Physical properties of root cementum: Part 25. Extent of root resorption after the application of light and heavy buccopalatal jiggling forces for 12 weeks: A microcomputed tomography study.

INTRODUCTION: The aims of this study were to evaluate with microcomputed tomography the orthodontically induced inflammatory root resorption in premolars caused by buccopalatal jiggling movement with light and heavy forces and to compare it with the resorption caused by equivalent but continuous buccal forces. METHODS: The sample consisted of 60 maxillary first premolars collected from 30 patients (15 girls, 15 boys; ages, 13-18 years) who required orthodontic treatment with extractions. They were divided into 3 groups of 10 patients. Light (25 g) or heavy (225 g) buccal tipping orthodontic forces were randomly assigned on the maxillary right or left quadrant with either continuous buccal (positive controls) or buccopalatal jiggling forces for 12 weeks. At the end of the experimental period, the teeth were carefully extracted and processed for 3-dimensional imaging and volumetric evaluations of resorption craters. Data were analyzed with Wilcoxon signed rank tests. RESULTS: There was no statistically significant difference between positive control light (P = 0.0173) and heavy (P = 0.0173) continuous forces and jiggling forces for both force magnitudes. However, statistically significant differences were observed between heavy and light jiggling forces (P = 0.038), with heavy jiggling forces causing greater total root resorption than light jiggling forces. CONCLUSIONS: Light and heavy jiggling forces in the buccopalatal direction did not cause significantly different amounts of root resorption when compared with continuous forces of the same magnitude. On the other hand, light jiggling forces resulted in less root resorption than heavy jiggling forces.

Physical properties of root cementum: part 24. Root resorption of the first premolars after 4 weeks of occlusal trauma.

INTRODUCTION: In orthodontics, adding restorative materials on occlusal or lingual surfaces is a common method to create a mini-biteplane to increase patients' vertical dimension temporarily to facilitate several treatment procedures. However, this method transmits excessive occlusal forces through the periodontal ligament and causes trauma. In this prospective randomized clinical trial, we measured and compared quantitatively the volumes of root resorption after 4 weeks of occlusal trauma. METHODS: Forty-eight maxillary and mandibular first premolars of 12 patients (6 girls, 6 boys) comprised the sample for this study. One side of each patient was randomly selected as the control. On the contralateral side, a light-cured glass ionomer cement (Transbond Plus Light Cure Band Adhesive; 3M Unitek, Monrovia, Calif) was bonded onto the occlusal surface of the mandibular first premolar so that the cement was in contact with the maxillary first premolar. After 4 weeks, both first premolars were extracted. Each sample was imaged using a microcomputed tomography system (1172; SkyScan, Aartselaar, Belgium) and analyzed with specially designed software for volumetric measurements of resorption craters. Furthermore, pain was evaluated with a visual analog scale for 7 days. RESULTS: There were significant differences in the amounts of root resorption between the control and the experimentally traumatized teeth. No significant difference among the buccal, lingual, mesial, and distal surfaces was found in either jaw. Furthermore, no significant difference existed in the amount of root resorption among the cervical, middle, and apical thirds of both jaws. There was no correlation between age, sex, volume of the root resorption craters, and pain. CONCLUSIONS: Restorative buildups, used to increase the vertical dimension by 2 mm for 4 weeks, caused root resorption along the sides of the teeth during the active bite-increase period.

Advancement of the premaxilla with distraction osteogenesis.

OBJECTIVES: The aim of this study was to evaluate the effects of premaxillary advancement with distraction osteogenesis (DO) on the skeletal, dental, and soft tissues. MATERIALS AND METHODS: A total of 21 cases with Angle class I molar relationship and negative overjet or edge-to-edge incisor relationship were included. Due to patient relocation during fixed orthodontic treatment the results of 19 patients (9 females, 10 males) were reported. Their average chronological age was 16.18 ± 3.10 years. An individual tooth-borne distraction appliance was used. Skeletal, dental, and soft tissue changes were evaluated on cephalograms obtained before treatment (T1), at the end of the consolidation period (T2) and fixed orthodontic treatment (T3). Friedman and Wilcoxon tests were applied to determine the significant differences during T1-T2, T2-T3, and T1-T3 periods. RESULTS: At T2 forward movements of ANS, A, and upper incisors were significant. Significant increases of SNA, ANB, and overjet were obtained. The soft tissue points of Pn, Sn, Ss, Ls showed significant anterior movement. Arch length increase of 10.76 mm was significant. At T3 the decreases of SNA and ANB angles, and FH ┴ N-A distance were significant. Pn point showed significant anterior movement. Total treatment time showed significant anterior movement of points ANS, A, and upper incisors. Significant increase of SNA and ANB angles was noted. The soft tissue points followed the movement of the underlying hard tissue. LIMITATION: A class III control group could not be established for ethical reasons. CONCLUSIONS: The facial profile was improved and space was obtained to solve the maxillary anterior crowding with premaxillary advancement through DO.

