Physical properties of root cementum: part 20. Effect of fluoride on orthodontically induced root resorption with light and heavy orthodontic forces for 4 weeks: a microcomputed tomography study.

INTRODUCTION: The major side effect of orthodontic treatment is orthodontically induced inflammatory root resorption. Fluoride was previously shown to reduce the volume of the root resorption craters in rats. However, the effect of fluoride on orthodontically induced inflammatory root resorption in humans has not yet been investigated. The aim of this study was to investigate the effect of high and low amounts of fluoride intake from birth on orthodontically induced inflammatory root resorption under light (25 g) and heavy (225 g) force applications. METHODS: Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from 2 cities in Turkey with high and low fluoride concentrations in the public water of ≥ 2 and ≤ 0.05 ppm, respectively. The patients were randomly separated into 4 groups of 12 each: group 1, high fluoride intake and heavy force; group 2, low fluoride intake and heavy force; group 3, high fluoride intake and light force; and group 4, low fluoride intake and light force. Light or heavy buccal tipping orthodontic forces were applied on the maxillary first premolars for 28 days. At day 28, the teeth were extracted, and the samples were analyzed with microcomputed tomography. RESULTS: Fluoride reduced the volume of root resorption craters in all groups; however, this effect was significantly different with high force application (P = 0.015). It was also found that light forces caused less root resorption than heavy forces. There was no statistical difference in the amount of root resorption observed on root surfaces (buccal, lingual, mesial, and distal) in all groups. However, the middle third of the roots showed the least root resorption. With high fluoride intake and heavy force application, less root resorption was found in all root surfaces and root thirds. CONCLUSIONS: Fluoride may reduce the volume of root resorption craters. This effect is significant with heavy force applications (P <0.05). The cervical and apical thirds of the root showed significantly greater root resorption after the application of buccal tipping force for 4 weeks.

Effects of fluorosis on the shear bond strength of orthodontic brackets bonded with a self-etching primer.

The aim of this study was to compare the shear bond strength (SBS) of brackets bonded to fluorosed and non-fluorosed teeth with self-etching primer (SEP) and phosphoric acid (PA). The study involved 40 mildly fluorosed [Thylstrup-Fejerskov (TFT) Index = 1-3] and 40 non-fluorosed human premolar teeth. The fluorosed and non-fluorosed teeth were randomly divided into two subgroups. In the first subgroup, 37 per cent PA was applied for 30 seconds and in the second, a SEP (Transbond Plus) was used. The brackets were bonded with light-cure adhesive paste (Transbond XT) and cured for 20 seconds. The SBSs were measured after 1000 thermocyclies. Two-way analysis of variance, Tukey's multiple comparison test, and Weibull analysis were used for the evaluation of SBS values. Bond failure locations were determined with the adhesive remnant index (ARI) and were compared with the Kruskal-Wallis and Mann-Whitney U-tests. The mean SBS was 9.01 MPa for the fluorosed teeth bonded with SEP. This value was significantly different from those of fluorosed teeth etched with PA (15.22 MPa) and non-fluorosed teeth conditioned with SEP (12.95 MPa) and PA (15.37 MPa). The ARI scores of the fluorosed teeth conditioned with SEP were significantly lower than those of non-fluorosed teeth conditioned with SEP or PA. The results of this in vitro study suggest that there are no differences in the SBS of orthodontic brackets between mildly fluorosed and non-fluorosed enamel etched with 37 per cent PA for 30 seconds. The SEP showed lower SBS values for orthodontic brackets bonded to mildly fluorosed enamel. The findings provide some evidence that routine clinical use of a SEP to bond brackets to mildly fluorosed teeth cannot be supported.

The effect of fluoride on orthodontic tooth movement in humans. A two- and three-dimensional evaluation.

