Accuracy of 3 Soft Tissue Prediction Methods After Double-Jaw Orthognathic Surgery in Class III Patients.

PURPOSE: We aimed to evaluate the accuracy and validity of conventional manual prediction method (CM) and 2-dimensional and 3-dimensional (3D) soft tissue prediction methods for Class III bimaxillary orthognathic surgery patients. METHODS: Twenty skeletal Class III patients were included in this study. Soft tissue prediction was achieved with a traditional manual technique, 2-dimensional software (Dolphin Imaging, version 11.5), and 3-dimensional software (SimPlant Master, version 16.0) on preoperative lateral cephalometric radiographs and cone beam computurized tomography (CBCT) images and then compared with postoperative lateral cephalometric radiographs obtained at least 6 months after surgery (mean, 11.5 ± 6.77 months). Forty-eight measurements were done to determine the reliability of the methods. RESULTS: All prediction methods have limited postsurgery prediction accuracy for the subnasal upper lip area. Most of the differences were not more than 3 mm for all study groups, except the 3D software, which predicted the upper lip area to be, on average, 3.08 ± 1.38 mm further back (P < 0.001). Although the conventional method predicted 20 of 48 measurements similar to the final results, the poorest predictions were found at the nasal and labiomental areas (P < 0.001). Two-dimensional software predicted 23 of 48 measurements very close to the final results but made significantly different predictions for the nasolabial and labiomental angles, labrale superius point, and the chin area. CONCLUSIONS: The 3D method predicted, especially the upper lip area, to be significantly and clinically incorrect, and its soft tissue prediction was insufficient compared with the other 2 methods. The 3D software needs to be updated, especially in evaluating soft tissue A point and upper lip changes after surgery.

Effects of mesenchymal stem cell transfer on orthodontically induced root resorption and orthodontic tooth movement during orthodontic arch expansion protocols: an experimental study in rats.

OBJECTIVES: The aim was to evaluate the effects of mesenchymal stem cell (MSC) transfer to periodontal ligament (PDL) on the inhibition and/or repair of orthodontically induced root resorption (OIRR) during and after arch expansion and on the orthodontic tooth movement (OTM) rate of the maxillary first molar teeth of rats. MATERIAL AND METHODS: Sixty Wistar rats were divided into three groups as the untreated group, MSC and control injections during the expansion period group (EMSC-EC), and MSC and control injections at the retention period group (RMSC-RC). Fifty grams of orthodontic force was applied to the maxillary first molar teeth of the rats for 14 days in the vestibular direction, and then, 20 days of retention was carried out. MSCs and control injections were performed every 3 days in the EC, RC, EMSC, and RMSC groups. At the end of the experiment, samples were prepared for OTM evaluation, mRNA expression analysis, micro-computed tomography measurements, cementum thickness calculations, and structural examinations. RESULTS: The amount of OTM in EMSC group was significantly higher than in EC group (P < 0.001). MSC transfer during the expansion and retention periods reduced the number of resorption lacunae, volumetric and linear resorptive measurements, and cyclooxygenase-2 and receptor activator of nuclear factor kappa B ligand (RANKL) mRNA expression levels, and increased the osteoprotegerin (OPG) expression levels, OPG/RANKL ratio, and cementum thickness in the EMSC and RMSC groups. CONCLUSIONS: MSC transfer to PDL during expansion increased the amount of OTM. Injection of MSC during the retention period was found to be slightly more effective in prevention and/or repair of OIRR than MSC transfer during the expansion period.

Effectiveness of incremental vs maximum bite advancement during Herbst appliance therapy in late adolescent and young adult patients.