Evaluation of Lingual Frenulum Using Geometric Morphometrics / Evaluación del Frenillo Lingual Utilizando Morfometría Geométrica

A fold of tissue, the lingual frenulum, extends onto the inferior surface of the tongue from near the base of the tongue on midline. The shape, length and alignment of lingual frenulum vary between individuals. The aim of this study is to evaluate morphology of lingual frenulum with respect to gender. Ninety seven volunteers who were students and employees of Zonguldak Karaelmas University, School of Medicine participated in the study. Two individuals with a history of hepatitis and 20 individuals with inadequate photographs were excluded from the study. Morphometric analyses were performed on the photographs of 75 volunteers (36 men, 39 women). Lingual frenulum photograph of each individual was taken using standard photographic techniques. The individual opened his/her mouth as much as possible with the tongue in contact with the interior surface of the two middle incisors. The morphology of the lingual frenulum was evaluated with linear measurements and geometric morphometrics methods. The length of lingual frenulum between the attachments of it, to the floor of the mouth and the inferior surface of the tongue were measured using Digimizer software. Four reference points determined previously were marked by tpsDig2 software on photographs. This process was repeated for each sample to create a txt file containing reference points of 75 individuals. Statistical analysis of txt files were carried out using Morpheus software. There were no statistically significant differences between the linear measurements of lingual frenulum according to gender (p>0.05). Lingual frenulum had no gender differences according to geometric morphometrics analysis as well (p>0.05). It can be suggested that lingual frenulum had similar architecture in both sexes.

Un pliegue de tejido, el frenillo lingual, se extiende sobre la superficie inferior de la lengua cerca de su base en la línea mediana. La forma, la longitud y la alineación del frenillo lingual pueden variar entre los individuos. El objetivo de este estudio fue evaluar la morfología del frenillo lingual con respecto al sexo. Participaron en el estudio 97 voluntarios, estudiantes y empleados de la Facultad de Medicina de la Universidad Zonguldak Karaelmas. Dos individuos con antecedentes de hepatitis y 20 personas con fotografías inapropiadas fueron excluidas del estudio. El análisis morfométrico se llevó a cabo en las fotografías de 75 voluntarios (36 hombres y 39 mujeres). La fotografía del frenillo lingual de cada individuo fue tomada usando las técnicas fotográficas convencionales. Cada individuo abrió su boca tanto como fue posible con la lengua en contacto con la superficie interna de los dos incisivos centrales superiores. La morfología del frenillo lingual se evaluó con métodos de medidas lineales y morfometría geométrica. La longitud del frenillo lingual entre su origen e inserción del suelo de la boca a la superficie inferior de la lengua se midieron utilizando el software Digimizer. Cuatro puntos de referencia determinados previamente fueron marcados mediante el software tpsDig2 en cada fotografía. Este proceso se repitió en cada muestra para crear un archivo txt que contuviera los puntos de referencia de 75 personas. El análisis estadístico de los archivos txt se llevó a cabo utilizando el software Morpheus. No hubo diferencias estadísticamente significativas entre las mediciones lineales de frenillo lingual, en función del sexo (p>0,05). El frenillo lingual no tuvo diferencias de sexo según el análisis de morfometría geométrica (p>0,05). Se puede sugerir que el frenillo lingual tiene una arquitectura similar en ambos sexos.

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.

Advancement of mandibular symphysis with distraction osteogenesis.

This case report demonstrates the effects of mandibular symphysis advancement with distraction osteogenesis (DO) in a 21-year-old man with a Class I molar relationship, protrusive maxillary incisors, crowding in both arches, and increased overjet and overbite. Treatment consisted of maxillary arch leveling, mandibular incisor repositioning through mandibular symphysis advancement with DO, and subsequent mandibular arch leveling. The osteotomy line, between the canine and the first premolar, was extended from the interdental area to the lower border of the mandibular symphysis bilaterally. The distraction device was cemented after mobilization of the mandibular symphysis. The screws were activated (0.8 mm per day) after a latent period of 1 week. The amount of activation per side was 6.4 mm. After an 8-week consolidation period, the distraction appliance was removed. At the end of treatment, increases of SNB angle, effective mandibular length, SN/GoGn, anterior facial height, mandibular incisor inclinations, and labiomental angle were observed. Decreases of ANB angle, overjet, and distance from the lower lip to the esthetic line were noted. Even though this patient's long-term results are not yet available, the results so far are encouraging. Mandibular symphysis advancement with DO seems to be an effective method for correcting mandibular anterior crowding and an increased overjet.

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.

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.

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.