AIMS: The aim of the present study was to determine whether high and low fluoride concentrations in drinking water affected the early stages of tooth movement when heavy and light orthodontic forces were applied for 4 weeks. A further aim was to compare and evaluate the resulting two-dimensional (2-D) and three-dimensional (3-D) orthodontic tooth movement. METHODS: The sample consisted of 96 maxillary upper first premolars from 48 patients who required premolar extractions as part of their orthodontic treatment. Patients were selected from two different cities in Turkey with low and high fluoride concentrations of 0.05 and 2 ppm, respectively. The patient sample was divided into four groups according to the magnitude of force applied to the first premolars and the concentration of fluoride in the public water supply; Group 1, High fluoride intake (> or = 2 ppm)-Heavy force (225 g); Group 2, Low fluoride intake (< or = 0.05 ppm)-Heavy force; Group 3, High fluoride intake-Light force (25 g); and Group 4, Low fluoride intake-Light force. A light or heavy buccal tipping orthodontic force was applied to the upper first premolars for 4 weeks. The first three palatal rugae were used for the superimposition of patient casts in a 2-D and 3-D evaluation of generated movements. RESULTS: It was found that heavy force application and fluoride intake increased the average rate of tooth movement. It was further shown that age was negatively correlated with tooth movement in the 2-D and 3-D measurements. CONCLUSIONS: The average rate of tooth movement was found to be greater in the heavy force and high fluoride intake group (Group 1HH). Age was negatively correlated with orthodontic tooth movement. Two- and three-dimensional methods were accurate for the assessment of tooth movement after four weeks of buccal tipping force application when the palatal rugae were used for superimposition.

Shear bond strength of a self-etching primer after 10,000 and 20,000 thermal cycles.

PURPOSE: To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP)after 10,000 and 20,000 thermal cycles. The tested hypothesis was that 10,000 and 20,000 thermal cycles would affect the bond strength of metal brackets bonded to enamel with the self-etching primer. MATERIALS AND METHODS: Brackets were bonded to bovine incisors with two etching protocols. In group CM (conventional method), teeth were etched with 37% phosphoric acid for 30 s. In group SEP, a self-etching primer (Transbond Plus, 3M Unitek) was applied. Brackets were bonded with light-curing adhesive (Transbond XT, 3M Unitek). The SBSs were determined after water storage at 370°C for 24 h, after 10,000 and 20,000 cycles of thermocycling. RESULTS: For both groups (CM and SEP), SBSs decreased with 10,000 and 20,000 thermal cycles. These decreased SBSs were significantly different from the values obtained with no thermocycling. Highest SBSs were observed with no thermocycling for groups CM and SEP (18.6 and 18.0 MPa, respectively). These values were not statistically different from each other. Lowest SBSs were obtained with 10,000 and 20,000 thermal cycles for group SEP (14.2 and 14.7 MPa, respectively). These values were significantly different from all other SBSs. CONCLUSION: This study indicates that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after 10,000 and 20,000 thermal cycles.

Activation-deactivation rapid palatal expansion and reverse headgear in Class III cases.

The aim of this study was to evaluate and compare the dentofacial effects of 1 week rapid palatal expansion (RPE) and activation-deactivation (A/D) RPE protocols with reverse headgear (RH). Two groups, each containing 15 subjects, were included in this study. In the RPE group (seven males and eight females, 11.94 ± 1.62 years), Hyrax screws were activated every 12 hours for 1 week. At the end of this period, RPE was stopped and the patients were instructed to wear the RH. In the A/D-RPE group (seven males and eight females, 11.34 ± 1.81 years), the screws were activated every 12 hours for 1 week. Subsequently, the screws were deactivated every 12 hours for 1 week followed by activation and deactivation for the following 2 weeks. After this protocol, the patients were instructed to use the RH. A total force of 700 g was applied to both groups for 16-18 hours/day for the first 3 months, for 12 hours/day for the second 3 months, and for 6 hours/day for the second 6 months. Lateral cephalometric films were taken before treatment (T1) and at the end of the first (T2) and second (T3) 6 months to evaluate the dentofacial changes. Intragroup differences of each landmark at T2-T1, T3-T2, and T3-T1 were analysed with a paired t-test (P < 0.016), and intergroup differences were compared with an independent t-test (P < 0.05). Anterior movement of point A (4.13 mm) for the A/D-RPE group was approximately twice of the RPE group (2.33 mm; P < 0.001). Backward movement of the mandible showed no significant difference between the groups. Anterior face height increases did not demonstrate significant differences between the groups. The pronounced anterior movement of point A demonstrates that the A/D-RPE procedure positively affects maxillary protraction.

