Morphometric evaluation of changes in the alveolar bone and roots of the maxillary anterior teeth before and after en masse retraction using cone-beam computed tomography

OBJECTIVE

To evaluate the morphometric changes in the alveolar bone and roots of the maxillary anterior teeth (MXAT) after en masse retraction with maximum anchorage (EMR-MA).

MATERIALS AND METHODS

The samples consisted of 37 female adult patients who had Class I dentoalveolar protrusion (CI-DAP) and were treated by extraction of the first premolars and EMR-MA. Using three-dimensional cone-beam computed tomography taken before treatment and after space closure, the maxillary central incisors (MXCI, N  =  66), lateral incisors (MXLI, N  =  69), and canines (MXC, N  =  69) were superimposed using individual reference planes. After alveolar bone area (ABA), vertical bone level (VBL), root length (RL), root area (RA), and prevalence of dehiscence (PD) were measured at the cervical, middle, and apical levels, statistical analyses were performed.

RESULTS

On the palatal side, ABA significantly decreased in all levels of MXAT (P < .001; middle of MXC, P < .01). MXCI and MXLI exhibited a greater decrease in the ratio of change in palatal ABA than did MXC (cervical, P < .01; middle and apical, P < .05; total, P < .001). Palatal/labial ABA ratios decreased in MXCI (cervical, middle, total, P < .001; apical, P < .05) and MXLI (cervical, P < .001; apical, P < .05). They showed greater amounts and ratios of change in VBL on the palatal side compared to the labial side (all P < .001). The palatal side showed more PD in the cervical area than did the labial side (MXCI and MXLI, P < .001; MXC, P < .01). Significant root resorption occurred in MXAT (RL and RA, all P < .001).

CONCLUSIONS

During EMR-MA in cases with CI-DAP, ABA and VBL on the palatal side and RL and RA of MXCI and MXLI were significantly decreased.

Evaluation of miniscrew-supported rapid maxillary expansion in adolescents: A prospective randomized clinical trial

OBJECTIVES:

To evaluate and compare the dental and skeletal changes with conventional and miniscrew-supported maxillary expansion appliances in adolescents.

MATERIALS AND METHODS:

Forty patients were divided into two groups, with one group receiving a tooth-borne expander and the other group receiving an expander supported by four miniscrews (bone-borne). Multiplanar coronal and axial slices obtained from cone-beam computed tomography images were used to measure the changes in transverse skeletal widths, buccal bone thickness, tooth inclination, and root length. Paired t-tests and independent-sample t-tests were used to compare the two expansion methods.

RESULTS:

Bone-borne expansion increased the maxillary suture opening more than 2.5 times than tooth-borne expansion both anteriorly and posteriorly. Between the maxillary first premolars, sutural expansion accounted for 28% and 70% of the total transverse width increase in the tooth-borne and bone-borne expander groups, respectively. Similarly, 26% and 68% of the total expansion was of skeletal nature in the tooth-borne and bone-borne expander groups between the maxillary first molars. The pattern of expansion was variable, with most of the patients in both groups demonstrating a triangular-shaped sutural opening that was wider anteriorly. Subjects in the conventional group experienced significantly more buccal bone reduction and greater buccal inclination of the teeth. No significant differences were observed for root length measurements between the two groups.

CONCLUSION:

Use of bone-borne expansion in the adolescent population increased the extent of skeletal changes in the range of 1.5 to 2.8 times that of tooth-borne expansion and did not result in any dental side effects.

Distalization of maxillary molars with the bone-supported pendulum: A clinical study

A modified pendulum appliance with 2 endosseus screws for anchorage in the palatal area was used for maxillary molar distalization in each of 15 patients (average age, 13 +/- 2.1 years). Study models and lateral and panoramic x-rays were taken at the beginning and end of the movement to record the dental and skeletal changes. The mean treatment time was 7.8 +/- 1.7 months, the average distal movement of the maxillary molars was 6 mm, and the inclination was 11.3 degrees +/- 6.2 degrees. The second premolars were distalized an average of 4.85 +/- 1.96 mm with inclinations of 8.6 degrees +/- 5 degrees. The maxillary anterior teeth were retruded 0.5 +/- 1.33 mm and palatally inclined 2.5 degrees +/- 2.98 degrees. The mandibular plane rotated posteriorly 1.27 degrees +/- 1.1 degrees. No loss of dental anchorage was observed during the distal movement.

