Selim Arici

Mandibular Asymmetry in Different Occlusion Patterns

OBJECTIVE To investigate the effects of different occlusion types on the mandibular asymmetry in young individuals. MATERIALS AND METHODS Mandibular asymmetry measurements were performed on the panoramic radiographs of 189 subjects (104 females and 85 males; age range, 11-15 years), with different occlusion patterns. The subjects were divided into five groups according to the occlusion types, namely, Angle Class I (Cl I), Class II division 1 (Cl II/1), Class II division 2 (Cl II/2), Class III (Cl III), and normal occlusions. The Kruskal-Wallis test was used to determine the possible statistically significant differences between the groups for condyle, ramus, and condyle-plus-ramus asymmetry index measurements. Identified differences between groups were further analyzed using the Mann-Whitney U-test at the 95% confidence interval (P<.05). RESULTS There were no statistically significant differences between male and female subjects. The Kruskal-Wallis test showed that the occlusion type had a significant effect on the condylar asymmetry. In Cl II/1 cases, condylar asymmetry values were significantly different from the values of Cl II/2 and Cl III malocclusion and normal occlusion types. The normal occlusion control group was significantly different from those of Cl II/1 and the Cl I malocclusion groups. CONCLUSION Cl II/1 malocclusion has a significant effect on the condylar asymmetry index when compared to Cl II/2 and Cl III malocclusion and normal occlusion types. However, the mean condylar asymmetry index value in Cl II/1 malocclusion was not different from Cl I malocclusion.

Effects of first molar extraction on third molar angulation and eruption space

OBJECTIVES The aim was to investigate the effects of orthodontic treatment with 4 first molar extractions on the angulations and eruption spaces of all third molars and to compare these changes with outcomes of nonextraction samples used as a control group. STUDY DESIGN This study was carried out on standardized panoramic radiographs of 41 subjects (8 male, 33 female) with a mean age of 16.6 years (range 13 to 20 years). Twenty-one of the subjects were orthodontically treated with extraction of the 4 first permanent molars, and 20 had nonextraction treatment. The angulational changes and eruption spaces of third molars were evaluated on the panoramic radiographs taken before treatment and at the end of the observation period. RESULTS Analysis of the linear variables demonstrated a statistically significant difference between the 2 groups for all third molar eruption spaces (P < .001). The mean differences in the third molar eruption spaces between the pretreatment and posttreatment values for the first molar extraction group were higher than those of the nonextraction cases. CONCLUSION Orthodontic treatment accomplished with extractions of the permanent first molars increases the eruption spaces of third molars and decreases their impaction. In addition, it has greater favorable effect on the angulation of the upper third molars than of the lower third molars.

Effects of thermocycling on the bond strength of a resin-modified glass ionomer cement: an in vitro comparative study.

This study investigated the effects of thermally induced stresses (thermocycling) on the shear bond strength of resin-modified, chemically cured, glass ionomer cement for use as an orthodontic bonding agent. A conventional no-mix composite resin was also used as a control. Mesh-based metal orthodontic brackets were bonded to extracted human premolars using either the resin-modified glass ionomer cement or the no-mix composite resin. Specimens were stored either in water at 37 degrees C for 24 hours for baseline data or thermocycled between 5 degrees C and 55 degrees C for 200 and 20,000 cycles before testing the in vitro shear bond strengths. Thermocycling reduced shear bond strengths for all specimens. The resin-modified glass ionomer cement showed a 11.1% decrease after 200 thermocycles and 26.5% decrease after 20,000 thermocycles, whereas the no-mix adhesive resin showed only 5.7% and 17.9% reductions, respectively. Analysis of variance showed statistically significant differences between the mean shear bond strengths of the groups at the P < .001 level of significance. For the resin-modified glass ionomer cement groups, the predominant bond failure site was at the bracket-adhesive interface. The results of this study suggest strongly that resin-modified glass ionomer cements offer a viable alternative to conventional no-mix composite resins, with satisfactory in vitro shear bond strength even after 20,000 thermocycles.