INTRODUCTION: The purpose of this research was to compare the effects of Herbst appliance therapy using incremental vs maximum advancement in late adolescent and young adult patients with Class II skeletal malocclusion. METHODS: Forty-two patients with skeletal Class II malocclusion were treated with cast-splint Herbst appliances. The subjects were randomly allocated into 2 groups according to activation type: incremental advancement (IA) and maximum advancement (MA). Initial forward movement in the IA group was 4 to 5 mm and was followed by subsequent bimonthly advancements of 2 mm. Single-step advancement was achieved in the MA group until an edge-to-edge incisor relationship or an overcorrected Class I molar relationship was obtained. Total treatment times were 9.7 ± 1.1 months for the IA group and 9.5 ± 1.1 months for the MA group. Dental, skeletal, and soft tissue measurements were performed on lateral cephalograms taken just before and at the end of the Herbst appliance therapy. Statistical significance was set at P ≤ 0.05. RESULTS: All mandibular skeletal dimensions increased, and improvements of the sagittal maxillomandibular parameters were found in both groups. Protrusion and proclination of the mandibular incisors were greater in the IA group (95.90° ± 5.34°) compared with the MA group (92.04° ± 7.92°). Other dentoalveolar changes in both groups were intrusion of the maxillary first molars, and extrusion of the mandibular first molars and maxillary incisors. The mentolabial sulcus was flattened, soft tissue convexity was reduced, and forward movement of mandibular soft tissues was seen after Herbst therapy. CONCLUSIONS: Similar skeletal, dental, and soft tissue changes were obtained in both groups after Herbst therapy. Greater proclination and more protrusion of the mandibular incisors were found in the IA group.

Changes in pharyngeal airway dimensions following incremental and maximum bite advancement during Herbst-rapid palatal expander appliance therapy in late adolescent and young adult patients: a randomized non-controlled prospective clinical study.

OBJECTIVES: This was a parallel, assessor-blinded, randomized, non-controlled prospective trial with the objective to evaluate and compare the effects of maximum advancement (MA) and incremental advancement (IA) of mandible with cast-splint-type Herbst-rapid palatal expander (RPE) appliance on pharyngeal airway dimensions and hyoid bone position in skeletal Class II late adolescents and young adults. MATERIALS AND METHODS: A total of 48 patients (19 male and 29 female, mean age: 15.45 ± 1.42 years) with skeletal Class II malocclusion were treated with cast-splint Herbst-RPE appliance. Inclusion criteria were skeletal Class II malocclusion, mandibular retrognathia, bilateral Class II molar and canine relationship, increased overjet, normal or decreased vertical dimensions, minimal crowding, and no missing teeth. Enrolled subjects were randomly allocated into two groups according to mandibular advancement type: IA and MA Herbst-RPE therapy. The outcome assessor was blinded. Advancement in MA group was adjusted until tête-à-tête incisor relationship or super Class I molar relationship was obtained. Initial forward movement in IA group was 4-5 mm and followed by bimonthly 2 mm of subsequent advancements. Skeletal, pharyngeal airway, and hyoid measurements were performed using lateral cephalometric films. Statistical significance was set at P value of less than 0.05. RESULTS: Hypopharyngeal airway dimensions (P < 0.000), oropharyngeal airway dimensions (P < 0.001, P < 0.007), and PASmin values (P < 0.010, P < 0.009) were increased and soft palate angle (P < 0.018, P < 0.007) was decreased in MA and IA groups significantly. Hyoid bone measurements revealed a significant difference in H-Cv2 distance (MA: P < 0.002-P < 0.002; IA: P < 0.001-P < 0.043) and H-Cv3 distance (P < 0.005, P < 0.001) for both groups. However, all these changes did not differ among the MA and IA activation groups. ANB°, Wits, overjet, and overbite measurements decreased and SNB°, Co-Gn, Na-Me, ANS-Me, and S-Go increased with the treatment significantly in both mandibular advancement groups (P < 0.000-P < 0.040). CONCLUSIONS: Herbst-RPE appliance provided a similar improvement in the oropharyngeal and hypopharyngeal airway dimensions and similar changes in sagittal and vertical hyoid position for both maximum and IA protocols in patients with skeletal Class II malocclusion. TRIAL REGISTRATION: ISRCTN69743543.

Effects of Surgical and Nonsurgical Rapid Maxillary Expansion on Palatal Structures.

