Differences in mandibular condyle and glenoid fossa morphology in relation to vertical and sagittal skeletal patterns: A cone-beam computed tomography study.

OBJECTIVE: This study aimed to evaluate the following null hypothesis: there are no differences in the morphology of the temporomandibular joint (TMJ) structures in relation to vertical and sagittal cephalometric patterns. METHODS: This retrospective study was performed with 131 participants showing no TMJ symptoms. The participants were divided into Class I, II, and III groups on the basis of their sagittal cephalometric relationships and into hyperdivergent, normodivergent, and hypodivergent groups on the basis of their vertical cephalometric relationships. The following measurements were performed using cone-beam computed tomography images and compared among the groups: condylar volume, condylar size (width, length, and height), fossa size (length and height), and condyle-to-fossa joint spaces at the anterior, superior, and posterior condylar poles. RESULTS: The null hypothesis was rejected. The Class III group showed larger values for condylar width, condylar height, and fossa height than the Class II group (p < 0.05). Condylar volume and superior joint space in the hyperdivergent group were significantly smaller than those in the other two vertical groups (p < 0.001), whereas fossa length and height were significantly larger in the hyperdivergent group than in the other groups (p < 0.01). The hypodivergent group showed a greater condylar width than the hyperdivergent group (p < 0.01). The sagittal and vertical cephalometric patterns showed statistically significant interactions for fossa length and height. CONCLUSIONS: TMJ morphology differed across diverse skeletal cephalometric patterns. The fossa length and height were affected by the interactions of the vertical and sagittal skeletal patterns.

Miniscrew-assisted rapid palatal expansion: A review of recent reports.

The miniscrew-assisted rapid palatal expander (MARPE) has extended not only skeletal effects with fewer dental changes and but also the age limit of nonsurgical maxillary expansion treatment. Amid its gaining popularity in clinical orthodontics, our current understanding of treatment effectiveness, efficiency, and stability needs to be reassessed. In this review article, the authors have attempted to evaluate MARPE from various aspects with a focus on recent studies.

Stability of bimaxillary surgery involving intraoral vertical ramus osteotomy with or without presurgical miniscrew-assisted rapid palatal expansion in adult patients with skeletal Class III malocclusion.

OBJECTIVE: The aim of this study was to evaluate the stability of bimaxillary surgery involving bilateral intraoral vertical ramus osteotomy performed with or without presurgical miniscrew-assisted rapid palatal expansion (MARPE) in adult patients with skeletal Class III malocclusion. METHODS: A total of 40 adult patients with skeletal Class III malocclusion were retrospectively divided into two groups (n = 20 each) according to the use of MARPE for the correction of transverse maxillomandibular discrepancy during presurgical orthodontic treatment. Serial lateral cephalograms and dental casts were analyzed until 6 months after surgery. RESULTS: Before presurgical orthodontic treatment, there was no significant differences in terms of sex and age between groups. However, the difference of approximately 3.1 mm in the maxillomandibular intermolar width was statistically significant (p < 0.001). Two days after surgery, the mandible had moved backward and upward without any significant intergroup difference. Six months after surgery, the maxillary intercanine (2.7 ± 2.1 mm), interpremolar (3.6 ± 2.4 mm), and intermolar (2.0 ± 1.3 mm) arch widths were significantly increased (p < 0.001) relative to the values before presurgical orthodontic treatment in the MARPE group; these widths were maintained or decreased in the control group. However, there was no significant difference in surgical changes and the postsurgical stability between the two groups. No significant correlations existed between the amount of maxillary expansion and postsurgical mandibular movement. CONCLUSIONS: MARPE is useful for stable and nonsurgical expansion of the maxilla in adult patients with skeletal Class III malocclusion who are scheduled for bimaxillary surgery.

Positional changes in the mandibular proximal segment after intraoral vertical ramus osteotomy: Surgery-first approach versus conventional approach.

OBJECTIVE: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. METHODS: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. RESULTS: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. CONCLUSIONS: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

Comprehensive orthodontic treatment of a young girl with an odontogenic keratocyst and impacted teeth in the mandible.

