Effects of Different Remineralisation Agents and Adhesives Around Orthodontic Brackets: Is There a Relationship Between Remineralisation and Shear Bond Strength?

PURPOSE: The aim of this in-vitro study was to evaluate the effects of different remineralisation agents and adhesives on the remineralisation of white spot lesions (WSL) using quantitative light-induced fluorescence (QLF) and the shear bond strength (SBS) of brackets. MATERIALS AND METHODS: One hundred fifty premolars were bonded with Transbond XT and resin-modified glass-ionomer cement (RMGIC). WSL were created using a demineralization solution and an APF gel, Tooth Mousse (TM) and Duraphat were applied for remineralisation. WSL were evaluated using QLF and SBS of brackets and tested using an Instron testing machine. Paired-samples t-test, independent-samples t-test and one-way ANOVA were used for comparisons of the ∆F, area and SBS. Post-hoc tests were performed using Tukey's test. RESULTS: In the Transbond group, all remineralisation agents provided remineralisation, with Duraphat producing greater improvement. In terms of lesion area, the positive control and APF gel group values were close to each other, and a statistically significant improvement was observed in the TM and Duraphat groups' areas. In the RMGIC group, with TM application, the ΔF value was statistically significantly higher; area differences between the APF and TM groups were not statistically significant. The Transbond group showed greater SBS than did RMGIC, and in the Transbond group, Duraphat had the highest SBS value. CONCLUSIONS: In bonding with Transbond, the Duraphat group demonstrated greater improvement than other remineralisation agents. In the RMGIC group, the best remineralisation was obtained by TM. The Transbond XT and Duraphat combination provided the highest SBS values.

Effects of High-Energy Curing Lights on Time-Dependent Temperature Changes of Pulp Space During Orthodontic Bonding.

OBJECTIVE: The purpose of this study was to assess the temperature changes and cooling times during orthodontic bonding by a light-emitting diode (LED) and plasma arc lights (PAC) in different time and power modes with thermal imaging. METHODS: A total of 100 human permanent upper first premolar teeth were included in the study. Five groups were conducted, 20 teeth each, and different energy outputs of curing lights were used for adhesive polymerization with different exposure times. The temperature changes in the pulp space and cooldown times were measured by a thermal imaging system. A paired t-test, analysis of variance (ANOVA), and Student-Newman-Keuls multiple comparison tests were used for data analysis. RESULTS: A statistically significant temperature rise was detected with all curing lights (p<0.05). The greatest temperature changes were observed in the LED standard mode with 10 seconds of exposure time (6.66±1.98°C) and LED extra power mode with 6 seconds of exposure time (6.50±1.64°C) among groups, while using PAC for 3 seconds created the smallest temperature increase (1.81±0.99°C). An application of the LED extra power mode for 6 seconds exhibited the longest cooldown time (205.91±47.48 seconds), and the shortest cooldown time was detected as 71.30±43.15 seconds with the PAC 3-second application. CONCLUSIONS: LED lights with an increased exposure time induced significant temperature rises, while no PAC light group exceeded the critical threshold value. The exposure time is more important than the energy output level of the light-curing system on temperature increments of the pulp chamber.

The Effect of Bimaxillary Surgery on the Airway Morphology in Class III Patients: Taking Into Account the Head Posture During Walking.

OBJECTIVES: To assess changes in head and neck posture, airway, hyoid, tongue, and soft palate in skeletal class III individuals whose cephalograms were taken using dynamic natural head positioning method with an inclinometer. MATERIALS AND METHODS: This study was conducted on 20 class III patients operated with double jaw surgery. Natural head positions were determined before and 6 months after the surgery. Craniocervical, pharyngeal airway, tongue, and hyoid positions were measured. In the analysis of the data, paired t test, independent sample t test and correlation tests were used. RESULTS: There was a statistically significant change in the craniocervical measurements with the operation and the head position was further extended (P < 0.05). Significant changes were observed in the soft palate angles upon surgery (P < 0.026) and the increase in oropharyngeal airway area was statistically significant (P < 0.001). There was a statistically significant increase in tongue length (TL) and distance from vertical reference plane to tongue tip (TTi/VRP) measurements (P < 0.001 and P < 0.012, respectively). There was a statistically significant decrease in distance from horizontal reference plane to tongue tip (TTi/HRP) and tongue dorsum (TD/HRP) measurements (P < 0.033 and P < 0.003, respectively). The only significant change among the hyoid bone position-related measurements was distance between hyoidale and epiglottis (P < 0.013). CONCLUSIONS: Hyoid bone location, tongue measurements, and posterior pharyngeal airway were found to be related to each other and they have been found to be effective on the head and neck posture. Head position will be affected by possible surgical alternatives.

Effectiveness of incremental vs maximum bite advancement during Herbst appliance therapy in late adolescent and young adult patients.