AIM: The aim of the present study was to compare the effects of surgical and nonsurgical rapid maxillary expansion (RME) in skeletally mature patients. MATERIALS AND METHODS: Surgically assisted rapid maxillary expansion (SARME) was used in 18 patients (2 males, 16 females) with a mean age of 19.90 years. Two nonsurgical RME groups were constructed to compare the expansion changes of SARME. Eighteen patients in maximum pubertal peak (12 males, 6 females) with a mean age of 13.04 years comprised the growing RME group, while the nongrowing RME (NG-RME) group consisted of 18 skeletally mature patients (1 male, 17 females) with a mean age of 16.41 years. Thirteen linear and 2 angular measurements were made on the study models taken before expansion (T0) and after 3 months of retention period (T1). Intragroup differences were evaluated with paired t test and the intergroup differences were analyzed with 1-way analysis of variance. RESULTS: All groups showed significant transversal skeletal and dental expansion. The palatal width changes at gingival and midpalate levels were the highest in the NG-RME group (6.85 and 5.84 mm, respectively). The most molar tipping was in the NG-RME group (15.00°) and the palatal vault angle showed the most increase in the SARME group (9.77°). The greatest expansion at the base of palatal vault was in the SARME group (4.42 mm). CONCLUSIONS: The pattern of expansion was rotation of the maxillary halves for SARME and lateral displacement of the dentoalveolar structures for NG-RME. Patients with severe skeletal discrepancy or increased age are good candidates for SARME.

Rate of tooth movement and dentoskeletal effects of rapid canine retraction by dentoalveolar distraction osteogenesis: A prospective study.

INTRODUCTION: The purpose of this study was to test the null hypothesis that duration of orthodontic treatment can be significantly reduced by accelerating canine retraction using dentoalveolar distraction (DAD). METHODS: Thirty-six maxillary canines of 19 patients comprised the DAD group, and 28 canines of 14 patients were included in the distalization group (DG). The initial mean ages were 15.8 ± 1.96 years for the DAD group and 16.02 ± 2.8 years for the DG. A custom-made, rigid, tooth-borne intraoral distraction device was used for the DAD group, and intraoral elastics were applied for canine distalization in the DG. Six skeletal and 11 dental variables were measured for the cephalometric evaluation. RESULTS: Canine retraction was 7.9 ± 1.49 mm in 11.8 ± 1.3 days and canine distal tipping was 11.48° ± 4.37° after DAD; the canines were distalized 5.29 ± 2.01 mm and tipped 13.64° ± 9.54° in 200 ± 57 days in the DG. The rates of posterior canine movement were 0.67 ± 0.14 mm per day after DAD and 0.03 ± 0.01 mm per day in the DG. No significant first molar anchorage loss was observed after DAD, although the DG showed some vertical and sagittal first molar movement. CONCLUSIONS: We failed to reject the null hypothesis. DAD can reduce the duration of orthodontic treatment time by accelerating canine retraction in extraction patients without undesirable side effects.

Effects of cell-mediated osteoprotegerin gene transfer and mesenchymal stem cell applications on orthodontically induced root resorption of rat teeth.

Aim: The aim of this study is to evaluate and compare therapeutic effects of mesenchymal stem cell (MSCs) and osteoprotegerin (OPG) gene transfer applications on inhibition and/or repair of orthodontically induced inflammatory root resorption (OIIRR). Materials and methods: Thirty Wistar rats were divided into four groups as untreated group (negative control), treated with orthodontic appliance group (positive control), MSCs injection group, and OPG transfected MSCs [gene therapy (GT) group]. About 100g of orthodontic force was applied to upper first molar teeth of rats for 14 days. MSCs and transfected MSC injections were performed at 1st, 6th, and 11th days to the MSC and GT group rats. At the end of experiment, upper first molar teeth were prepared for genetical, scanning electron microscopy (SEM), fluorescent microscopy, and haematoxylin eosin-tartrate resistant acid phosphatase staining histological analyses. Number of total cells, number of osteoclastic cells, number of resorption lacunae, resorption area ratio, SEM resorption ratio, OPG, RANKL, Cox-2 gene expression levels at the periodontal ligament (PDL) were calculated. Paired t-test, Kruskal-Wallis, and chi-square tests were performed. Results: Transferred MSCs showed marked fluorescence in PDL. The results revealed that number of osteoclastic cells, resorption lacunae, resorption area ratio, RANKL, and Cox-2 were reduced after single MSC injections significantly (P < 0.05). GT group showed the lowest number of osteoclastic cells (P < 0.01), number of resorption lacunae, resorption area ratio, and highest OPG expression (P < 0.001). Conclusions: Taken together all these results, MSCs and GT showed marked inhibition and/or repair effects on OIIRR during orthodontic treatment on rats.