Odontogenic keratocysts (OKCs) are one of the most aggressive cysts in the oral and maxillofacial area because of their high recurrence rate and infiltrative behavior. In growing patients with OKCs, a radical treatment approach might cause numerous complications, including the disturbance of jaw growth and loss of the involved tooth. This case report describes successful comprehensive orthodontic treatment combined with marsupialization of the cyst in a young girl who exhibited an OKC with impacted teeth. The 10-year-old girl presented with an OKC extending from the mandibular symphysis through the left mandibular body, with ectopic impaction of the mandibular left canine and first premolar, as well as congenitally missing bilateral mandibular second premolars. Interestingly, spontaneous improvement of the positions of the ectopic impacted teeth, along with a reduction in the size of the cyst, occurred during marsupialization. The sequential use of removable and fixed appliances enabled orthodontic traction of the impacted teeth. The treatment outcome was stable at 2.5 years after the end of the treatment. We speculate that comprehensive orthodontic treatment combined with marsupialization can be an effective treatment strategy for patients with OKCs, especially when they are encountered in young, growing patients with impacted teeth.

Diagnosis and Surgical Outcomes of Facial Asymmetry According to the Occlusal Cant and Menton Deviation.

PURPOSE: Morphologic differences and surgical outcomes were compared between the ipsilateral type of facial asymmetry, in which the menton deviates to the side of the upward frontal occlusal plane (FOP) cant (FOPUP), and the contralateral type, in which the menton deviates to the side of the downward FOP cant (FOPDOWN), by using cone beam computed tomography (CBCT) images. MATERIALS AND METHODS: This retrospective study included consecutive patients with skeletal Class III malocclusion and facial asymmetry who had undergone bimaxillary orthognathic surgery and serial CBCT before, 1 month after, and 1 year after surgery. CBCT images were reconstructed and analyzed for predictor (group and timing) and outcome (CBCT measurements over time) variables. The data were analyzed using independent t tests and paired t tests. RESULTS: The contralateral group (n = 12) was selected first; the ipsilateral group (n = 12) was selected by matching age, gender, and degree of FOP cant with those of the contralateral group. Before surgery, in the ipsilateral group, the ramal length was longer on the nondeviated (N-Dev) side than on the deviated (Dev) side (P < .05) whereas the mandibular body length showed no significant difference (P > .05). In the contralateral group, the ramal length was longer on the Dev side (P < .05) whereas the mandibular body length was longer on the N-Dev side (P < .01). One year after surgery, most measurements were corrected symmetrically in both groups (P > .05); however, the hemi-lower facial area remained asymmetrical in the contralateral group (P < .05). CONCLUSIONS: Differences in ramal lengths in the ipsilateral group and mandibular body lengths in the contralateral group between the Dev and N-Dev sides seemed to be the main cause of facial asymmetry. Although facial asymmetry improved after surgery in both groups, asymmetry in the soft tissue remained in the contralateral group 1 year after surgery.

Three-dimensional computed tomography analysis of mandibular morphology in patients with facial asymmetry and mandibular retrognathism.

INTRODUCTION: The purpose of this study was to analyze the morphologic features of skeletal units in the mandibles of patients with facial asymmetry and mandibular retrognathism using cone-beam computed tomography. METHODS: The subjects consisted of 50 adults with facial asymmetry and mandibular retrognathism, divided into the symmetry group (n = 25) and the asymmetry group (n = 25) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with cone beam computed tomography. Landmarks were designated on the reconstructed 3-dimensional images. Linear and volumetric measurements were made on the mandibles. RESULTS: In the asymmetry group, the lengths of condylar, body, and coronoid units were shorter, and condylar width was narrower on the deviated side than on the nondeviated side (P <0.01). The lengths of angular and chin units were not significantly different between the deviated and nondeviated sides (P >0.05). Hemimandibular, ramal, and body volumes were less on the deviated side than on the nondeviated side (P <0.01). CONCLUSIONS: Condylar, body, and coronoid units contribute to mandibular asymmetry in patients with facial asymmetry and mandibular retrognathism.

Precision and trueness of dental models manufactured with different 3-dimensional printing techniques.