INTRODUCTION: The purpose of this research was to compare the effects of Herbst appliance therapy using incremental vs maximum advancement in late adolescent and young adult patients with Class II skeletal malocclusion. METHODS: Forty-two patients with skeletal Class II malocclusion were treated with cast-splint Herbst appliances. The subjects were randomly allocated into 2 groups according to activation type: incremental advancement (IA) and maximum advancement (MA). Initial forward movement in the IA group was 4 to 5 mm and was followed by subsequent bimonthly advancements of 2 mm. Single-step advancement was achieved in the MA group until an edge-to-edge incisor relationship or an overcorrected Class I molar relationship was obtained. Total treatment times were 9.7 ± 1.1 months for the IA group and 9.5 ± 1.1 months for the MA group. Dental, skeletal, and soft tissue measurements were performed on lateral cephalograms taken just before and at the end of the Herbst appliance therapy. Statistical significance was set at P ≤ 0.05. RESULTS: All mandibular skeletal dimensions increased, and improvements of the sagittal maxillomandibular parameters were found in both groups. Protrusion and proclination of the mandibular incisors were greater in the IA group (95.90° ± 5.34°) compared with the MA group (92.04° ± 7.92°). Other dentoalveolar changes in both groups were intrusion of the maxillary first molars, and extrusion of the mandibular first molars and maxillary incisors. The mentolabial sulcus was flattened, soft tissue convexity was reduced, and forward movement of mandibular soft tissues was seen after Herbst therapy. CONCLUSIONS: Similar skeletal, dental, and soft tissue changes were obtained in both groups after Herbst therapy. Greater proclination and more protrusion of the mandibular incisors were found in the IA group.

The effects of different desensitizer agents on shear bond strength of orthodontic brackets after home bleaching: an in vitro study.

PURPOSE: The aim of this study was to test the null hypothesis that no difference exists between shear bond strength values of control and bleaching plus desensitizer applied groups. MATERIALS AND METHODS: A hundred freshly extracted human premolar teeth were randomly divided into five groups. Group I served as the control group with no bleaching application, while only bleaching was achieved in Group II. Desensitizer containing potassium nitrate-fluoride and casein phosphopeptide amorphous calcium phosphate were applied in Groups III and IV, after bleaching respectively. A bleaching agent containing amorphous calcium phosphate was used in Group V. Shear bond strength tests were carried out using a universal testing machine (Instron Corp., Norwood, MA, USA). Remnant adhesive on the teeth and brackets was examined to score the adhesive remnant index. Kruskal-Wallis and Chi-Square tests were used for statistical analysis of the data. RESULTS: Statistically significant differences were found among the groups for shear bond strength values (p<.001). The shear bond strength of Group III (8.0±2.2 MPa) was significantly lower than the other groups (p<.05). The highest shear bond strength values were found for Group I (13.6±3.7 MPa) and Group IV (12.8±4.0 MPa). No statistically significant difference was observed between Group II (10.0±2.7 MPa) and Group V (10.8±2.9 MPa). The differences between adhesive remnant index scores of the groups were not statistically significant. CONCLUSION: Casein phosphopeptide amorphous calcium phosphate gel application showed a similar shear bond strength value to the control group, while shear bond strength values decreased after using other desensitizers.

Effects of cell-mediated osteoprotegerin gene transfer and mesenchymal stem cell applications on orthodontically induced root resorption of rat teeth.

Aim: The aim of this study is to evaluate and compare therapeutic effects of mesenchymal stem cell (MSCs) and osteoprotegerin (OPG) gene transfer applications on inhibition and/or repair of orthodontically induced inflammatory root resorption (OIIRR). Materials and methods: Thirty Wistar rats were divided into four groups as untreated group (negative control), treated with orthodontic appliance group (positive control), MSCs injection group, and OPG transfected MSCs [gene therapy (GT) group]. About 100g of orthodontic force was applied to upper first molar teeth of rats for 14 days. MSCs and transfected MSC injections were performed at 1st, 6th, and 11th days to the MSC and GT group rats. At the end of experiment, upper first molar teeth were prepared for genetical, scanning electron microscopy (SEM), fluorescent microscopy, and haematoxylin eosin-tartrate resistant acid phosphatase staining histological analyses. Number of total cells, number of osteoclastic cells, number of resorption lacunae, resorption area ratio, SEM resorption ratio, OPG, RANKL, Cox-2 gene expression levels at the periodontal ligament (PDL) were calculated. Paired t-test, Kruskal-Wallis, and chi-square tests were performed. Results: Transferred MSCs showed marked fluorescence in PDL. The results revealed that number of osteoclastic cells, resorption lacunae, resorption area ratio, RANKL, and Cox-2 were reduced after single MSC injections significantly (P < 0.05). GT group showed the lowest number of osteoclastic cells (P < 0.01), number of resorption lacunae, resorption area ratio, and highest OPG expression (P < 0.001). Conclusions: Taken together all these results, MSCs and GT showed marked inhibition and/or repair effects on OIIRR during orthodontic treatment on rats.