Effect of Delayed Bonding and Antioxidant Application on the Bond Strength to Enamel after Internal Bleaching.

PURPOSE: This study evaluated the effect of delayed bonding and antioxidant application (AA, 10% sodium ascorbate) after internal bleaching (35% carbamide peroxide) on the shear bond strength of an adhesive cement to enamel. MATERIALS AND METHODS: Eighty-four human maxillary central incisors were endodontically treated. The control group remained unbleached with no AA. Experimental groups were all internally bleached. The buccal enamel was finished and polished with metallographic paper to a refinement of #600, in order to obtain a 5-mm(2) flat bonding area. An adhesive cement (Clearfil Esthetic) was placed into a plastic tube with internal diameter of 3 mm and a 3-mm height and cured on the enamel. Bonding occurred either immediately after bleaching (group Im), a 7-day delay (group 7), or a 14-day delay (group 14), and half the specimens were treated with antioxidant application (groups Im-AA, 7-AA, and 14-AA). Shear bond strength testing was performed on a universal testing machine, and data were analyzed with ANOVA and Fisher test (5%). RESULTS: Delaying of bonding is a useful factor for enhancing shear bond strength (p < 0.05), whereas AA only enhanced shear bond strength after 7 days delayed bleaching (p < 0.05). The highest bond strength was noted in groups 7-AA (20.51 ± 4.5 MPa), 14 (19.82 ± 4.6), 14-AA (20.27 ± 4.4), and control (20.51 ± 5.1), which were not significantly different from each other. CONCLUSIONS: After internal bleaching, adhesive cementation to enamel is recommended only when delayed 14 days, or delayed 7 days with sodium ascorbate application.

Differences in third molar development and angulation in class II subdivision malocclusions.

PURPOSE: To assess and compare the developmental stages and angulations of third molars between the class II and class I sides in class II subdivision malocclusions. METHODS: This retrospective study was performed using panoramic x­rays of 38 individuals (mean age: 15.5 years; 24 females, 14 males) with class II subdivision malocclusions, which were further divided into type 1 and 2 subgroups according to midline deviation, and a control group of 42 individuals (mean age: 17.0 years; 30 females, 12 males) with normal occlusion. Third molars were categorized using the developmental stages defined by the Demirjian method. Angles between the third molars and horizontal reference lines and also to the second molars were measured. RESULTS: No difference was found in developmental stages or angulations between the left and right third molars in the control group. In the class II subdivision malocclusion cases, no difference in third molar developmental stages was observed, but the angle between the long axes of the mandibular third and second molars was significantly greater on the class II side. In the type 2 subgroup, developmental stage of the maxillary third molar was more advanced on the class II side. In both subgroups, the angles of the maxillary third molars' long axis to the interorbital plane differed significantly between the two sides. CONCLUSION: Class II subdivision malocclusion may cause differences in third molar development and angulations between the two sides. Orthodontic treatment should be planned considering the third molars in this malocclusion.

How much should incisors be decompensated? periodontal bone defects during presurgical orthodontic treatment in class III double-jaw orthognathic surgery patients.

