Evaluation of Stresses on Temporomandibular Joint in the Use of Class II and III Orthodontic Elastics: A Three-Dimensional Finite Element Study.

PURPOSE: The purpose of the present study was to evaluate the effects of the orthodontic elastic forces used in fixed orthodontic treatment on the temporomandibular joint (TMJ) with normal and anteriorly displaced discs. MATERIALS AND METHODS: Four different computer models for Class II and III malocclusion with the TMJ disc in the normal and anterior position were created. All the models were subjected to a constant force of 200g (125 N) on both sides to simulate the elastic pull force placed between the upper and lower jaw with 2 different configurations. Stresses on the TMJ were evaluated using finite element analysis. RESULTS: The stresses in both the condyle and the disc were greater in the Class II models than in the Class III models. Similar results were found between the groups according to the direction of the orthodontic elastics. In the Class II models, the peak value of the maximum principal stresses was located in the posterior region of the condyle in the models with disc in the normal position. CONCLUSIONS: The elastic forces used during fixed orthodontic treatment increases the stress on the TMJ, especially for Class II patients. If the disc is in an anterior position, the stresses could be more harmful to the retrodiscal tissue. Thus, during orthodontic treatment, the TMJ should be carefully assessed to avoid irreversible damage.

Clinical effect of a fluoride-releasing and rechargeable primer in reducing white spot lesions during orthodontic treatment.

INTRODUCTION: This study was performed to test the long-term efficacy of a highly filled resin primer (38%) that has superior fluoride release and recharge ability. METHODS: Sixty patients were divided into 2 groups. In group 1, adhesive-coated brackets (APC Plus Victory series, 3M Unitek, Monrovia, Calif) were bonded with a fluoride-releasing and rechargeable primer (Opal Seal; Ultradent, South Jordan, Utah). In group 2, the same adhesive-coated brackets were bonded with a conventional primer (Transbond XT Primer; 3M Unitek, Monrovia, Calif). In group 1, a blacklight source was used to examine the amount of adhesive remaining on enamel surfaces. This primer has a fluorescing agent and fluoresces under blacklight. If there was a lack of primer on any part of the enamel surrounding the brackets, new primer was added. Digital images of each tooth were taken to score and measure the area of white spot lesions (WSLs) after orthodontic treatment. DIAGNOdent (DIAGNOdent pen; KaVo Dental, Biberach, Germany) measurements were also used to assess WSLs after bracket removal. RESULTS: The WSL rate was 26.9% for group 1 and 29% for group 2. There was no significant difference between the WSL scores of the groups; however, a significant difference was observed in the DIAGNOdent measurements between the groups. According to area measurements of the lesions, there was no significant difference between the groups. CONCLUSIONS: The results of this long-term clinical study indicated that fluoride-releasing primer has no significant advantage in reducing demineralization over the control primer over the full orthodontic treatment period.

Clinical effectiveness of 2 orthodontic retainer wires on mandibular arch retention.

INTRODUCTION: The aim of this study was to evaluate and compare the clinical success of 2 lingual retainer wires. METHODS: The 120 patients included in the study were divided into 2 groups randomly. In group 1, 0.0175-in 6-strand stainless steel wire (Ortho Technology, Lutz, Fla) was used, the lingual retainers were fabricated on plaster models, and a silicon transfer key was used. In group 2, 0.0195-in dead-soft coaxial wire (Respond; Ormco, Orange, Calif) was used, and the lingual retainers were fabricated directly in the patient's mandibular arch without a study model. Pretreatment, posttreatment, and posttreatment 3-month, 6-month, 9-month, and 12-month 3-dimensional orthodontic models were evaluated. Failure rates, mandibular arch irregularity values, intercanine distances, and arch lengths were compared. RESULTS: The clinical bond failure rates were 13.2% for the 0.0175-in 6-strand stainless steel wire and 18.9% for the 0.0195-in dead-soft wire. The difference in bond failures between the 2 groups was not statistically significant. There was a statistically significant increase in mandibular arch irregularity in both groups during the 12-month follow-up. However, the increase was significantly higher in the second group than in the first one. Furthermore, the intercanine distance decreased over time in the second group. CONCLUSIONS: Our findings regarding mandibular arch measurements indicate that fabrication of lingual retainers can be more safely accomplished with 0.0175-in 6-strand stainless steel wire than with 0.0195-in dead-soft coaxial wire.

In-vitro bond strengths and clinical failure rates of metal brackets bonded with different light-emitting diode units and curing times.