Nonextraction treatment of an open bite with microscrew implant anchorage

A 16-year-old girl with an anterior open bite was treated with nonextraction therapy that included intrusion of the maxillary and mandibular posterior teeth with microscrew implants. Implants (diameter, 1.2 mm; length, 8 or 6 mm) were placed into alveolar bone near the posterior teeth and used as anchorage for intrusive force. To prevent adverse side effects of buccoversion or linguoversion of the posterior teeth during intrusion, a transpalatal bar and a lingual arch were placed. The 3-mm anterior open bite was corrected in 11 months of treatment, after intrusion of the maxillary and mandibular posterior teeth and autorotation of the mandible. The posterior intrusion relapsed in the early stage of retention, at 8 months; thereafter, no obvious relapse was evident in the vertical position of the molars and the FMA. The treatment mechanics of anterior open bite with posterior intrusion by using microscrew implants were effective but still require a proper retention protocol.

Uvulo-glossopharyngeal dimensions in non-extraction, extraction with minimum anchorage, and extraction with maximum anchorage

The aim of this study was to investigate upper respiratory airway dimensions in non-extraction and extraction subjects treated with minimum or maximum anchorage. Lateral cephalograms of 39 Class I subjects were divided into three groups (each containing 11 females and 2 males) according to treatment procedure: group 1, 13 patients treated with extraction of four premolars and minimum anchorage; group 2, 13 cases treated non-extraction with air-rotor stripping (ARS); and group 3, 13 bimaxillary protrusion subjects treated with extraction of four premolars and maximum anchorage. The mean ages of the patients were 18.1 ± 3.7, 17.8 ± 2.4, and 15.5 ± 0.88 years, respectively. Tongue, soft palate, hyoid position, and upper airway measurements were made on pre- and post-treatment lateral cephalograms and the differences between the mean measurements were tested using Wilcoxon signed-ranks test. Superior and middle airway space increased significantly (P < 0.05) in group 1. In group 2, none of the parameters showed a significant change, while in group 3, middle and inferior airway space decreased (P < 0.01). The findings show that extraction treatment using maximum anchorage has a reducing effect on the middle and inferior airway dimensions.

Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults

OBJECTIVES

To evaluate changes in the volume and cross-sectional area of the nasal airway before and 1 year after nonsurgical miniscrew-assisted rapid maxillary expansion (MARME) in young adults.

MATERIALS AND METHODS

Fourteen patients (mean age, 22.7 years; 10 women, four men) with a transverse discrepancy who underwent cone beam computed tomography before (T0), immediately after (T1), and 1 year after (T2) expansion were retrospectively included in this study. The volume of the nasal cavity and nasopharynx and the cross-sectional area of the anterior, middle, and posterior segments of the nasal airway were measured and compared among the three timepoints using paired t-tests.

RESULTS

The volume of the nasal cavity showed a significant increase at T1 and T2 ( P < .05), while that of the nasopharynx increased only at T2 ( P < .05). The anterior and middle cross-sectional areas significantly increased at T1 and T2 ( P < .05), while the posterior cross-sectional area showed no significant change throughout the observation period ( P > .05).

CONCLUSIONS

The results demonstrate that the volume and cross-sectional area of the nasal cavity increased after MARME and were maintained at 1 year after expansion. Therefore, MARME may be helpful in expanding the nasal airway.

MMP-13 (collagenase 3) immunolocalisation during initial orthodontic tooth movement in rats