INTRODUCTION: The aims of this study were to evaluate periodontal bone defects around the lower and upper incisors and to identify changes in the buccolingual inclination of the incisors during orthodontic decompensation in skeletal Class III orthognathic surgery patients. MATERIALS AND METHODS: The sample consisted of 26 adults with skeletal Class III deformity who had undergone presurgical orthodontic treatment and orthognathic surgery. Lateral cephalograms obtained before orthodontic treatment and before surgery were used to determine the inclination and position changes of the incisors. Cephalometric measurements were taken using Dolphin Imaging 11.95. Three-dimensional images were generated from cone-beam computed tomography (CBCT) scans prior to surgery and used to detect periodontal bone defects, including fenestration (F) and dehiscence (D). RESULTS: Intraclass correlation coefficients (ICC) were determined and the measurements showed high reproducibility. The cephalometric data showed normal distribution and there were no differences between genders in terms of cephalometric changes, dehiscence, fenestration, or coexistent (D-F/DF) formation. The patients presented maxillary incisor retroclination and mandibular incisor proclination, which was consistent with the tooth decompensation. CBCT assessment was performed for a total of 208 teeth; while 81 upper and 94 lower incisors had D-F/DF formation, 23 upper and 10 lower incisors were healthy. Statistically significant correlations were not found between the inclination degree of the incisors and D-F/DF formation. CONCLUSIONS: Decompensation of incisors during presurgical orthodontic treatment increases the risk of periodontal defects. There is no linear relationship between the increase in the inclination degrees of incisors and D-F/DF formation.

Three-dimensional palatal morphology and upper arch changes following nonsurgical and surgical maxillary expansion in adults.

OBJECTIVE: The objective of this study was to evaluate the effects of nonsurgical rapid maxillary expansion (RME) and surgically assisted RME (SARME) on palatal morphology and upper arch dimensions using three-dimensional (3D) models in skeletally mature patients. STUDY DESIGN: Thirty-eight skeletally mature patients with a maxillary transverse deficiency were divided into RME and SARME groups. Nineteen patients in the RME group (mean age, 19.16 ± 2.25 years) were treated using a full-coverage bonded acrylic splint expander; 19 patients in the SARME group (mean age, 20.38 ± 3.36) were treated using the banded palatal expansion appliance with hyrax screws. The 3D models were obtained before and after expansion. The maxillary dental arch widths, maxillary first molar angulation, palatal area, and palatal volume were calculated on the 3D models. RESULTS: All variables showed statistically significant changes after the retention period (P < .001). The maxillary arch width between first premolars (P < .05), the palatal area (P < .01), and the palatal volume (P < .05) significantly increased in the SARME group compared to the RME group. The maxillary first molar tipping in the RME group was significantly higher than that in the SARME group (P < .01). CONCLUSIONS: Although SARME has more positive effects in skeletally mature patients, nonsurgical RME can be considered as an alternative by evaluating surgical risks, periodontal status, and the need for skeletal expansion.

Evaluating the changes in nasal airway volume and nasal airflow after surgically assisted rapid maxillary expansion.

OBJECTIVE: This study aims to compare the changes in the nasal airway volume and nasal airflow using acoustic rhinometry (AR), rhinomanometry (RMN), and dental volumetric tomography (DVT) after surgically assisted rapid maxillary expansion (SARME). STUDY DESIGN: Our study consists of 13 adults, 3 male and 10 female patients, aged between 15 and 26, with completed skeletal development. In our study, DVT imaging was obtained twice, preoperation and 3 months after expansion. AR and RMN measurements were recorded, and Visual Analog Score (VAS) and Nasal Obstruction Symptom Evaluation (NOSE) Scale surveys were scored at preoperation and 3 months after expansion. Nasopharyngeal-oropharyngeal airway volume and areas were calculated using the Romexis 3.8.3.R (Planmeca, Helsinki, Finland) and Nemotec V2019 (Madrid, Spain) software programs. IBM SPSS Statistics 22 (SPSS IBM, Armonk, New York) was used for statistical analysis. RESULTS: Comparing the preoperation and postexpansion measurements by both software programs revealed a statistically significant increase in the nasopharyngeal airway volume. No statistically significant change was observed in the oropharyngeal airway volume. Furthermore, we found a statistically significant increase in VAS but a significant decrease in NOSE. CONCLUSION: According to our findings, nasal airway volume increased after SARME, and although there was no significant change in nasal resistance, patients' quality of life increased significantly.

Late growth period orthopedic therapy versus bimaxillary surgery for correction of skeletal class III.