Effects of fixed functional appliance treatment on the temporomandibular joint

INTRODUCTION In this study, we tested the hypothesis that fixed functional appliance treatment in a group of Class II Division 1 patients with mandibular retrusion changes the condyle position in the glenoid fossa. METHODS Transverse computed tomography images were taken of the temporomandibular joint region in 60 children with Class II Division 1 malocclusion. Thirty randomly selected patients were treated with a fixed functional orthodontic appliance (Forsus nitinol flat-spring, 3M Unitek Corp, Monrovia, Calif) for 7 months; another 30 patients without treatment were used as controls. Computed tomography images taken at the beginning and end of fixed functional appliance treatment were used for estimating the condyle-glenoid fossa relationship, including the volumes of condyle, glenoid fossa, and anterior and posterior joint spaces. RESULTS Although the volumes of the condyle and glenoid fossa increased more in the study group than in the control group, the differences were not statistically significant. However, statistically significant differences were found between the groups in the volumes of the anterior and posterior joint spaces (P < 0.05). CONCLUSIONS When the volumes of the anterior and posterior joint spaces changed, the condyle was more posteriorly positioned in the glenoid fossa in the study group than in the control group.

The clinical and laboratory effects of bracket type during canine distalization with sliding mechanics

OBJECTIVE To compare the extent of canine movement with sliding mechanics between a self-ligating (SC) bracket and a modified twin design (MT) bracket. To test the in vitro coefficient of friction (COFs) of these two metal brackets on 0.019- × 0.025-inch, stainless-steel arch wires. MATERIALS AND METHODS For the clinical portion of this study, a split-mouth design was used to bond the brackets of 19 patients. Canine distalization was achieved on a 0.019- × 0.025-inch, stainless-steel arch wire with a nickel-titanium, closed-coil spring strained between a mini-screw and a canine bracket. The linear and angular measurements were performed using lateral cephalometric radiographs taken before and after canine distalization. A tribometer was also used to measure the COFs of the bracket types in vitro. For comparisons, Students t-tests for paired and unpaired samples were used at the 95% confidence level. RESULTS The extent of canine movement and the changes in the canine and molar teeth angles were not significantly different between the SC and MT brackets. After 8 weeks, the mean canine movements were 1.83 and 1.89 mm in the maxilla and 1.79 mm and 1.70 mm in the mandible with the SC and MT brackets, respectively. The mean COF of the MT brackets (0.21) was significantly lower than that of the SC brackets (0.37) during in vitro testing. CONCLUSION It is suggested that the rate of canine distalization was not different between the two groups, although in vitro COFs of the SC bracket was higher.

Adhesive thickness effects on the bond strength of a light-cured resin-modified glass ionomer cement.

These in vitro studies investigated the effect of adhesive thickness on the tensile and shear bond strength of a light-cured, resin-modified glass-ionomer cement (FO). A light-cured conventional composite resin (CO) was used as the control material. Mesh-based metal brackets were bonded to extracted human premolars using FO and CO. The adhesive thickness was controlled by a special device and 0, 0.25, and 0.5 mm thicknesses were tested for both bonding agents. All bonded specimens were stored in distilled water at 37 degrees C for 48 hours and thermocycled between 5 degrees C and 55 degrees C for 200 cycles before testing. Analysis of variance showed that bond strength was significantly affected by the adhesive thickness (P < .001) and type of adhesive (P = .001). There were statistically significant differences between the mean bond strengths of the groups at the P < .05 level of significance. For all adhesive thicknesses, CO had higher bond strength values than those of FO in both test modes. The bond strength values were also analyzed using a Weibull analysis, which showed the most favorable adhesive thickness, and the 5% and 90% probabilities of failures was 0.25 mm in the FO groups. Bracket-adhesive interface failure was predominant for all groups in tensile testing, but enamel-adhesive interface failures increased with increased adhesive thickness in shear testing for the FO. This study suggests that adhesive thickness under a bracket could be particularly important when using a FO in direct bonding.