Debonding characteristics of a polymer mesh base ceramic bracket bonded with two different conditioning methods.

The aim of this study was to compare the shear bond strength (SBS) and debonding characteristics of a polymer mesh base ceramic bracket bonded with two different surface conditioning methods. InVu Readi-Base ceramic brackets were bonded to 100 human premolars with different etching protocols. With conventional method (CM), the teeth were etched with 37 per cent phosphoric acid for 30 seconds, while Transbond Plus self-etching primer (SEP) was applied as recommended by the manufacturer. SBS testing was performed on 25 samples of each group while the remaining 25 samples of each group were subjected to plier or machine debonding after thermocycling for 1000 cycles. The adhesive remnant index (ARI) was used to determine the amount of composite resin on the enamel. Statistical analysis included Kruskal-Wallis and Mann-Whitney U-tests and Weibull analysis. No significant difference was observed between the CM (9.22 MPa) and SEP (9.04 MPa) groups (P=0.684). ARI scores of machine and plier debonding for both groups showed a significant difference (P

Thermocycling effects on shear bond strength of a self-etching primer.

OBJECTIVE: To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP) after 0, 2000, and 5000 thermal cycles. MATERIALS AND METHODS: Brackets were bonded to bovine incisors with two etching protocols. In the control group (conventional method) teeth were etched with 37% phosphoric acid. In the experimental group, an SEP (Transbond Plus) was applied as recommended by the manufacturer. Brackets were bonded with light-cure adhesive paste (Transbond XT) and light cured for 20 seconds in both groups. The SBSs were measured after water storage at 37 degrees C for 24 hours, after 2000 and 5000 cycles of thermocycling between 5 degrees C and 55 degrees C. Bond failure location was determined with the Adhesive Remnant Index (ARI). RESULTS: In the control group, SBSs did not show any significant differences among 0, 2000, and 5000 thermal cycles. However, in group SEP, SBSs decreased with 2000 and 5000 thermal cycles, and these decreases were significantly different from no thermocyling (P < .001). A significant difference was observed between ARI scores of the control group with 5000 thermal cycles and group SEP with no thermal cycles (P < .003). In addition, a significant difference was found between group SEP with no thermocycling and with 5000 thermal cycles (P < .003). CONCLUSION: The results of this study indicate that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after thermocycling.

12-month self-ligating bracket failure rate with a self-etching primer.

OBJECTIVE: To compare the clinical performance of a self-etching primer (SEP) with a conventional two-step etch and primer method (CM). MATERIALS AND METHODS: Study subjects were 39 patients with a mean age of 15 years 7 months. Six hundred and eighty-eight brackets were bonded by one operator with a split-mouth design, using Transbond Plus Self-Etching Primer or a conventional two-step etch and primer (Transbond XT). The survival rate of the brackets was estimated by the Kaplan-Meier analysis. Bracket survival distributions with respect to bonding procedure, dental arch, type of tooth (incisor, canine, and premolar) and patients' gender were compared using the log-rank test. Bond failure interface was determined using the Adhesive Remnant Index (ARI). RESULTS: The bond failure rates of SEP and CM were 4.7% and 1.7%, respectively. A significant difference was found between the bonding procedures using the log-rank test (P < .05). Furthermore, canine and premolar teeth displayed a lower survival rate than incisor teeth (P < .05). Survival rates did not show significant differences between the upper and lower dental arches and patients' gender (P > .05). No significant difference was observed for ARI scores (P > .05). CONCLUSION: These findings indicate that the SEP (Transbond Plus) can be effectively used to bond orthodontic brackets.

Effects of self-etching primer on shear bond strength of orthodontic brackets at different debond times.