INTRODUCTION: In this study, we assessed the precision and trueness of dental models printed with 3-dimensional (3D) printers via different printing techniques. METHODS: Digital reference models were printed 5 times using stereolithography apparatus (SLA), digital light processing (DLP), fused filament fabrication (FFF), and the PolyJet technique. The 3D printed models were scanned and evaluated for tooth, arch, and occlusion measurements. Precision and trueness were analyzed with root mean squares (RMS) for the differences in each measurement. Differences in measurement variables among the 3D printing techniques were analyzed by 1-way analysis of variance (α = 0.05). RESULTS: Except in trueness of occlusion measurements, there were significant differences in all measurements among the 4 techniques (P <0.001). For overall tooth measurements, the DLP (76 ± 14 µm) and PolyJet (68 ± 9 µm) techniques exhibited significantly different mean RMS values of precision than the SLA (88 ± 14 µm) and FFF (99 ± 14 µm) techniques (P <0.05). For overall arch measurements, the SLA (176 ± 73 µm) had significantly different RMS values than the DLP (74 ± 34 µm), FFF (89 ± 34 µm), and PolyJet (69 ± 18 µm) techniques (P <0.05). For overall occlusion measurements, the FFF (170 ± 55 µm) exhibited significantly different RMS values than the SLA (94 ± 33 µm), DLP (120 ± 28 µm), and PolyJet (96 ± 33 µm) techniques (P <0.05). There were significant differences in mean RMS values of trueness of overall tooth measurements among all 4 techniques: SLA (107 ± 11 µm), DLP (143 ± 8 µm), FFF (188 ± 14 µm), and PolyJet (78 ± 9 µm) (P <0.05). For overall arch measurements, the SLA (141 ± 35 µm) and PolyJet (86 ± 17 µm) techniques exhibited significantly different mean RMS values of trueness than DLP (469 ± 49 µm) and FFF (409 ± 36 µm) (P <0.05). CONCLUSIONS: The 3D printing techniques showed significant differences in precision of all measurements and in trueness of tooth and arch measurements. The PolyJet and DLP techniques were more precise than the FFF and SLA techniques, with the PolyJet technique having the highest accuracy.

Effects of bodily retraction of mandibular incisors versus mandibular setback surgery on pharyngeal airway space: A comparative study.

OBJECTIVE: The purpose of this study was to compare the changes induced in the pharyngeal airway space by orthodontic treatment with bodily retraction of the mandibular incisors and mandibular setback surgery without extraction. METHODS: This retrospective study included 63 adult patients (32 men and 31 women). Thirty-three patients who had been treated via four-bicuspid extraction and bodily retraction of the mandibular incisors (incisor retraction, IR group) were compared with 30 patients who had been treated via mandibular setback surgery (MS group) without extraction. Lateral cephalograms were acquired and analyzed before (T1) and after treatment (T2). RESULTS: The superior pharyngeal airway space did not change significantly in either group during treatment. The middle pharyngeal airway space decreased by 1.15 ± 1.17 mm and 1.25 ± 1.35 mm after treatment in the IR and MS groups, respectively, and the decrease was comparable between the two groups. In the MS group, the inferior pharyngeal airway space (E-IPW) decreased by 0.88 ± 1.67 mm after treatment (p < 0.01). The E-IPW was larger in the MS group than in IR group at T1, but it did not differ significantly between the two groups at T2. No significant correlation was observed between changes in the pharyngeal airway space and the skeletal and dental variables in each group. CONCLUSIONS: The middle pharyngeal airway space decreased because of the posterior displacement of the mandibular incisors and/or the mandibular body. The E-IPW decreased only in the MS group because of the posterior displacement of only the mandibular body.

Three-Dimensional Analysis of Midfacial Soft Tissue Changes After Maxillary Posterior Impaction and Intraoral Vertical Ramus Osteotomy for Mandibular Setback in Class III Patients.