Matrix metalloproteinases (MMPs) are enzymes that play a central role in periodontal ligament (PDL) space remodelling during orthodontic tooth movement. It has previously been shown that messenger RNA levels of MMP-13 increase significantly following the application of orthodontic forces. The aim of the present study was to examine immunolocalisation of MMP-13 and to evaluate if this collagenase is time-dependently and differentially detected within the PDL following the application of orthodontic forces to create areas of compression and tension. This was achieved by placing elastic bands between the maxillary first and second molars of 16 male Sprague-Dawley rats (each weighing 120-200g) for 12 and 24h. The molar-bearing segments were dissected and processed for histological and immunohistochemical examination. Binding of a monoclonal antibody was used to evaluate MMP-13 localization using an indirect streptavidin/biotin immunperoxidase technique. MMP-13 was found to be inducible at the protein level by the application of forces. The PDL and osteoblast-lineage cells showed a time-dependent increase in immunolabelling of MMP-13. Immunolabelling of MMP-13 was detected initially on the compression side, and then on both the compression and the tension sides. Since this increase in MMP-13 immunolabelling occurred very early following the application of an orthodontic force in both PDL and alveolar bone, this would indicate that MMP-13 might play an important role during tooth movement.

Tumor Necrosis Factor–α Levels during Two Different Canine Distalization Techniques

Objectives: To compare levels of tumor necrosis factor (TNF)-α while applying continuous and heavy interrupted forces.

Materials and Methods: A hybrid retractor was used in the first group. In the second group, rapid canine distalization through periodontal distraction was performed. Gingival crevicular fluid samples were collected from the distal sides of the canine teeth before attaching the appliances and at 1 hour, 24 hours, and 1 week after the force was applied.

Results: In the hybrid reactor group, concentration of TNF-α decreased at 1 week according to 24-hour measurements. In the rapid canine distalization group, it severely increased at 1 hour. In the evaluation of between-group differences, significantly higher values were determined in the rapid canine distalization group at 1 hour and 1 week.

Conclusions: Heavy interrupted force induces a rapid release of TNF-α, and the tissue response continues for a longer time period. To avoid the harmful effects of heavy interrupted force, there might be feedback mechanisms that prevent the mediators from increasing excessively.

Arch width changes with a rapid maxillary expansion appliance anchored to the primary teeth

OBJECTIVE

To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage.

MATERIALS AND METHODS

Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3).

RESULTS

Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3.

CONCLUSION

To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.

Volumetric measurement of root resorption following molar mini-screw implant intrusion using cone beam computed tomography

Objective

Molar intrusion by mini-screw implantation can cause different degrees of root resorption. However, most methods (2-D and 3-D) used for evaluating root resorption have focused on the root length without considering 3-D resorption. The purpose of this study was to volumetrically evaluate root resorption using cone beam computed tomography(CBCT) after mini-screw implant intrusion.

Materials and Methods

1. The volumes of 32 teeth were measured using CBCT and laser scanning to verify the accuracy of CBCT. 2. Twelve overerupted molars from adult patients were investigated in this study. After mini-screw implants were inserted into the buccal and palatal alveolar bones, 150 g of force was applied to the mini-screw implants on each side to intrude the molars. CBCT images of all patients were taken immediately prior to intrusion and after intrusion. The volumes of the roots were calculated using the Mimics software program. The differences between the pre-intrusion and post-intrusion root volumes were statistically evaluated with a paired-samples t-test. In addition, the losses of the roots were statistically compared with each other using one-way analysis of variance at the P<0.05 level.

Results

No statistically significant volume differences were observed between the physical (laser scanning) and CBCT measurements (P>0.05). The overerupted molars were significantly intruded (P<0.05), and the average intrusion was 3.30±1.60 mm. The differences between the pre-intrusion and post-intrusion root volumes were statistically significant for all of the roots investigated (P<0.05). The roots were sorted by volume loss in descending order as follows: mesiobuccal, palatal, and distobuccal. Statistical significance was achieved among the three roots. The average total resorption for each tooth was 58.39±1.54 mm³.

Conclusion

Volume measurement using CBCT was able to effectively evaluate root resorption caused by mini-screw intrusion. The highest volume loss was observed in the mesiobuccal root among the three roots of the investigated first molar teeth.

Prediction of mandibular movement and its center of rotation for nonsurgical correction of anterior open bite via maxillary molar intrusion

OBJECTIVES

To evaluate quantitatively the relationship between molar intrusion (change [Δ] maxillary first molar [U6]-palatal plane [PP]) and changes in vertical and sagittal cephalometric parameters and to determine the center of mandibular autorotation.

