Long-term stability of mandibular incisor alignment in patients treated nonextraction with or without interproximal enamel reduction.

INTRODUCTION: This study aimed to compare long-term mandibular incisor stability in nongrowing patients with moderate crowding treated nonextraction with and without interproximal enamel reduction (IPR). METHODS: Forty-two nongrowing patients with Class I dental and skeletal malocclusion with moderate crowding were divided into 2 groups with an equal number of patients depending on whether IPR was used (IPR group) or not (non-IPR group) during treatment. All patients were treated by the same practitioner and used thermoplastic retainers full-time for 12 ± 1 months at the end of the active treatment. Changes in Peer Assessment Rating scores, Little's irregularity index (LII), intercanine width (ICW), and mandibular incisor inclination (IMPA and L1-NB°) were evaluated using pretreatment, posttreatment, and 8 ± 1 years postretention dental models and lateral cephalograms. RESULTS: At the end of the treatment, Peer Assessment Rating scores and LII decreased, and ICW, IMPA, and L1-NB° increased significantly (P <0.001) in both groups. At the end of the postretention period, in both groups, LII increased, and ICW decreased significantly (P <0.001) compared with posttreatment values, whereas IMPA and L1-NB remained stable. When treatment changes were compared, increases in ICW, IMPA, and L1-NB were significantly (P <0.001) higher in the non-IPR group. When postretention changes were compared, the only significant difference between 2 groups was observed in ICW. The decrease in ICW was significantly higher in the non-IPR group. CONCLUSIONS: Long-term stability of mandibular incisor alignment in Class I nongrowing patients with moderate crowding treated nonextraction with and without IPR was similar.

A practical formula for determining growth.

PURPOSE: We aimed to establish a practical method to evaluate skeletal age using cervical vertebrae. METHODS: The study consisted of hand-wrist and cephalometric radiographs of 324 subjects (167 girls, 157 boys; age range, 7.3-17.2 years). Skeletal ages of the subjects were calculated from hand-wrist radiographs, and cervical vertebral bodies were measured using cephalometric radiographs. A single formula based on C3 and C4 vertebral body heights with different coefficients for each gender was derived using ridge regression analysis. RESULTS: The correlation coefficients for vertebral and hand-wrist bone age were 0.825 and 0.856 for girls and boys, respectively. The correlations among vertebral bone age and C3 and C4 vertebral body heights were also found to be significant. The intraclass correlation (ICC) score was found to be 0.914, which shows high consistency between the two measurements of the same investigator for each C3 and C4 vertebral body height result. CONCLUSION: The formula derived for evaluating skeletal age in cephalometric radiographs is reliable and can be applied to both girl and boy subjects for legal requirements or therapeutic needs of age estimation.

Changes in airway dimensions and hyoid bone position following class II correction with forsus fatigue resistant device.

OBJECTIVE: The objective of this study was to investigate the effects of fixed functional therapy on oropharyngeal airway dimensions and hyoid bone positions in Class II patients and make comparison with an untreated Class II group. MATERIALS AND METHODS: Eighteen patients (8 girls, 10 boys; mean age 13.62 ± 1.92 years) who were treated with Forsus Fatique Resistant Device (FFRD) and 19 patients (11 girls, 8 boys; mean age 12.74 ± 0.91 years) who served as control were enrolled. Cephalograms were used to assess linear, angular, and area measurements. Intragroup comparisons were made by paired t and Wilcoxon tests and intergroup comparisons were performed by independent t test. RESULTS: With respect to controls, FFRD group showed increased airway dimensions at soft palate (P < 0.05) and more forward positioning of the hyoid bone (P < 0.05). Dentoalveolar changes exhibited mesial movement of lower incisors and molars and reduction in overjet (P < 0.001) in FFRD group. CONCLUSIONS: Positive effects in oropharyngeal airway dimensions and increased values of hyoid bone displacement to a more forward position were found after fixed functional therapy. CLINICAL RELEVANCE: Treatment with fixed functional appliances is mostly based on mesial movement of mandibular dentition, which might influence changes in tongue posture. The present results might indicate that oropharyngeal airway dimensions may be affected by postural changes of the hyoid bone in consequence of dentoalveolar changes. Clinically, these may be considered especially in Class II cases with reduced airway dimensions.