This study investigated the correlation between the 3-dimensional changes in midfacial soft tissues, including the parasagittal area and maxilla-mandible complex, after Le Fort I maxillary posterior impaction and bilateral intraoral vertical ramus osteotomy (B-IVRO), using cone-beam computed tomography (CBCT). This retrospective study included 22 skeletal Class III patients (6 men and 16 women; mean age 21.6 years) who underwent orthognathic surgery. Three-dimensional CBCT images taken before and 1 year after surgery were superimposed based on the cranial base. Midfacial soft tissues, including those in the parasagittal area (paranasal area, anterior cheek area, lateral cheek area) and midsagittal areas of the face, were evaluated using reconstructed CBCT images. Correlations and the ratios between soft tissue and hard tissue movement were calculated. After surgery, both paranasal areas showed significant forward movement (about 2.0 mm) and the largest upward movement (about 0.15 mm) among the 3 areas. The paranasal areas moved forward with a ratio of 0.5, according to vertical movement of B. Orthognathic surgery using Le Fort I maxillary posterior impaction with B-IVRO mandibular setback results in forward movement of midfacial soft tissues, even though sagittal movement of the maxilla is limited because facial muscles and retaining ligaments pull the redundant soft tissues, which are caused by vertical movement of the maxilla-mandible. This midfacial soft tissue change with maxillary posterior impaction could be advantageous to patients who have paranasal depression and protrusion of the upper lip owing to proclined upper incisors, which are prevalent among Asian Class III patients.

Repeated injections of botulinum toxin into the masseter muscle induce bony changes in human adults: A longitudinal study.

OBJECTIVE: To evaluate soft- and hard-tissue changes in the mandibular angle area after the administration of botulinum toxin type A (BoNT-A) injection to patients with masseteric hypertrophy by using three-dimensional cone-beam computed tomography (3D-CBCT). METHODS: Twenty volunteers were randomly divided into two groups of 10 patients. Patients in group I received a single BoNT-A injection in both masseter muscles, while those in group II received two BoNT-A injections in each masseter muscle, with the second injection being administered 4 months after the first one. In both groups, 3D-CBCT was performed before the first injection and 6 months after the first injection. RESULTS: Masseter muscle thicknesses and cross-sectional areas were significantly reduced in both groups, but the reductions were significantly more substantial in group II than in group I. The intergonial width of the mandibular angle area did not change significantly in either group. However, the bone volume of the mandibular gonial angle area was more significantly reduced in group II than in group I. CONCLUSIONS: The repeated administration of BoNT-A injections may induce bone volume changes in the mandibular angle area.

Transport distraction osteogenesis combined with orthodontic treatment in a patient with unilateral temporomandibular joint ankylosis.

Temporomandibular joint ankylosis manifests a range of clinical characteristics dependent upon the age of onset, the affected side, and the severity. When it occurs during development, mandibular growth is affected, resulting in severe retrusion or asymmetry as well as limitation of mandibular movements. Progressive asymmetric mandibular growth in unilateral ankylosis causes canting of the occlusal plane. In this case report, we present a successful temporomandibular joint reconstruction using transport distraction osteogenesis combined with camouflage orthodontic treatment for occlusal canting correction of a patient with unilateral temporomandibular joint ankylosis and severe facial asymmetry.

Evaluation of stability after pre-orthodontic orthognathic surgery using cone-beam computed tomography: A comparison with conventional treatment.

OBJECTIVE: The aim of this study was to evaluate the skeletal and dental changes after intraoral vertical ramus osteotomy (IVRO) with and without presurgical orthodontics by using cone-beam computed tomography (CBCT). METHODS: This retrospective cohort study included 24 patients (mean age, 22.1 years) with skeletal Class III malocclusion who underwent bimaxillary surgery with IVRO. The patients were divided into the preorthodontic orthognathic surgery (POGS) group (n = 12) and conventional surgery (CS) group (n = 12). CBCT images acquired preoperatively, 1 month after surgery, and 1 year after surgery were analyzed to compare the intergroup differences in postoperative three-dimensional movements of the maxillary and mandibular landmarks and the changes in lateral cephalometric variables. RESULTS: Baseline demographics (sex and age) were similar between the two groups (6 men and 6 women in each group). During the postsurgical period, the POGS group showed more significant upward movement of the mandible (p < 0.05) than did the CS group. Neither group showed significant transverse movement of any of the skeletal landmarks. Moreover, none of the dental and skeletal variables showed significant intergroup differences 1 year after surgery. CONCLUSIONS: Compared with CS, POGS with IVRO resulted in significantly different postsurgical skeletal movement in the mandible. Although both groups showed similar skeletal and dental outcomes at 1 year after surgery, upward movement of the mandible during the postsurgical period should be considered to ensure a more reliable outcome after POGS.

