Effectiveness of medical coating materials in decreasing friction between orthodontic brackets and archwires.

OBJECTIVE: The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al2O3), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. METHODS: Stainless steel canine brackets, 0.016-inch round nickel-titanium archwires, and 0.019 × 0.025-inch stainless steel archwires were coated with Al2O3, TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. RESULTS: Coating of the metal bracket as well as nickel-titanium archwire with Al2O3 reduced the coefficients of friction (CoFs) for the bracket-archwire combination (p < 0.01). When the bracket and stainless steel archwire were coated with Al2O3 and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket-archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al2O3 coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. CONCLUSIONS: Our findings suggest that the CoFs for metal bracket-archwire combinations used in orthodontic treatment can be decreased by coating with Al2O3 and TiN thin films.

Dose-related effects of extracorporeal shock waves on orthodontic tooth movement in rabbits.

The purpose of this animal study is to investigate the quantitative effects of extracorporeal shock waves applied at two different impulses and with two different applicators on orthodontic tooth movement. Thirty-five New Zealand rabbits were randomly divided into five groups (n = 7): the four experimental extracorporeal shock wave groups-focused/500 impulses, focused/1000 impulses, unfocused/500 impulses, and unfocused/1000 impulses-and the control group. Orthodontic tooth movement was achieved by application of reciprocal force between two maxillary incisors. In the experimental groups, animals received 500 or 1000 impulses of extracorporeal shock waves at 0.19 mJ/mm2 with focused or unfocused applicators depending on the group to which they belonged. These experiments were conducted on days 0, 7, and 14. Orthodontic tooth movement was measured with 0.01 mm accuracy at one-week intervals. On days 7 and 21, the bone-specific alkaline phosphatase levels were measured from blood samples. After 21 days, the animals were sacrificed and the area between the two maxillary incisors was stereologically examined. Orthodontic tooth movement in the focused/500 impulses and focused/1000 impulses groups was significantly increased compared to the control group. A significant difference in bone-specific alkaline phosphatase levels between the unfocused/500 impulses and control groups was found at 21st day. Stereological analysis showed that there were significant increases of the formation of new bone, connective tissue, and vessels in the experimental groups. The application of extracorporeal shock waves, especially with a focused applicator, could accelerate orthodontic tooth movement.

Buccolingual Inclination Effects of Self-Ligating and Conventional Premolar Brackets: A Cone Beam Computed Tomography Study.

OBJECTIVE: This study aimed to compare the effects of passive self-ligating (PSL) and conventional ligating (CL) of brackets on the buccolingual inclination (BLINC) of the maxillary premolars. METHODS: This in vitro study included a PSL bracket group and a CL bracket group. Acrylic teeth on typodonts were aligned using 0.014-inch heat-activated nickel titanium (HANT) (T1) and 0.019×0.025-inch HANT (T2) and 0.021×0.025-inch stainless steel (SS) (T3) archwires in a sequence. Standardized cone beam computed tomography (CBCT) images were taken immediately after each archwire stage. The differences of premolar teeth BLINC values in the 0.019×0.025-inch and 0.014-inch HANT archwires (T2-T1) and 0.021×0.025-inch SS and 0.019×0.025-inch HANT archwires (T3-T2) were compared between PSL and CL groups. The value of p < 0.05 was considered statistically significant. RESULTS: The BLINC change of the second premolar (SPM) showed a statistically significant difference (p=0.008), but the BLINC change of the first premolar (FPM) (p=0.056) between the groups showed no statistically significant difference during the T2-T1 stage. However, there were statistically significant differences between two groups in the BLINC of the FPM (p=0.032) and SPM (p=0.032) in the T3-T2 stage. The angular changes in the buccal direction in the PSL group were higher than those in the CL group. CONCLUSION: The PSL upper premolar brackets used with the 0.021×0.025-inch SS archwire produced more buccal crown movement of the upper PM teeth compared with that of the CL brackets.

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 effects of flapless osteopuncture-facilitated tooth movement in the maxilla and the mandible.