OBJECTIVE: To evaluate the effect of a self-etching primer on shear bond strengths (SBS) at the different debond times of 5, 15, 30, and 60 minutes and 24 hours. MATERIALS AND METHODS: Brackets were bonded to human premolars with different etching protocols. In the control group (conventional method [CM]) teeth were etched with 37% phosphoric acid. In the study group, a self-etching primer (SEP; Transbond Plus Self Etching Primer; 3M Unitek, Monrovia, Calif) was applied as recommended by the manufacturer. Brackets were bonded with light-cure adhesive paste (Transbond XT; 3M Unitek) and light-cured for 20 seconds in both groups. The shear bond test was performed at the different debond times of 5, 15, 30 and 60 minutes and 24 hours. RESULTS: Lowest SBS was attained with a debond time of 5 minutes for the CM group (9.51 MPa) and the SEP group (8.97 MPa). Highest SBS was obtained with a debond time of 24 hours for the CM group (16.82 MPa) and the SEP group (19.11 MPa). Statistically significant differences between the two groups were not observed for debond times of 5, 15, 30, or 60 minutes. However, the SBS values obtained at 24 hours were significantly different (P < .001). CONCLUSIONS: Adequate SBS was obtained with self-etching primer during the first 60 minutes (5, 15, 30 and 60 minutes) when compared with the conventional method. It is reliable to load the bracket 5 minutes after bonding using self-etching primer (Transbond Plus) with the light-cure adhesive (Transbond XT).

Saliva contamination effect on shear bond strength of self-etching primer with different debond times.

OBJECTIVE: To evaluate shear bond strengths (SBSs) of a self-etching primer (SEP) following saliva contamination at different stages of bonding at debond times of 5, 15, and 30 minutes and 24 hours. MATERIALS AND METHODS: Two-hundred forty human premolars were divided into four groups: group 1, uncontaminated; group 2, saliva contamination after priming; group 3, saliva contamination before priming; and group 4, saliva contamination before and after priming. Four subgroups according to debond times of 5, 15, 30 minutes and 24 hours were composed. Metal brackets were bonded with an SEP (Transbond Plus) and light-cure adhesives paste (Transbond XT). SBS values and the adhesive remnants were determined. RESULTS: The highest SBS was obtained at a debond time of 24 hours for the control group. This was significantly different from the other groups. SBSs at 5, 15, and 30 minutes showed no significant difference from each other in the control group (P>.05). Lowest SBSs were obtained at a debond time of 5 minutes for groups 1, 2, 3, and 4 (8.38, 7.10, 7.06, and 6.26 MPa, respectively) and were not significantly different from each other (P>.05). SBSs at 24 hours were not significantly different from each other for groups 2, 3, and 4 (P>.05). Significant differences were found in the adhesive remnant (P<.001). CONCLUSIONS: SEP (Transbond Plus) may produce clinically acceptable bracket bonding after 5, 15, and 30 minutes from time of placement on the teeth, even with light and heavy saliva contamination.

Effect of fluoride on root resorption following heavy and light orthodontic force application for 4 weeks and 12 weeks of retention.

OBJECTIVE: To evaluate the null hypothesis that fluoride intake via drinking water has no effect on orthodontic root resorption in humans after orthodontic force application for 4 weeks and 12 weeks of retention. MATERIALS AND METHODS: Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from two cities in Turkey. These cities had a high and low fluoride concentration in public water of ≥2 pm and ≤0.05 pm, respectively. The patients were randomly separated into four groups of 12 each: group 1HH, high fluoride (≥2 ppm) and heavy force (225 g); group 2LH, low fluoride (≤0.05 ppm) and heavy force; group 3HL, high fluoride and light force (25 g); and group 4LL, low fluoride and light force. Light or heavy buccal tipping force was applied on the upper first premolars for 28 days. At day 28, the left premolars were extracted (positive control side); the right premolars (experimental side) were extracted after 12 weeks of retention. The samples were analyzed with microcomputed tomography. RESULTS: On the positive control side, under heavy force application, the high fluoride groups exhibited less root resorption (P  =  .015). On the experimental side, it was found that fluoride reduced the total volume of root resorption craters; however, this effect was not statistically significant (P  =  .237). Moreover, the results revealed that under heavy force application experimental teeth exhibited more root resorption than positive control groups. CONCLUSION: The null hypothesis could not be rejected. High fluoride intake from public water did not have a beneficial effect on the severity of root resorption after a 4-week orthodontic force application and 12 weeks of passive retention.

Evaluation of survival of 3 different fixed space maintainers.