Changes in the craniofacial complex and alveolar bone height of young adults: Applications to dental medicine.

The few studies on craniofacial complex changes in adults have reported contradictory findings. The aim of this study was to radiographically evaluate changes in the craniofacial complex and alveolar bone height of young adults over a 4-year period. This prospective study included 82 young adults (62 men; mean age, 19.0 ± 0.8 years; 20 women; mean age, 18.8 ± 0.9 years). Three radiographic examinations were performed longitudinally: the first (T0) was conducted at the start of the study, the second (T1) was conducted 2 years later, and the third (T2) was conducted at the end of the study period. As part of these examinations, lateral cephalograms, maxillary and mandibular anterior periapical radiographs, and bilateral posterior bitewing radiographs were obtained. During the 4-year follow-up period, all linear cephalometric measurements were significantly greater in men than in women. The amount of increase in the anterior facial height between T1 and T2 was lower in women than in men (P = 0.029). The rate of uprighting of the upper incisors was lower in men than in women over time (P = 0.020). The apex of the nose moved inferiorly between T0 and T2 (P = 0.006). The average overall change in the alveolar bone height was 0.27 mm and the yearly change was 0.07 mm over the 4-year period (P< 0.001). Significant changes in the skeletal, dental, and soft tissue, as well as, natural changes in alveolar bone, occur in young adults over time. Clin. Anat. 29:1011-1017, 2016. © 2016 Wiley Periodicals, Inc.

Is There a Difference in Stability After Intraoral Vertical Ramus Osteotomy Between Vertically High-Angle and Normal-Angle Patients?

PURPOSE: Few studies have evaluated the relapse pattern of intraoral vertical ramus osteotomy (IVRO) for the correction of mandibular prognathism with a high angle. The aim of this study was to measure the association between vertical facial types (high and normal mandibular plane angle) and relapse after IVRO for the management of mandibular prognathism. MATERIALS AND METHODS: The retrospective cohort study sample (skeletal Class III patients) was divided into 2 groups according to the angle of the sella-nasion plane relative to the mandibular plane (SN-MP) at the initial examination. Lateral cephalograms were analyzed for the predictor (facial type) and outcome (cephalometric changes over time) variables before surgery, 7 days after surgery, and 12 months after surgery. The 2 groups were matched for sample size (n = 20 in each). Data were analyzed using repeated-measures analysis of variance with Bonferroni correction. RESULTS: The normal-angle group (group N, SN-MP from 27° to 37°) and high-angle group (group H, SN-MP >37°) were not significantly different in terms of gender and age at the initial examination. Seven days after surgery, the mandibles in group H moved 2.5 mm more superiorly than those in group N (P = .013); consequently, the amount of overbite correction in group H was approximately 2 mm greater than that in group N (P = .002). Nevertheless, 12 months after surgery, there was no statistically significant difference in relapse of the maxilla and mandible between the 2 groups. In the 2 groups, the mandible moved approximately 0.7 mm superiorly during retention. CONCLUSIONS: These findings suggest that IVRO is a clinically acceptable and stable treatment modality for mandibular prognathism with a high angle.

Five-year investigation of a large orthodontic patient population at a dental hospital in South Korea.

OBJECTIVE: The purpose of this study was to investigate the characteristics of orthodontic patients at Yonsei Dental Hospital from 2008 to 2012. METHODS: We evaluated Angle's classification from molar relationships, classification of skeletal malocclusion from the A point-nasion-B point angle, facial asymmetry, and temporomandibular joint disorders (TMDs) from the records of 7,476 patients who received an orthodontic diagnosis. The orthognathic surgery rate, extraction rate, and extraction sites were determined from the records of 4,861 treated patients. RESULTS: The patient number increased until 2010 and gradually decreased thereafter. Most patients were aged 19-39 years, with a gradual increase in patients aged ≥ 40 years. Angle's Class I, Class II divisions 1 and 2, and Class III malocclusions were observed in 27.7%, 25.6%, 10.6%, and 36.1% patients, respectively, with a gradual decrease in the frequency of Class I malocclusion. The proportion of patients with skeletal Class I, Class II, and Class III malocclusions was 34.3%, 34.3%, and 31.4%, respectively, while the prevalence of facial asymmetry and TMDs was 11.0% and 24.9%, respectively. The orthognathic surgery rate was 18.5%, with 70% surgical patients exhibiting skeletal Class III malocclusion. The overall extraction rate among nonsurgical patients was 35.4%, and the maxillary and mandibular first premolars were the most commonly extracted teeth. CONCLUSIONS: The most noticeable changes over time included a decrease in the patient number after 2010, an increase in the average patient age, and a decrease in the frequency of Angle's Class I malocclusion. Our results suggest that periodic characterization is necessary to meet the changing demands of orthodontic patients.