Effects of a newly designed orthodontic miniplate platform for elevating the miniplate over the gingiva: A 3-dimensional finite element analysis.

INTRODUCTION: Miniplates are the treatment of choice for complex orthodontic and orthopedic problems. However, they require surgical placement and removal, and complications such as infection and mobility can occur. The aim of this finite element analysis was to investigate the effects of a newly designed miniplate platform to elevate the miniplate above the gingiva. METHODS: A bone block was modeled in 3 dimensions, and 2 N of force was applied on miniplates in 2 scenarios. In scenario 1, the miniplate was fixed with 2 miniscrews on both ends; in scenario 2, miniplate platforms were first seated on the cortical bone surface with their spikes fully penetrating, and then the miniplate was fixed on top with 2 miniscrews. RESULTS: The highest von Mises stress on the cortical bone decreased from 0.5 to 0.3 MPa when miniplate platforms were used. In scenario 2, the principal maximum stresses on the cortical bone around the miniscrews decreased from 0.42 and 0.48 MPa to 0.20 and 0.22 MPa, and the principal minimum stresses decreased from -0.45 and -0.48 MPa to -0.01 MPa. CONCLUSIONS: Miniplate platforms used to elevate the miniplate lowered the stresses generated on cortical bone around the miniscrews by distributing the stresses on the cortical bone surface. Patients can clean the miniplate more readily because it is elevated above the soft tissues. Placing the miniplate platforms requires only removing the gingiva with a punch, and their removal does not require flap surgery.

Effects of reverse headgear on pharyngeal airway in patients with different vertical craniofacial features.

The aim of this study was to investigate the effects of reverse headgear (RH) on pharyngeal airway morphology in two groups of Class III patients with different vertical craniofacial features in comparison with an untreated Class III group. Seventeen subjects (9 males, 8 females; mean age 11.3 ± 0.98 years) with optimum vertical growth and 17 subjects (10 males, 7 females, mean age 11.5 ± 1.1 years) with a vertical growth pattern treated with a removable intra-oral appliance and a Delaire type facemask were included. An untreated Class III control group of 11 subjects (8 males, 3 females, mean age 9.1 ± 1.1 years) was included to compare the treated groups. The paired t-test for intragroup and one-way ANOVA for intergroup comparisons were performed. The relationships between changes in the craniofacial morphology and airway were assessed by Spearman correlation analysis. The airway dimensions at the adenoid side and soft palate were increased in the treatment groups compared to the control group (p < 0.05). The nasopharyngeal area demonstrated a significant difference in normodivergent and control subjects (p < 0.05). No significant difference was found in the airway morphology due to different vertical features. The effect of RH treatment on the sagittal airway dimensions revealed no significant difference between different vertical craniofacial features in the short term.

Evaluation of airway dimensions and changes in hyoid bone position following class II functional therapy with activator.

AIM: The aim of this study was to evaluate the long-term effects of Class 2 functional treatment on airway dimensions and positional changes in hyoid bone and compare it with that of an untreated Class 2 control group. METHODS: Lateral cephalograms of 16 patients (eight girls, eight boys, mean chronological age = 11.36 ± 0.77 years) who were treated with activator and 19 patients (11 girls, eight boys, mean chronological age = 12.14 ± 0.65 years) who served as control were used for linear, angular and area measurements regarding airway track and hyoid bone. Statistics. Intra-group comparisons were performed by paired t-test and Wilcoxon test, whereas independent t-test and Mann Whitney-U were used for inter-group comparisons. RESULTS: During treatment (T2-T1), nasopharyngeal height and nasopharyngeal area increased (p < 0.05) and hyoid bone moved downward (H-SN; p < 0.001) and forward (H-C3; p < 0.01). During retention period (T3-T2); nasopharyngeal (p < 0.01) and oropharyngeal area increased (p < 0.05). H-SN (p < 0.01) and C3-H distances (p < 0.05) increased. Hyoid bone position exhibited significant changes (H-SN, p < 0.001; C3-H, p < 0.01). The increases in C3-H in long-term was more in the activator group than control (p < 0.05). CONCLUSIONS: In growing Class 2 patients with mandibular deficiency and airway track without obstructions, functional appliance treatment provided favorable effects on nasopharyngeal and oropharyngeal area throughout the retention period.