MATERIALS AND METHODS

Twenty-one patients diagnosed with anterior open bite and successfully treated with molar intrusion (overbite [OB] > 0 mm) were retrospectively enrolled. Lateral cephalograms taken before and after molar intrusion were used to measure changes in vertical and sagittal cephalometric parameters. The center of mandibular autorotation was calculated by measuring displacement of gonion (Go) and pogonion (Pog). Paired t-tests were used to compare variables, and linear regression analysis was used to examine the relationship between ΔU6-PP and other variables.

RESULTS

The mandible exhibited counterclockwise rotation after maxillary molar intrusion, which led to closure of anterior open bite. Strong linear relationships, in descending order, between ΔU6-PP and ΔOB, Δanterior facial height (AFH), Δvertical reference plane (Pog), and Δsella-nasion to Go-menton (SN-GoMe), were observed. When the maxillary molar was intruded 1 mm, OB increased by 2.6 mm, AFH decreased by 1.7 mm, Pog moved forward by 2.3 mm, and SN-GoMe decreased by 2°. The center of mandibular autorotation was located 7.4 mm behind and 16.9 mm below condylion after molar intrusion.

CONCLUSIONS

The mandible exhibited counterclockwise rotation after maxillary molar intrusion; the center of mandibular autorotation was located behind and below condylion with individual variations.

Treatment outcomes of Class II malocclusion cases treated with miniscrew-anchored Forsus Fatigue Resistant Device: A randomized controlled trial

OBJECTIVE

To evaluate the skeletal, dental, and soft tissue effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage and compare them with those of the conventional Forsus FRD.

MATERIALS AND METHODS

This study was carried out on 38 patients. These patients were randomly allocated into three groups. The 14 patients in group 1 (aged 12.76 ± 1.0 years) were treated with the FRD appliance. In group 2, the 15 patients (aged 12.52 ± 1.12 years) received treatment with FRD using miniscrew anchorage, and the 9 patients in group 3 (aged 12.82 ± 0.9 years) received no treatment as a control group. Linear and angular measurements were made on lateral cephalograms before and immediately after Forsus treatment. Data were analyzed statistically using paired t-, ANOVA, and Tukey tests.

RESULTS

Class I molar relationship and overjet correction were achieved in both treatment groups. Although mandibular growth was statistically nonsignificant, there was a significant headgear effect on the maxilla. Mandibular incisor proclination, maxillary incisor retroclination, and distalization of maxillary molars were significant in both treatment groups. However, no significant differences were found between the treatment groups.

CONCLUSIONS

Class II correction was mainly dentoalveolar in both treatment groups. Use of miniscrews with Forsus did not enhance mandibular forward growth nor prevent labial tipping of the mandibular incisors.

Dentoalveolar and skeletal changes associated with the pendulum appliance followed by fixed orthodontic treatment

INTRODUCTION

This prospective clinical study analyzed the distalization of maxillary molars achieved by the pendulum appliance and its effect on the anchorage teeth during and after fixed orthodontic treatment.

METHODS

Lateral cephalograms of 22 adolescents (15 girls, 7 boys) taken pretreatment, after distalization, after leveling and aligning, and after fixed orthodontic treatment were evaluated. The initial mean age was 14.5 years (SD = 1.80). The mean time for distalization of the maxillary molars was 5.85 months (SD = 1.82), and the total treatment time was 3.61 years (SD = 1.83).

RESULTS

The pendulum appliance moved the maxillary molars distally, but with significant distal inclination, protrusion of the anterior teeth, and increase in lower anterior facial height (LAFH) due to the clockwise mandibular rotation. After fixed orthodontic treatment, the maxillary incisors and the maxillary first premolars and first molars were returned to their pretreatment anteroposterior positions. Thus, at postdistalization, there was 2.1 mm of protrusion of the maxillary first molars, despite the anchorage reinforcement (Nance button and cervical headgear worn at night during fixed appliance therapy). However, at the end of treatment, all patients had Class I molar relationships.

CONCLUSIONS

The pendulum appliance followed by fixed orthodontic treatment corrected the Class II sagittal relationship, especially due to the dentoalveolar changes secondary to the spontaneous mandibular growth in the anterior direction during fixed appliance treatment.

Bone availability for mandibular molar distalization in adults with mandibular prognathism

OBJECTIVES

To investigate the retromolar space available for molar distalization in patients with mandibular prognathism.

