre os braquetes metálicos e os cerâmicos. As fraturas de canto mostraram sinais de reparo nos sentidos horizontal e vertical. Não foi detectada diferença estatisticamente significativa no grau de reparo entre os grupos, e a tenacidade à fratura aparente aumentou da mensuração inicial para a final. Conclusão: Considerando-se as limitações desse estudo, apesar de os braquetes cerâmicos necessitarem de força de descolagem significativamente maior do que os braquetes metálicos, a tensão de descolagem foi limitada ao sítio de colagem, não afetando as fraturas de esmalte ao redor.

Comparison of the Enamel Surface Roughness from Different Polishing Methods: Scanning Electron Microscopy and Atomic Force Microscopy Investigation.

OBJECTIVE: This study aimed to compare the enamel surface roughness created by four polishing methods after debonding, by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). MATERIALS AND METHODS: Four experimental polishing groups (Sof-Lex disc, SD; sandblaster, SB; tungsten carbide bur, TB; and white stone bur, WB) and one control group were selected from 100 premolars (n = 20/group). The experimental teeth were bonded with a bracket, thermocycled, and debonded. Residual adhesive was removed by either of the respective methods. Pre and postdebonding root mean square (Rq) values were obtained from AFM evaluations. All specimens were examined and evaluated with SEM using a modified enamel surface index (modified ESI). STATISTICAL ANALYSIS: Differences among the polishing methods were compared with analysis of variance and Fisher's least significant difference test at p < 0.05. RESULTS: Both microscopic evaluations indicated that the surface with the greatest roughness herein belonged to the SD group, followed by that for SB, TB, and WB groups. AFM measurements indicated a maximum postdebonding Rq herein for the WB group and a significantly greater surface roughness for the TB and WB groups than for the SD and SB groups. Among the experimental groups, SEM followed by modified ESI evaluations revealed similar data to those obtained with AFM. Significant differences were seen among all paired groups, except for that between the SB and TB groups. CONCLUSION: Within the limitations of this study, all four polishing methods were concluded to be clinically acceptable for removing residual orthodontic adhesives.

Correlation of Bite Force Interpretation in Maximal Intercuspal Position among Patient, Clinician, and T-Scan III System.

OBJECTIVE: The main purpose of this article was to determine the correlation of bite force in maximal intercuspal position (MIP) among patient's perceptions, clinician subjective interpretation, and T-Scan III system. MATERIALS AND METHODS: Forty-three dental students at Naresuan University (Phitsanulok, Thailand) participated in the study. Subjects were positioned by Frankfurt horizontal plane paralleled to the horizontal plane and asked to bilaterally clenched in MIP. Patient's perception was evaluated by asking which side of the jaw had heavier bite force (right, left, or equally on both sides). Then, the clinician subjective interpretation was assessed using traditional occlusal indicators. Furthermore, patient's bite force was analyzed using T-Scan III. STATISTICAL ANALYSIS: Cohen's weighted kappa test was used to evaluate the correlation of bite force. RESULTS: The best correlation between patient's perception and T-Scan III was at the ± 7.5% cutoff range with 15 subject agreements. While the best correlation between clinician subjective interpretation and T-Scan III was at ± 5.0% cutoff range with 23 subject agreements. Cohen's weighted kappa indicated slight agreement between T-Scan III and patient's perception and fair agreement between T-Scan III and clinician. CONCLUSIONS: Clinician subjective interpretation is more clinically reliable than patient's perception when T-Scan III is used as a gold standard.