Treatment effects of the Forsus Fatigue Resistant Device used with miniscrew anchorage.

OBJECTIVE: To evaluate the dentofacial effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage (FRDMS) and compare them with those of conventional FRD and an untreated Class II control group. MATERIALS AND METHODS: The sample consisted of 48 Class II subjects. Sixteen patients (13.68 ± 1.09 years of age) were treated with FRDMS, whereas 17 subjects (14.64 ± 1.56 years of age) were treated with only FRD. Also, a control sample of 15 untreated Class II subjects (14.13 ± 1.50 years of age) was constructed. Angular and linear measurements were made on 96 lateral cephalograms. Paired t, one-way analysis of variance, and Tukey tests were used for statistical analysis. RESULTS: Class I molar relationship and overjet correction were achieved in an average period of 6.5 ± 1.97 and 5.5 ± 1.80 months in the FRDMS and FRD groups, respectively. No skeletal effect was determined in both treatment groups. Greater overbite correction was found in the FRD group. Retrusion and extrusion of maxillary incisors, distalization of maxillary molars, and extrusion of mandibular molars were significant in both treatment groups. Labial tipping of mandibular incisors was significantly greater in the FRD group than in the FRDMS group. CONCLUSION: Overjet and molar correction was totally dentoalveolar. Unfavorable labial tipping of mandibular incisors was effectively minimized with the usage of miniscrews.

Deepbite correction with incisor intrusion in adults: a long-term cephalometric study.

INTRODUCTION: The purpose of this study was to investigate the long-term stability of deep overbite correction with mandibular incisor intrusion with utility arches in adult patients. METHODS: Pretreatment, posttreatment, and 5-years postretention lateral cephalograms of 31 patients (mean age, 26.8 years; range, 24.1-30.9 years) with Class II Division 1 malocclusion and deepbite, treated by maxillary first premolar extraction and mandibular incisor intrusion, were traced and measured. RESULTS: Significant decreases in overjet and overbite (6.4 ± 1.2 and 3.9 ± 0.7 mm, respectively), significant retroclination (17° ± 1.9°) and retraction (3.8 ± 1.1 mm) of the maxillary incisors, and significant increases in protrusion (0.8 ± 1.5 mm), proclination (0.6° ± 0.9°), and intrusion (2.6 ± 1.4 mm) of the mandibular incisors were observed at posttreatment. At postretention, there were statistically significant but clinically unimportant increases in overjet and overbite (0.4 ± 0.2 and 0.8 ± 0.4 mm, respectively) and extrusion of the mandibular incisors (0.8 ± 1.1 mm). CONCLUSIONS: Correction of deepbite in nongrowing patients by mandibular incisor intrusion with a utility arch can be considered effective and stable.

Effect of premolar extraction on mandibular third molar impaction in young adults.

OBJECTIVE: To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction. MATERIALS AND METHODS: Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated. RESULTS: Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm. CONCLUSIONS: When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.

Evaluation of different enamel conditioning techniques for orthodontic bonding.

OBJECTIVE: The aim of this study was to compare the effects of different enamel conditioning techniques for bracket bonding. METHODS: Ninety-one human premolars were randomly divided in six groups of 15 specimens each. The enamel surfaces of the teeth were etched with 35% orthophosphoric acid in Group 1, with a self-etching primer in Group 2, sandblasted in Group 3, sandblasted and etched with 35% orthophosphoric acid in Group 4, conditioned by Er:YAG laser in Group 5 and conditioned by Er:YAG laser and etched with 35% phosphoric acid gel respectively in Group 6. After enamel conditioning procedures, brackets were bonded and shear bonding test was performed. After debonding, adhesive remnant index scores were calculated for all groups. One tooth from each group were inspected by scanning electron microscope for evaluating the enamel surface characteristics. RESULTS: The laser and acid etched group showed the highest mean shear bond strength (SBS) value (13.61 ± 1.14 MPa) while sandblasted group yielded the lowest value (3.12 ± 0.61 MPa). CONCLUSIONS: Although the SBS values were higher, the teeth in laser conditioned groups were highly damaged. Therefore, acid etching and self-etching techniques were found to be safer for orthodontic bracket bonding. Sandblasting method was found to generate inadequate bonding strength.