MATERIALS AND METHODS

Using cone-beam computed tomography, the posterior mandibular dimensions in 110 consecutive patients with Class I or Class III malocclusion were measured (mean age, 27.0 ± 7.1 years). The shortest linear distances from the distal root of the right mandibular second molar to the inner border of the mandibular cortex were measured at the level of root furcation and 2, 4, and 6 mm apical to the furcation along the sagittal line and the posterior line of occlusion. The retromolar distances were compared between the Class I and Class III malocclusion groups using general linear mixed models.

RESULTS

The retromolar space measured through the sagittal line showed no significant intergroup difference. Among the distances measured through the posterior line of occlusion, the space measured at depths 0 and 2 mm to the furcation were significantly greater in the Class III group than in the Class I group.

CONCLUSIONS

Patients with Class III malocclusion have greater retromolar space for mandibular molar distalization along the posterior line of occlusion only at the level of the second molar furcation.

Long-term stability of miniscrew anchored maxillary molar distalization in Class II treatment

OBJECTIVE

To investigate treatment stability of miniscrew-anchored maxillary distalization in Class II malocclusion.

MATERIALS AND METHODS

This retrospective study included a distalization (n = 19) and a control (n = 19) group; a patient group with minor corrections served the control. Lateral cephalograms of 38 adult patients were taken before (T0), immediately after (T1), and 3-4 years after (T2) treatment. Horizontal and vertical movement and tipping of the maxillary first molars (U6) and central incisors (U1) were measured along with skeletal craniofacial parameters at three time points to compare the two groups regarding the achieved treatment effects and their stability.

RESULTS

Total arch distalization therapy led to 4.2 mm of distal movement of U6 without distal crown tipping (0.6° of axis change) and 3.3° of occlusal plane steepening. Over an average retention period of 42 months, maxillary total arch distalization provided high stability of treatment results, showing the same amount of mesial movement (0.7 mm) as the control group.

CONCLUSIONS

In Class II treatment, miniscrew-anchored maxillary total arch distalization can provide stable distal movement of the maxillary first molars and central incisors.

Success rates of a skeletal anchorage system in orthodontics: A retrospective analysis

OBJECTIVES

To evaluate the premise that skeletal anchorage with SAS miniplates are highly successful and predictable for a range of complex orthodontic movements.

MATERIALS AND METHODS

This retrospective cross-sectional analysis consisted of 421 bone plates placed by one clinician in 163 patients (95 female, 68 male, mean age 29.4 years ± 12.02). Simple descriptive statistics were performed for a wide range of malocclusions and desired movements to obtain success, complication, and failure rates.

RESULTS

The success rate of skeletal anchorage system miniplates was 98.6%, where approximately 40% of cases experienced mild complications. The most common complication was soft tissue inflammation, which was amenable to focused oral hygiene and antiseptic rinses. Infection occurred in approximately 15% of patients where there was a statistically significant correlation with poor oral hygiene. The most common movements were distalization and intrusion of teeth. More than a third of the cases involved complex movements in more than one plane of space.

CONCLUSIONS

The success rate of skeletal anchorage system miniplates is high and predictable for a wide range of complex orthodontic movements.

Comparison of anterior and posterior mini-implant-assisted maxillary incisor intrusion: Root resorption and treatment efficiency

OBJECTIVE

To compare, through cone-beam computed tomography (CBCT), the root resorption and treatment efficiency of two different mini-implant-assisted modalities in intruding the maxillary incisors.

MATERIALS AND METHODS

Thirty-two adults who had deep bite and elongated maxillary incisors were randomly allocated to two groups: anterior mini-implant group (AMG) and posterior mini-implant group (PMG). In the AMG, approximately 40 g of force was applied per side with elastic chains from mini-implants placed between the lateral incisors and canines and in the PMG, with beta-titanium wires from mini-implants placed between the second premolars and first molars. This study was conducted on CBCT scans taken before intrusion and after 4 months of intrusion. Data were analyzed by means of a paired t-test, independent t-test, and Pearson's correlation test.