INTRODUCTION: The purpose of this study was to compare the clinical failure rates and the in-vitro bond strengths of metal brackets bonded with different light-emitting diode (LED) devices and curing times. METHODS: Forty patients were included in the clinical part of this study. A split-mouth design was used, with the adhesive in group 1 cured for 10 seconds with an LED unit (Elipar S10; 3M Unitek, Monrovia, Calif), and the adhesive in group 2 cured for 3 seconds with another LED unit (VALO Ortho; Ultradent Products, South Jordan, Utah). Bond failures during 12 months of orthodontic treatment were recorded. In-vitro performance of the brackets was also compared by bonding brackets to extracted premolars and using the same light units and curing times (n = 20 for each group). The adhesive remnant index was used to determine the bond failure interface. RESULTS: Clinical bond failure rates were 2.90% for the Elipar and 3.16% for the VALO curing units. The difference in bracket failure rates between the 2 LED devices was not statistically significant. No statistically significant difference was found between the in-vitro bond strengths of the groups. CONCLUSIONS: Our findings regarding long-term clinical survival rates and in-vitro bond strengths indicate that bracket bonding can be safely accomplished in 10 seconds of light-curing with an Elipar LED and 3 seconds of light-curing with a VALO LED.

Effectiveness of surface polishing after debonding of metal brackets from different CAD-CAM materials.

PURPOSE: The purposes of this study were to compare and evaluate the surface texture of different restorative computer-aided design and computer-aided manufacturing (CAD/CAM) materials before bonding and after debonding of metal orthodontic brackets. MATERIALS AND METHODS: A total of 60 rectangular ceramic test specimens (n = 20 in each group) were prepared using feldspathic ceramic blocks (FLD; served as control), hybrid ceramic blocks (HC), and lithium disilicate ceramic blocks (LDC). Surface roughness (Ra) analysis was conducted using a profilometer before bonding the metal brackets. After the debonding and polishing procedures, a second surface roughness analysis was conducted on each specimen. The shear bond strength (SBS) test was applied to each specimen using a universal test machine for debonding the metal brackets. The debonded specimens were examined under a stereomicroscope and scored using a 4-step adhesive remnant index (ARI). The Ra and SBS values and the ARI scores were saved, and the data were analyzed statistically at a significance level of 0.05. One specimen from each group was examined under atomic force microscopy to visualize surface roughness. Furthermore, one specimen from each group was additionally prepared for scanning electron microscopy analysis. RESULTS: Statistically significant differences in SBS measurements were observed between all three groups. The highest SBS values were obtained from the FLD group, the lowest from the LDC group. The HC group showed significantly (P = 0.001) lower Ra values than the LDC and FLD groups after debonding and polishing. No significant differences were observed in the ARI scores between the groups. CONCLUSIONS: Hybrid ceramics could be a suitable alternative for fixed restorations in adult patients receiving subsequent treatments with fixed orthodontic appliances.

Effectiveness of an antibacterial primer used with adhesive-coated brackets on enamel demineralization around brackets: an in vivo study.

BACKGROUND: The aim of the study is to assess the clinical effect of an antibacterial monomer-containing primer on preventing white spot lesions (WSLs) during fixed orthodontic treatment. SUBJECT AND METHODS: The study included 35 patients. A split-mouth design was used during bonding of the brackets. In Clearfil (CF) group, adhesive-coated brackets (APC Plus Victory series, 3M Unitek, Monrovia, CA, USA) were bonded with an antibacterial monomer-containing primer (Clearfil Protect Bond, Kuraray Medical, Okayama, Japan). In Transbond (TB) group, the same adhesive-coated brackets were bonded using a conventional primer (Transbond XT Primer; 3M Unitek, Monrovia, CA, USA). The mean duration of orthodontic treatment was 16 months. Digital images of each tooth were used to assess the WSLs. The areas of the WSLs were measured with a software. The bond failures during orthodontic treatment were also recorded. RESULTS: After fixed orthodontic treatment, 23 of the 35 patients showed one or more WSLs. Of the total of 666 teeth, 114 WSLs occurred over the orthodontic treatment time. Rates of WSL in the CF and TB groups were 8.03% and 9.24%, respectively. The difference in WSL rates between the two groups was not statistically significant. No significant difference was observed in the lesion areas between the groups. Moreover, the difference in bracket failure rates between the two groups was also not statistically significant. CONCLUSION: The results of this long-term clinical study indicated no significant difference between the antibacterial monomer-containing primer group and the control group in the efficacy of reducing demineralization throughout the orthodontic treatment.

Are age and radiographic features effective on orthodontic alignment of palatally impacted maxillary canines? a retrospective study.