OBJECTIVE: To compare the effects of late orthopedic therapy with orthognathic surgery in skeletal class III cases. MATERIALS AND METHODS: The subjects of the study were divided into 2 groups. Group 1 comprised 15 patients (8 females and 7 males) with a mean age of 14 years 6 months (range, 12 y 10 mo to 15 y 6 mo) and treated with maxillary expansion and a modified maxillary protraction appliance (MMPA). Group 2 comprised 11 patients (6 females and 5 males) treated with bimaxillary surgery (BMS) with a mean age of 23 years (range, 18 y 2 mo to 28 y 4 mo). Lateral cephalometric films were taken before (T1) and after orthopedic therapy (T2) in the MMPA group and before surgery (T1) and after fixed orthodontic therapy (T2) in the BMS group. Study groups were compared by analysis of variance and Tukey tests at the beginning and at the end of the treatment. RESULTS: Maxillary forward displacement (P < 0.01) and the increase in ANS-Me distance (P < 0.05) were higher in the BMS group than in the MMPA group. The mandible exhibited significant posterior rotation in MMPA group (P < 0.01). Mandibular effective length decreased in the BMS group and increased in the MMPA group. Soft tissue profile (G-Sn-Pg) improved in both groups (P < 0.05) and labiomental angle reduced in the BMS group, whereas an increase was observed in the MMPA group. CONCLUSIONS: Orthognatic surgery can be more effective in patients with increased mandibular length, more anteriorly positioned mandibles, and increased vertical dimensions.

Changes in nasopharyngeal airway following orthopedic and surgically assisted rapid maxillary expansion.

INTRODUCTION: The aim of this study was to compare changes in soft-palate morphology and nasopharyngeal relations after orthopedic rapid maxillary expansion (RME) and surgically assisted RME (SARME). METHODS: A group of 10 patients received RME, a second group of 10 patients received SARME, and a third group of 10 patients served as an untreated control group. Lateral and posteroanterior cephalograms were obtained for each individual at preexpansion/precontrol and postexpansion/postcontrol. In addition to descriptive parameters, the angulation, length, and thickness of the soft palate and superior and inferior pharyngeal spaces and the ratios of the length of the soft palate to the length of the superior and inferior pharyngeal spaces were evaluated. Paired t-tests were performed to analyze changes within groups, and analysis of variance and Duncan tests were used to compare changes among groups. RESULTS: No statistically significant differences were found in changes in measurements related to soft-palate morphology or nasopharyngeal dimensions among the SARME, RME, and control groups; however, increases in soft-palate angulation and superior and inferior pharyngeal spaces after expansion/control were greater in the SARME group than in other groups. CONCLUSIONS: No statistically significant differences were found between changes in the nasopharyngeal airway after RME and SARME.

Rapid tooth movement and orthodontic treatment using dentoalveolar distraction (DAD). Long-term (5 years) follow-up of a Class II case.

The purpose of this report is to describe the dentoalveolar distraction (DAD) technique and to present its effects on the surrounding structures by presenting a Class II case. A 15-year-old skeletal and dental Class II female patient with an overjet of 9 mm was treated by DAD osteogenesis. A custom-made, rigid, tooth-borne intraoral distraction device was used for rapid canine retraction. Osteotomies surrounding the canines were made to achieve rapid movement of the canines within the dentoalveolar segment, in compliance with distraction osteogenesis principles. The amount of canine retraction was 7.5 mm in 12 days at a rate of 0.625 mm per day, with no posterior anchorage loss. The canine teeth showed 1.6 mm extrusion and 11 degrees inclination change (distal tipping) during the same period. Orthodontic treatment continued for 6 months with no clinical and radiographic evidence of complications such as root fracture, root resorption, ankylosis, and soft tissue dehiscence. The DAD technique is an innovative method, because it reduces overall orthodontic treatment time by about 50%, with no unfavorable effects on periodontal tissues and surrounding structures and with no need to use any intraoral or extraoral anchorage appliances.

Mandibular asymmetry in cleft lip and palate patients.