PURPOSE: The purpose of this study was to provide a comparative evaluation of the survival times and failure rates of different types of fixed space maintainers (SMs). METHODS: A total of 30 4- to 10-year-olds were selected for the study. Children were divided into 3 groups, according to type of SM, namely: band and loop (B&L), direct bonded (DB), and fiber-reinforced composite (FRC). Patients were recalled once every 3 months for clinical evaluation for 1 year or until failure. The survival times of SMs were estimated by means of the Kaplan-Meier method, and confounding factors were investigated using Cox regression analysis. RESULTS: Mean survival time was highest for B&L SMs (11.20 months), followed by DB SMs (9.20 months) and FRC SMs (6.70 months). There were statistically significant differences noted between types of SMs (log rank=11.99; P=.002). The Cox proportional hazards model revealed that age, sex, dental arch, and side of the jaw were not significantly correlated with "success of SMs" (P>.05). CONCLUSIONS: Band and loop fixed space maintainers showed superior performance in terms of both survival time and success rates versus direct bonded and fiber-reinforced composite space maintainers.

Multidisciplinary treatment of a subgingivally fractured tooth with indirect composite restoration: a case report.

In pediatric patients, anterior teeth with fractures that extend subgingivally require a complex treatment plan that addresses biologic, esthetic, and functional factors, such as mastication and speech. The purpose of this clinical report was to describe a technique using indirect composite restoration to restore a subgingivally fractured permanent maxillary right central incisor in a 10-year-old boy. Due to the complex nature of the treatment, a multidisciplinary approach was used to restore the tooth. The crown fragment was removed, and endodontic treatment was performed. The tooth was then extruded orthodontically. A glass fiber post was placed to improve retention, and an indirect composite restoration was placed. A clinical and radiographic evaluation at a follow-up appointment 1 year later confirmed that the technique used in this case can be a good option for restoring anterior teeth with subgingival fractures.

Color preferences of patients receiving elastic ligatures.

OBJECTIVES: To determine the color preferences for elastic ligatures among patients receiving fixed-appliance orthodontic therapy. METHODS: Five hundred patients with metal brackets (336 female patients and 164 male patients) were included, and their color preferences for elastic ligatures were recorded using a color scale. Chi-square analysis was performed to evaluate the color preferences and to determine the influence of age and gender on color preferences (P<.05). RESULTS: Two hundred and seventy-six patients (55.2%) preferred strikingly colorful elastic ligatures, while 224 patients (44.8%) preferred less noticeable elastic ligatures. No significant difference was observed between the color preferences of female and male patients (P>.05). However, significant differences were observed between the color preferences of adolescents and older patients (P<.001). CONCLUSIONS: Female patients preferred red-purple-colored tones, while male patients preferred blue-black-colored tones. Adolescents preferred colorful elastic ligatures, while older patients preferred ligatures with less-noticeable colors. A stock of 10-12 colorful and less-noticeable elastic ligatures seems to be adequate to ensure patient satisfaction.

Six-month bracket failure rate evaluation of a self-etching primer.

The aim of this study was to compare the clinical performance of a self-etching primer (SEP) with a conventional two-step etch and primer [conventional method (CM)]. The chair time required for bonding was also evaluated. Thirty-seven patients (14 males and 23 females) with a mean age of 16 years 5 months were included in the study. Six hundred and seventy-two brackets were bonded by one operator using a split-mouth design, with either SEP (Transbond Plus) or CM (Transbond XT). Bracket failure rates were estimated with respect to bonding procedure, dental arch, type of tooth (incisor, canine, and premolar), and gender. The results were evaluated using the chi-square test. The survival rate of the brackets was estimated with Kaplan-Meier analysis. Bracket survival distributions with respect to bonding procedure, dental arch, type of tooth, and patient gender were compared with a log-rank test. Bond failure interface was determined with the adhesive remnant index (ARI). The failure rates were 0.6 per cent for both bonding procedures. The failure and survival rates did not show significant differences between the bonding procedures, upper and lower dental arches, or gender. However, premolar brackets displayed a higher bond failure rate and a lower survival rate than incisor and canine brackets (P < 0.05). The mean bracket bonding time per tooth with SEP was significantly shorter than with CM (P < 0.001). No significant difference was observed for the ARI scores (P > 0.05). The results of this in vivo, randomized, cross-mouth clinical trial demonstrated a high survival rate with Transbond Plus. This finding indicates that SEP can be effectively used for bonding of orthodontic brackets.