Sandblasted Metal Brackets Bonded with Resin-modified Glass Ionomer Cement In Vivo

The aim of this in vivo study was to evaluate the effects of sandblasting metal brackets on their clinical performance when resin-modified, chemically cured glass ionomer cement was used for bonding. A total of 60 patients with a range of malocclusions were allocated randomly into two groups. For the first 30 cases, teeth were divided into quadrants so that sandblasted, mesh-based metal brackets (SB) were bonded directly to the upper left and lower right quadrants using the resin-modified glass ionomer cement. The mesh-based (no sandblasting) brackets bonded to the other quadrants with the same adhesive were used as control (CO). A split-mouth design was used, and the allocation of the brackets per quadrant was reversed for the second 30 cases. Sandblasting of the bracket bases was accomplished using 25-microm aluminum oxide particles for three seconds. The manufacturers instructions were followed for bonding. The number, site, and date of first-time bracket failures were monitored throughout active orthodontic treatment, and the observation time was 20 months. The bond failure rates were 4.9% and 4.3% for the SB and CO brackets, respectively. No statistically significant difference was found between the groups for failure rates. The bond failure sites were predominantly at the enamel-adhesive interface in both groups. Sandblasting did not have a positive effect on the clinical performance of the mesh-based metal brackets when bonded with resin-modified glass ionomer cement.

Nonextraction Treatment with Rapid Maxillary Expansion and Mandibular Symphyseal Distraction Osteogenesis and Vertical Skeletal Dimensions

OBJECTIVE To investigate the effects of rapid maxillary expansion (RME) and mandibular symphyseal distraction osteogenesis (MSDO) on vertical dimensions of the face. MATERIALS AND METHODS Fourteen patients, nine girls and five boys, underwent RME and MSDO procedures. Distraction was carried out at a rate of 1 mm per 24 hours with a tooth-borne appliance. The amount of distraction was 7 mm for each patient. Standardized lateral cephalograms were taken at the following time periods: before treatment (T0), after RME (T1), at the completion of MSDO (T2), and at the end of fixed orthodontic treatment (T3). The data were evaluated by using a general linear model of repeated-measures analysis of variance and paired t-tests at the 95% confidence level. RESULTS RME significantly increased the vertical dimensions of the face and decreased the overbite (P < .001). Although the vertical parameters of the face on the lateral cephalogram decreased after MSDO, these decreasing effects were statistically insignificant just for the distances measured from the horizontal reference line to the chin points. In other words, MSDO decreased the vertical skeletal dimensions that were increased by RME, but this neutralizing effect of MSDO was not as much as the increase caused by RME. CONCLUSION Treatment modalities (RME, MSDO, and fixed orthodontic treatment) described in this study, in total, had little effect on the vertical skeletal measurements of the face.

A prospective randomised cross-over study of the effect of local haemostasis after third molar surgery on facial swelling: an exploratory trial

Objective This study was undertaken in order to evaluate the effects of local haemostasis on the facial swelling induced in patients undergoing surgical removal of impacted mandibular third molar teeth.Design A prospective randomised cross-over study.Setting Department of Oral and Maxillofacial Surgery, Samsun, Turkey, 2002.Materials and methods Twenty-five healthy patients who were having bilaterally symmetric, impacted third molar extraction were studied. The teeth were removed in two separate operations by two surgeons who had equal academic degrees. The patients were assigned to test and control groups by random selection. One side served as control and on the other local haemostasis was achieved by a haemostatic agent (oxidised regenerated cellulose). This was placed into the socket following gauze packing for 3 minutes (test). The operating time therefore significantly increased in the test group. Data was collected regarding the operating time, mouth opening and facial swelling.Results There were no statistically significant differences between the test and control groups for the mean values of the facial swelling and mouth opening at day 1 and 3 post-operatively (P > 0.05). Operating time was statistically longer for the test group than the control (P < 0.001).Conclusion This study has shown that establishment of local haemostasis after removal of impacted mandibular third molars is not so effective in preventing facial swelling.

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.