BACKGROUND: This study aimed to investigate the effects of a minimally invasive, flapless procedure to enhance tooth movement in both jaws and to determine whether this triggers the acceleration when repeated monthly. MATERIAL AND METHODS: The sample consisted of thirty-two individuals whose orthodontic treatment required canine retraction. They were divided into an experimental group and control group. Osteopunctures were performed using orthodontic mini-screws at the distal aspects of the canine teeth at the beginning and on the fourth week of distalization in the experimental group. The control group was treated with conventional mechanics. All canines were retracted. The rates of canine distalization, rotation, and tipping were measured on the first, fourth, and eighth weeks of distalization. First molar anchorage loss was also measured. Intergroup and intragroup analyses were performed. RESULTS: Flapless osteopuncture-facilitated tooth movement resulted in greater canine distalization and reduced molar movement in the maxilla in the experimental than in the control group during the first month of distalization. In addition, the extent of upper canine movement was significantly higher in the experimental group in the first month than in the second. No differences in canine and molar movement in the mandible were observed between the two groups. CONCLUSIONS: OP, as applied in this study, is an effective method for increasing the rate of tooth movement in the maxilla. Repeating the procedure monthly does not appear to show a major advance of tooth movement. Key words:Accelerated tooth movement, flapless osteopuncture.

The Radiological and Stereological Analysis of the Effect of Low-Level Laser Therapy on the Mandibular Midline Distraction Osteogenesis.

OBJECTIVE: The aim of this study was to evaluate the effect of low level laser therapy (LLLT) on bone mineral density by using high-resolution computerized tomography (HR-CT) and stereology in patients subjected to mandibular midline distraction. METHODS: Nine patients between the ages of 13 and 16 years with mandibular transverse deficiency (>5 mm) were evaluated. Mandibular midline distraction osteogenesis was performed for all the patients. The patients were divided into 2 groups: the control group (n = 4) and the laser group (n = 5). GaAlAs, 830 nm wavelength, power of 40 mW, energy of 8.4 J/cm2 dose per spot, was directly applied from 2 points on the mandibular midline. The laser was applied in 8 treatment sessions at 48-hour intervals. Bone mineral density and volume of the newly formed bone were analyzed using HR-CT and stereological methods. RESULTS: A higher bone mineral density rate was found in the laser group (P < 0.05). A higher newly formed immature bone rate was found in the control group (P < 0.001). These findings suggest that more mature bone may also have a greater mineral organization than that of immature newly formed bone, which is shown by HR-CT and stereological results. CONCLUSIONS: The retention period can be shortened and mineralization may be increased by using LLLT in mandibular distraction osteogenesis.

Comparison of the frictional characteristics of aesthetic orthodontic brackets measured using a modified in vitro technique.

OBJECTIVE: The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. METHODS: Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 × 0.025-in wire in the 0.018-in slots and a 0.019 × 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (α = 0.05) were also used for statistical analyses. RESULTS: There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (µ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (µ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (µ = 0.85). CONCLUSIONS: Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

Multidisciplinary management of a fused tooth: a case report.

Objective. Fusion is a dental anomaly that arises through the union of two adjacent teeth. The case report presents multidisciplinary management of a fused maxillary anterior tooth. Case Report. A 10-year-old boy was referred to the pediatric dental clinic with the chief complaint of a large upper anterior tooth. Intraoral and radiographic examinations indicated fusion between the permanent maxillary right central incisor and a supernumerary tooth. According to the treatment plan, the fused tooth was sectioned, and the mesial portion was removed. The remaining tooth section was restored with composite resin, and the diastema between the central incisors was closed with orthodontic treatment. After an 18-month followup period, the tooth showed no sign of pathosis. Conclusion. The technique described here offers a simple and effective method for restoring a fused tooth that reestablishes function, shape, and esthetics.

An evaluation of factors associated with persistent primary teeth.