PURPOSE: The purpose of the study was to evaluate the effects of age and radiographic parameters on success of orthodontic alignment of impacted maxillary canines. MATERIALS AND METHODS: The retrospective records of 50 patients (mean age 20.44 years) who had impacted maxillary canines in palatal position were included. The patients was requiring surgical exposure and mechanical orthodontic treatment were divided into two groups as adolescent (age≤18; n=24) and adult (age>18; n=26). In both groups, the treatment time and success were evaluated clinically and radiographically. RESULTS: Fifty patients between the ages of 13 to 42 (12 males and 38 females) with palatally impacted canines were treated with combined surgical-orthodontic approach. Forty-seven teeth (94%) had reacted to surgical exposure and orthodontic alignment within 16 to 36 months with a mean of 24.81 months. Three of the impacted canines (6%) were surgically removed because no movement was observed following 10 months of traction forces. CONCLUSION: The distance of the canine tip to the occlusal plane on the lateral cephalometric radiographs have found to be related with the total orthodontic treatment time. Neither the age of the patient nor other clinic and radiographic parameters had influence on the treatment results of alignment of maxillary canines following surgical exposure.

In vivo effect of antibacterial and fluoride-releasing adhesives on enamel demineralization around brackets: A micro-CT study.

OBJECTIVES: The aim of this in vivo study was to investigate the preventive effect of two different adhesives on enamel demineralization and compare these adhesives with a conventional one. MATERIALS AND METHODS: Fifteen patients requiring the extraction of their first four premolars for orthodontic treatment were included in the study. One premolar was randomly selected, and an antibacterial monomer-containing and fluoride-releasing adhesive (Clearfil Protect Bond, Kuraray Medical, Okayama, Japan) was used for orthodontic bracket bonding. Another premolar was randomly selected, and a fluoride-releasing and recharging orthodontic adhesive (Opal Seal, Ultradent Products, South Jordan, Utah) was used. One premolar was assigned as a control, and a conventional adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) was used. The teeth were extracted after 8 weeks, and the demineralization areas of the 45 extracted teeth were analyzed using microcomputed tomography with software. RESULTS: There was no significant difference between the white spot lesion (WSL) rates of the adhesives (P > .05). The volumes of the WSLs varied from 0 to 0.019349 mm3. Although Opal Seal showed the smallest lesion volumes, there was no significant difference in volumetric measurements of the lesions among the groups (P > .05). CONCLUSIONS: The findings indicated no significant differences between the preventive effects of the adhesives used in this in vivo study over 8 weeks.

Smile Attractiveness: Differences among the Perceptions of Dental Professionals and Laypersons.

OBJECTIVE: The aim of this study was to analyze the acceptable values of female and male smile attractiveness based on different amounts of gingival display and buccal corridor widths, as judged by dental professionals and laypersons. METHODS: The frontal smile photographs of a male and female model were modified to create seven different smile photographs of the same individual with different amounts of gingival display and buccal corridor widths. Overall, 249 evaluators in four groups (Group 1=orthodontists, Group 2=prosthodontists, Group 3=oral surgeons, and Group 4=laypersons) evaluated 28 images of different smiles with a visual analogue scale. Significant statistical differences were found among the evaluator's scores (p<0.05). RESULTS: For female smiles, the highest scores were obtained for 12% and 0% buccal corridor width. For male smiles, the highest scores were obtained for 4%, 0%, 12%, and 16% buccal corridor width for Groups 1, 2, 3, and 4 respectively. The highest scores were obtained for +2 mm and -3 mm of gingival display for female smiles. CONCLUSION: The amount of gingival display, the buccal corridor width, and the knowledge in the field affects the perceptions of smile attractiveness. Thus, 3 mm of gingival display and buccal corridor width larger than 16% should be avoided for esthetic reasons during dental treatment.

Maxillary sinus volume in patients with impacted canines.

OBJECTIVES: To evaluate the maxillary sinus volumes in unilaterally impacted canine patients and to compare the volumetric changes that occur after the eruption of canines to the dental arch using cone beam computed tomography (CBCT). MATERIALS AND METHODS: Pre- (T0) and posttreatment (T1) CBCT records of 30 patients were used to calculate maxillary sinus volumes between the impacted and erupted canine sides. The InVivoDental 5.0 program was used to measure the volume of the maxillary sinuses. The distance from impacted canine cusp tip to the target point on the palatal plane was also measured. RESULTS: Right maxillary sinus volume was statistically significantly smaller compared to that of the left maxillary sinus when the canine was impacted on the right side at T0. According to the T1 measurements there was no significant difference between the mean volumes of the impaction side and the contralateral side. The distance from the canine tip to its target point on the palatal plane were 17.17 mm, and the distance from the tip to the target point was 15.14 mm for the left- and right-side impacted canines, respectively, and there was a significant difference between the mean amount of change of both sides of maxillary sinuses after treatment of impacted canines. CONCLUSIONS: Orthodontic treatment of impacted canines created a significant increase in maxillary sinus volume when the impacted canines were closer with respect to the maxillary sinus.