The aims of this study were to evaluate condylar, ramal, and condylar plus ramal mandibular vertical asymmetry in a group of cleft lip and palate (CLP) patients and compared with subjects with a 'normal' occlusion. Mandibular asymmetry index (condylar, ramal, and condylar plus ramal) and gonial angle measurements were examined on panoramic radiographs. The study groups comprised 20 unilateral cleft lip and palate (UCLP) patients (10 males and 10 females; mean age 13.03 +/- 3.33 years), 20 bilateral cleft lip and palate (BCLP) patients (10 males and 10 females; mean age 13.73 +/- 3.53 years), and a control group of 20 subjects (9 males and 11 females; mean age 14.35 +/- 2.46 years) with a normal occlusion. Kruskal-Wallis one-way analysis of variance was used to determine statistically significant differences between the groups for condylar, ramal, and condylar plus ramal asymmetry index measurements at the 95 per cent confidence interval. None of the investigated groups showed statistically significant gender differences for posterior vertical height measurements (P > 0.05). Asymmetry indices were similar, with no statistically significant differences found in any of the groups. However, gonial angle showed statistically significant differences (P < 0.05) in the UCLP group and condylar height (CH) in the BCLP patients (P < 0.001). Except for CH measurement in the BCLP group, CLP patients have symmetrical mandibles when compared with a normal occlusion sample.

Evaluation of shear bond strength of metallic and ceramic brackets bonded to enamel prepared with self-etching primer.

The aim of this in vitro study was to evaluate the shear bond strength (SBS) of different metallic and ceramic bracket bonding combinations using self-etching primers (SEPs). Eighty freshly extracted human premolar teeth were randomly divided into four equal groups for bonding with ceramic or metallic brackets as follows: group 1, metallic brackets bonded with conventional acid etching; group 2, metallic brackets bonded with Transbond Plus Self-Etching primer (TPSEP); group 3, ceramic brackets bonded as per group 1; group 4, ceramic brackets bonded as per group 2. The SBS of these brackets was measured and recorded in megapascals (MPa). The adhesive remnant index (ARI) scores were determined after bracket failure. Data were analyzed with the analysis of variance, Tukey, and chi-square tests. The bond strength of group 3 (mean: 36.7 +/- 11.8 MPa) was significantly higher than group 4 (mean: 26.6 +/- 8.9 MPa; P < 0.05), group 1 (mean: 25.5 +/- 5.1 MPa; P < 0.01), and group 2 (mean: 22.9 +/- 7.3 MPa; P < 0.001). No significant differences in debond locations were found among the groups (P > 0.05). Compared with conventional acid etching, SEPs significantly decreased the SBS of ceramic orthodontic brackets.

Comparisons of the effects of systemic administration of L-thyroxine and doxycycline on orthodontically induced root resorption in rats.

The aim of this study was to histologically evaluate and compare the effects of the systemic administration of L-thyroxine (TX) and doxycycline (DX) on orthodontically induced root resorption, Twenty-eight male 50- to 60-day-old Wistar rats were used. Seven rats served as the baseline control. Seven animals received TX (20 µg/kg bodyweight/day) and seven DX (1.2 mg/kg bodyweight/day), by means of a mini-osmotic pump implanted subcutaneously. Seven rats were separated as a sham, in order to evaluate the pure effect of the surgical procedure on the animals' health. Tooth movement (TM) was achieved with a continuous force of 50 g by placing Elgiloy coil springs between the right maxillary first molar and incisors for 14 days. The animals were sacrificed and specimens containing the appliance and maxillary tooth-bearing segments were processed for light microscopy. The surface area of root resorption lacunae was measured histomorphometrically using digital photomicrographs. To evaluate the resorptive changes on the molar root surface of each group, scanning electron microscopy (SEM) examinations were also carried out. Statistical evaluation of root resorption percentages was performed using Kruskal-Wallis analysis of variance test. Multiple comparisons were determined by the Student-Newman-Keuls method. The level of significance was set at P < 0.05. Histomorphometric analysis of root resorption, expressed as a percentage, showed that the average relative root resorption affecting the maxillary molars on the TM side was 0.32 ± 0.25 in the TX and 0.26 ± 0.06 in the DX groups and 2.19 ± 0.86 in the control. Statistically significant inhibition of root resorption was determined both in the TX and DX groups (P < 0.001) on the TM side. There was no statistically significant difference in relative root resorption between the TX and DX groups. Systemic administration of TX and DX demonstrated similar effects on root resorption in rats and may have inhibitory effects on orthodontically induced resorptive activity.