The aim of the present study was to investigate the reasons for the persistence of primary teeth and also use panoramic radiography to determine the characteristics of persistence teeth. Four-hundred and twenty-six panoramic radiographies, which diagnosed one or more retained primary teeth, were selected from 100,577 panoramic radiographic image files from nine clinics and six different cities in Turkey. The selected radiographies were evaluated to determine the reasons for the persistence of primary teeth; furthermore, this study analyzed the characteristics of the retained primary teeth including tooth type, number, location, and root resorption, and whether, or not, the primary teeth showed evidence of pathological conditions, such as periodontal problems, caries, ankylosis, infra-occlusions, or tipping of the adjacent permanent teeth. Six hundred and seventy-seven retained primary teeth were determined in 426 patients (148 males and 278 females). Retained primary teeth were found most frequently in the mandible rather than the maxilla and the left side was more frequently affected than the right side. Level 1 was found as a most frequently encountered root resorption level. Within the limitation of the present study, the most common type of persistent primary teeth seen on the dental arch were mandibular primary second molars, followed by maxillary primary canines. The most frequent reason for the persistence was the congenital absence of successors to the primary teeth, followed by impaction of the successor teeth.

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, Student's 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.

Retrospective analysis of impacted first and second permanent molars in the Turkish population: a multicenter study.

OBJECTIVES: The purpose of the present study was to retrospectively analyze 170 case series of patients with 200 impacted first and second permanent molars. STUDY DESIGN: Records of 104.408 patients were retrospectively screened in this multicenter study. The chosen study population consists of 170 patients who presented with impacted or retained first and second permanent molar. All patients with impacted first or second permanent molar had undergone clinical and radiographic examinations. The following factors were analyzed: age and gender, frequency, distribution, location, position, the number of impacted tooth, primary and secondary retention, degree of infraocclusion, associated pathologic conditions and treatment method. RESULTS: There were a total of 170 patients (male: 91, female: 79, mean ages 22.69 ± 8.99 years ranging from 13 to 66 years of age) with 200 retained or impacted permanent molars in 104.408 patients. In this study, 200 impacted teeth which were analyzed were 125 molars (62.5%) vertical position, 17 (8.5%) horizontal, 38 (19%) mesioangular, 12 (6%) distoangular, and 7 (3.5%) buccolingual inclination There were 52 primarily retained (26%) and 32 secondarily retained (16%) molars. 137 (68.5%) molars were asymptomatic. Cystic formation was present in 13 (6.5%) cases. CONCLUSIONS: Although the impactions of first and second permanent molars do not occur frequently, it is important to make an early diagnosis in order to start treatment at the optimal time.

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.

Comparison of different toothbrushing protocols in poor-toothbrushing orthodontic patients.

The aim of this study was to determine, using a computerized image analysing system, whether the use of a curved-bristle toothbrush (CBT) alone is more effective than two other toothbrushing protocols on dental plaque elimination in poor-toothbrushing orthodontic patients. The labial surfaces of the maxillary canine-to-canine anterior teeth of 30 patients (12 males and 18 females) were individually photographed following dental plaque staining before and 4 weeks after each toothbrushing protocol, with a 1-month washout interval. The toothbrushes used were (1) a CBT, (2) an orthodontic toothbrush (OT), and (3) an OT in combination with interproximal toothbrush (IT) (OT + IT). Total labial surfaces of the anterior teeth and stained plaque areas were measured and gingival indices (GIs) were also recorded. Repeated measures analysis of variance and Tukey's Honestly Significant Difference multiple range tests showed that the OT + IT produced a statistically significant decrease in the mean plaque percentage both for the total labial (7.2%) and interproximal (17.7%) tooth surfaces, when compared with the other toothbrushing protocols (P < 0.05). No statistically significant differences were found between the CBT and OT for the amount of bacterial plaque and GI scores (P > 0.05). Neither the CBT nor the OT alone was able to remove plaque under the archwires in poor-toothbrushing patients. Therefore, the use of ITs should be mandatory for effective plaque removal in these patients.

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.

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.