RESULTS

One patient was excluded from the AMG due to mini-implant loosening. While the incisors showed a significant reduction in length and volume, this amount was greater in the AMG, especially in the central incisors (P < .05). Together with the mean intrusion rates of 0.62 and 0.39 mm/mo in the AMG and PMG respectively, the center of resistance of the incisors showed distal movement with labial tipping; these changes were greater in the PMG (P < .001). Volumetric root resorption was correlated with the amount of intrusion (P < .05).

CONCLUSIONS

Intrusion anchoring from posterior mini-implants is preferred in cases of upright incisors, as the use of such mechanics directs the roots into the spongiosa where they undergo less root resorption and more labial tipping.

An Umbrella Review of the Effectiveness of Temporary Anchorage Devices and the Factors That Contribute to Their Success or Failure

OBJECTIVES

New methodological approaches, such as the umbrella review, constitute an important pathway for synthesizing the scientific evidence provided from studies with a high level of evidence. This study aims to summarize the results on the effectiveness of temporary anchorage devices (TADs) and the factors that contribute to their success or failure during orthodontic treatment in patients of different age groups and to identify the gaps in knowledge based on analysis of the scientific literature.

METHODS

An umbrella review of systematic reviews and meta-analyses was performed. A quality evaluation and a descriptive analysis of the included studies were conducted. The study protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO: CRD42018094463).

RESULTS

Seventeen systematic reviews and meta-analyses were considered (10 descriptive and 7 with meta-analysis; 12 of high quality and 5 of moderate quality). Variability was observed in the type of intervention and the type of system (TADs). Most of the studies reported high success rates (≥90%), and just one systematic review indicated a low rate of success (≤56%) for the mini-screws. All the studies discussed several factors related to the success of the TADs. These factors were classified as device-related factors, patient-related factors, procedure-related factors, and orthodontic treatment-related factors. Conceptual and methodological gaps were observed when considering the data analysis, the terminology used, and the orthodontic protocols.

CONCLUSIONS

The results should be analysed cautiously because of several research gaps related to the methodological quality and the high heterogeneity of the original studies and because of the necessity to add several clinical and sociodemographic variables to enrich the data analysis.

Mandibular and glenoid fossa changes after bone-anchored maxillary protraction therapy in patients with UCLP: A 3-D preliminary assessment

OBJECTIVE

To assess mandibular and glenoid fossa (GF) changes after bone-anchored maxillary protraction (BAMP) therapy in patients with unilateral complete cleft lip and palate (UCLP).

MATERIALS AND METHODS

The cleft group (CG) comprised 19 patients with (mean initial age of 11.8 years). The noncleft group (NCG) comprised 24 patients without clefts (mean initial age of 11.7 years). Both groups had Class III malocclusion and were treated with BAMP therapy for 18 and 12 months, respectively. Cone-beam computed tomography (CBCT) exams were performed before and after treatment and superimposed on the anterior cranial fossa (ACF). Mandibular rotations and three-dimensional linear displacements of the mandible and GF were quantified. A t-test corrected for multiple testing (Holm-Bonferroni method) and a paired t-test were used to compare, respectively, the CG and NCG and cleft vs noncleft sides (P < .05).

RESULTS

Immediately after active treatment, the GF was displaced posteriorly and laterally in both groups relative to the ACF. The overall GF changes in the CG were significantly smaller than in the NCG. Condylar displacement was similar in both groups, following a posterior and lateral direction. The gonial angle was displaced similarly posteriorly, laterally, and inferiorly in both groups. The intercondylar line rotated in opposite directions in the CG and NCG groups. In the CG, most changes of the GF and mandible were symmetrical.

CONCLUSIONS

Overall GF and mandibular changes after BAMP therapy were similar in patients with and without clefts. The exception was the posterior remodeling of the GF that was slightly smaller in patients with UCLP.

Total arch maxillary distalization using infrazygomatic crest miniscrews in the treatment of Class II malocclusion: a prospective study

OBJECTIVES

To evaluate treatment effects in Class II patients using infrazygomatic crest (IZC) miniscrews (MS).

MATERIALS AND METHODS

A prospective sample of 25 adolescents (14 females and 11 males; mean age: 13.6 ± 1.5 years) who underwent maxillary dentition distalization treatment with IZC MSs were recruited. Lateral cephalograms and digital models at the beginning of treatment (T1) and after Class II molar correction (T2) were obtained. To compare cephalometric and digital model changes, paired t-test and Wilcoxon test were used. A significance level of 5% was used.