Stability of Pre-Orthodontic Orthognathic Surgery Using Intraoral Vertical Ramus Osteotomy Versus Conventional Treatment.

PURPOSE: Postoperative skeletal and dental changes were evaluated in patients with mandibular prognathism who underwent mandibular setback surgery using an intraoral vertical ramus osteotomy (IVRO) with and without presurgical orthodontic treatment. MATERIAL AND METHODS: This retrospective cohort study included consecutive patients with skeletal Class III malocclusions who underwent IVRO. Patients treated with pre-orthodontic orthognathic surgery (POGS) were compared with patients treated with conventional surgery (CS) with presurgical orthodontics (control) using lateral cephalograms (taken preoperatively, 7 days postoperatively, and 12 months postoperatively). Predictor (group and timing), outcome (cephalometric measurements over time), and other (ie, baseline characteristics) variables were evaluated to determine the differences in postoperative horizontal and vertical positional changes of the mandible, such as point B. Baseline demographics were similar between the groups (N = 37; CS group, n = 17; POGS group, n = 20). The data were analyzed with an independent t test, the Mann-Whitney U test, the Fisher exact t test, Pearson correlation analysis, and simple linear regression analysis. RESULTS: The mean setback of the mandible at point B was similar, but the mandible of the POGS group, particularly the distal segment, moved superiorly during the postoperative period in conjunction with the removal of premature occlusal contacts (P < .001). In the CS group, the mandible had significantly more backward movement 12 months after surgery compared with the POGS group (P < .01). In the POGS group, horizontal and vertical postsurgical changes were linearly correlated with the amount of setback and vertical movement of the mandible. CONCLUSIONS: Mandibular setback surgery using IVRO without presurgical orthodontics leads to considerably different postoperative skeletal and dental changes compared with conventional treatment, with more superior movement being observed at point B during the 1-year postoperative period.

Mandibular molar protraction as an alternative treatment for edentulous spaces: Focus on changes in root length and alveolar bone height.

BACKGROUND: The authors conducted a retrospective cohort study to investigate external apical root resorption (EARR) and alveolar bone loss (ABL) after protraction of the mandibular molars by using miniscrews. METHODS: The authors protracted 51 mandibular molars in 37 adults into an edentulous area by using sliding mechanics with a lever arm or a miniscrew-supported root spring. The authors measured root length and alveolar bone height on panoramic radiographs and corrected according to the crown length registration method. The authors measured the amounts of crown movement (CM) and root movement (RM) on the superimposed lateral cephalometric radiographs along the mandibular occlusal plane. The authors used a linear mixed model to determine the risk factors for EARR and ABL. RESULTS: All edentulous spaces closed successfully in an average of 31.7 months, and the average CM and RM were 4.97 and 8.64 millimeters, respectively, with an RM:CM ratio of 2.81. The root length decreased significantly by 0.80 mm (5.53%), but EARR of more than 2 mm occurred in only 4.0% of molars. The alveolar bone height was reduced significantly by 0.56 mm, but ABL of more than 2 mm occurred in only 2.0% of molars. Linear mixed model results revealed that EARR and ABL correlated only with RM and age, respectively. CONCLUSIONS: Protraction of the mandibular molars into an edentulous area by using miniscrews was effective and safe, especially in younger adults. PRACTICAL IMPLICATIONS: Protraction of the mandibular molars can be considered as an alternative treatment to conventional prosthetic treatment in the restoration of edentulous space, especially in young adults, if patients accept longer treatment duration.