Influence of thermoplastic retainers on Streptococcus mutans and Lactobacillus adhesion.

INTRODUCTION: This study was designed to test the hypothesis that thermoplastic retainers influence oral microbial flora during the retention period because they prevent the flushing effect of saliva on dental and mucous tissues. METHODS: Twenty-four orthodontic patients finished the study. After debonding, the patients were given thermoplastic retainers (Essix ACE 0.040-in plastic, Dentsply International, York, Pa) for both jaws and instructed to wear them all day. Plaque samples from tooth surfaces and saliva samples were collected from each patient just after debonding (T0), and on day 15 (T1), day 30 (T2), and day 60 (T3) of retention. The jaws were divided into 6 regions, and the data for each region were evaluated separately. Total viable Lactobacillus and Streptococcus mutans colonies were counted, and the numbers of the viable microorganisms were calculated. RESULTS: The numbers of Lactobacillus colonies at T3 were higher than at T0, T1, and T2, and the difference between T0 and T3 was statistically significant (P <0.05). The numbers of S mutans colonies at T3 were higher than at T0, T1, and T2, and the differences between T0 and T1, and T1 and T2 were statistically significant (P <0.05). CONCLUSIONS: Retention with thermoplastic retainers might create oral conditions conducive to S mutans and Lactobacillus colonization on dental surfaces.

Evaluation of extraction and non-extraction treatment effects by two different superimposition methods.

The aim of this study was to determine whether different evaluation methods may be the cause of the varied outcomes of research that have evaluated the effects of extraction and non-extraction therapy on jaw rotation. This retrospective study consisted of the pre- (T1) and post- (T2) treatment lateral cephalograms of 70 skeletal Class I subjects with an optimal vertical mandibular plane angle, who had undergone fixed orthodontic treatment. Thirty-five of the subjects (20 females and 15 males, mean age: 14.7 years) were treated with four first premolar extractions and 35 (22 females and 13 males, mean age: 15 years) without extractions. T1 and T2 radiographs were superimposed using Björk's structural method and Steiner's method of sella-nasion line registered at sella. A Wilcoxon test was used to evaluate the changes between T1 and T2 and the Mann-Whitney U-test to determine differences between the extraction and non-extraction and Björk and Steiner groups. No significant difference was found between the methods of Steiner and Björk according to the spatial changes of the cephalometric points in the extraction and non-extraction groups. The maxilla showed forward rotation in the extraction group and backward rotation in the non-extraction group with both superimposition methods, but the differences were not significant in either inter- or intraclass comparisons. The mandible showed forward rotation in the extraction group with both superimposition methods but, in the non-extraction group, forward rotation was recorded with Björk's method and backward rotation with Steiner's method. These findings were not significant in either inter- or intraclass evaluations. No significant difference was found between the groups or methods.

The effect of drill-free and drilling methods on the stability of mini-implants under early orthodontic loading in adolescent patients.

The aim of this study was to compare the stability of mini-implants using drill-free and drilling methods, both before and after early force loading. Sixty-two adolescent patients (24 males and 38 females, mean age 15.7 ± 4.2 years) were randomly assigned to three groups and 112 titanium mini-implants were placed between the upper first molars and second premolars to achieve molar distalization. Groups I (n = 22) and II (n = 20) received pilot drilling with diameters of 1.1 and 0.9 mm, respectively, while the drill-free method was used in group III (n = 20). Distalization forces of up to 200 g were applied with nickel-titanium (NiTi) open coil springs. The Z-test was used for statistical analyses to compare the success rates of the groups with each other. The overall success rate was 77.7 per cent. There was no significant difference between groups I and II either before or after loading. Significant differences were found between groups I and III (P = 0.0002) and between groups II and III (P = 0.045) both before and after loading. Mini-implants using the drill-free method provided the highest success rate before orthodontic force application and also maintained their stability after early loading for 1 month during orthodontic treatment. Smaller drill diameters can contribute to clinical stability of mini-implants in the short-term, however long-term evaluations are needed to clarify the stability of temporary skeletal anchorage devices throughout orthodontic loading.