RESULTS

All patients achieved Class II molar correction over a mean period of 7.7 ± 2.5 months. The IZC MS therapy provided 4 mm of distalization; there was 1.2 mm of intrusion of the first molar with 11.2° distal tipping. The maxillary incisors were retracted 4.7 mm and tipped lingually 13.4°. Overjet and overbite showed a reduction of 3.6 mm and 2.4 mm, respectively. The occlusal plane rotated clockwise 2.8°. The upper lip was retracted by 1 mm and the nasolabial angle increased 5.1°. There was an increase in the interpremolar and intermolar distances.

CONCLUSIONS

Total arch distalization of the maxillary dentition using IZC MS was effective in the treatment of Class II malocclusions.

Comparison of orthodontic tooth movement between adolescents and adults based on implant superimposition

OBJECTIVE

We compared tooth movement under maximum anchorage control with mini-screw implants in growing and non-growing patients.

METHODS

In total, 15 adolescent (G1) and 19 adult (G2) patients with prognathic profiles were selected. All patients underwent first premolar extraction treatment with mini-screw implants for maximum anchorage control. Cone-beam computed tomography (CBCT) data were obtained immediately after implant placement (T1) and at the end of anterior tooth retraction (T2). Tooth movement and root length changes of the maxillary first molar, canine, and incisors were evaluated with three-dimensional models constructed using CBCT data obtained before and after orthodontic retraction through the superimposition of stable implants.

RESULTS

Distal movement of the molar crown was observed in G2, but mesial movement was observed in G1. Mesial tipping of the first molar (1.82 ± 6.76°) was seen in G1 and distal tipping (4.44 ± 3.77°) was observed in G2. For the canines, mesial crown tipping (0.33 ± 4.99°) was noted in G1 and distal crown tipping (8.00 ± 5.57°) was observed in G2. In adults, the lingual inclinations of the lateral and central incisors were 11.91 ± 7.01° and 11.47 ± 6.70°, with 0.99 ± 1.22 mm and 1.08 ± 1.20 mm root retraction, respectively. In adolescents, the torque changes were smaller (lateral incisors, 8.25 ± 10.15°; central incisors, 9.82 ± 8.97°) and the root retractions were 0.31 ± 1.81 mm and 0.77 ± 1.59 mm, respectively. Less shortening of the central incisor roots occurred in adolescents than in adults.

CONCLUSIONS

Tooth movements, such as anchor molar angular change, the canine tipping pattern, and the amount of incisor retraction, differed between adolescents and adults treated using the same anchorage with mini-screw implants, bracket prescription, and en masse retraction method. Anchorage strength of the first molars, canine movement patterns, and incisor retraction ranges are not determined by the anchorage device alone; growth and alveolar limitations also play roles.

Accuracy of digital workflow for placing orthodontic miniscrews using generic and licensed open systems. A 3d imaging analysis of non-native .stl files for guided protocols

BACKGROUND

This study aimed to assess the accuracy of digital workflow for guided insertion of miniscrews in the anterior palate using restorative implant dentistry software and licensed software for orthodontic applications.

METHODS

Twenty subjects (8 males, 12 females, mean age = 16.7 ± 2.1 years) were prospectively selected to receive guided insertion of bicortical palatal miniscrews. Virtual planning was performed using restorative implant dentistry software (Blue Sky Plan*, version 4.7) (group 1 = 10 subjects) and licensed orthodontic software (Dolphin Imaging Software, version 11.0) (group 2 = 10 subjects). A specific 3D Imaging technology was applied to permit the registration of the planned and achieved position of the miniscrews based on the superimposition of maxillary models. The angular deviation (accuracy error) between the planned and the achieved positions of the miniscrews were recorded. Independent Student's test was used with statistical significance set at p value < 0.05.

RESULTS

The mean accuracy error recorded in group 1 was 7.15° ± 1.09 (right side) and 6.19 ± 0.80 (left side) while the mean error in group 2 was 6.74° ± 1.23 (right side) and 5.79 ± 0.95 (left side). No significant differences were recorded between the two groups (p > 0.05); instead, miniscrews placed on the right side were almost one degree higher than the left side (p < 0.05) in both groups.

CONCLUSIONS

The clinical accuracy error was similar when using generic and licensed orthodontic software for guided systems.

Pain and discomfort following insertion of miniscrews and premolar extractions: A randomized controlled trial

OBJECTIVE

To investigate and compare the experience of pain and discomfort between insertion of miniscrews and premolar extractions in adolescent patients.

MATERIALS AND METHODS

A total of 80 adolescents were recruited and randomized into groups A and B. Both groups were treated with extraction of the upper first premolars and fixed appliance. Beyond the fixed appliance, patients in group A received anchorage reinforcement with miniscrews. Miniscrews were inserted buccally between the second premolar and first molar when space closure started. Space closure was performed as en masse retraction with immediate loading by 150-g coil springs. Pain, discomfort, impact on daily activities, and functional jaw impairment were assessed with patient-reported questionnaires. Questionnaires were filled in at baseline, the evening after tooth extraction, 1 week after tooth extraction, the evening after screw placement, and 1 week after screw placement.

RESULTS

Patients reported significantly lower levels of pain (P < .001) and discomfort (P = .012) after screw placement compared with premolar extractions. The ability to drink (P = .035) and the ability to take a big bite (P < .001) were also significantly less disturbed in the evening after screw placement. During the first week after screw placement, the impact on leisure time activities was significantly lower (P = .015) compared with premolar extractions.

CONCLUSION

The use of miniscrews in adolescents can be recommended from a pain and discomfort perspective.

Survival estimates and risk factors for failure of palatal and buccal mini-implants

OBJECTIVES

The primary objective was to compare the success and survival rates of palatal and buccal mini-implants for different locations and treatment requirements. The secondary objective was to evaluate risk factors influencing the survival of mini-implants.

MATERIALS AND METHODS

In this retrospective cohort, records of 127 orthodontic patients with 257 mini-implants were included after imposing inclusion/exclusion criteria. Along with the implant failure data, factors such as age, sex, transverse location, anteroposterior location, and purpose of mini-implants were recorded. Kaplan-Meier survival analysis was used to draw the curves and a Nathan Mantel-David Cox test to compare variables.

RESULTS

The failure rate of palatal mini-implants was 8.5%, whereas the failure rate for buccal shelf mini-implants was 68.7% (P < .0001). A significant difference was that the survival rates of palatal mini-implants were dependent on the purpose of the mini-implants and, for the buccal mini-implants, they were dependent on the skeletal malocclusion and location type of mini-implants (P < .05).

CONCLUSIONS

The overall survival rate of palatal mini-implants was high, at 91.5%. Of the buccal mini-implants, inter-radicular mini-implants had the highest survival rate for 12 (75.5%) and 24 (71.9%) months, while buccal shelf mini-implants had the lowest success and survival rates for 12 (31.3%) and 24 (20.8%) months. Class III malocclusion had the lowest survival rate for the buccal mini-implants (65.3% and 54.2%) for 12 and 24 months.

Insertion torque, pull-out strength and cortical bone thickness in contact with orthodontic mini-implants at different insertion angles

This study aimed to evaluate biomechanical behaviour of inclined orthodontic mini-implants by analyzing its insertion torque (IT), axial pull-out strength (APS), and cortical bone thickness in contact with mini-implant (CBTC). A total of 102 mini-implants were inserted at 90 degree, 60 degree, and 45 degree to the surface of synthetic bone. Peak IT was measured, and the mini-implants were aligned with the mechanical testing machine to record the APS. The cortical bone thickness in contact with each mini-implant was measured after the pull-out test and the data were subjected to statistical analyses. The 45 degree group had a significantly higher IT compared with the 90 degree group (P < 0.05). There was a statistically significant increase in the average of cortical bone thickness in CBTC across the three groups (P < 0.05). A negative correlation between the angulation and the CBTC (r = -0.95, P < 0.05) and a positive correlation between the APS and the CBTC were observed (r = 0.34, P < 0.05). Mini-implants that are inserted more inclined to the surface of the bone provide greater IT and an increased contact with the cortical bone. The greater the CBTC, the greater is the APS.