The effects of pterygomaxillary disjunction in surgically assisted rapid maxillary expansion: A systematic review and meta-analysis.

OBJECTIVE: This study aims to assess the expansive effects of pterygomaxillary disjunction (PMD) in surgically assisted rapid maxillary expansion (SARME) surgery using a meta-analysis approach. MATERIALS AND METHODS: The study conducted a comprehensive literature search across five databases: PubMed, Scopus, Medline, Embase, and Cochrane, adhering to the PRISMA 2020 guidelines. Dental alterations were assessed using either cone-beam computed tomography (CBCT) or dental casts, while skeletal changes were exclusively measured from CBCT scans. We analysed the dentoskeletal changes between PMD +/- groups and conducted a within-group comparison. The primary focus of the results was on the mean differences observed in pre- and post-operative measurements. RESULTS: Dental expansion was larger in the PMD+ group but not statistically significant. Skeletal expansion showed a significantly larger expansion in the posterior region in the PMD+ group (P = .033). Without PMD, anterior palatal expansion was significantly larger (P = .03), and the buccal tipping of posterior teeth was also significantly larger (P = .011) to achieve acceptable dental expansion outcomes. CONCLUSIONS: Both PMD +/- groups of SARME surgery can achieve satisfactory dental expansion outcomes. However, bone expansion and tooth inclination are also important factors that influence orthodontic treatment and post-expansion stability. By reducing the bony resistance with PMD, larger posterior palatal expansion and more parallel bony expansion are observed. In contrast, without PMD, there is smaller palatal expansion and greater tooth inclination in the posterior region. This could potentially lead to compromised periodontal conditions following expansion.

Can different osteotomies have an influence on surgically assisted rapid maxillary expansion? A systematic review.

The purpose of this study was to systematically review the randomized and non-randomized clinical trials (RCT; nRCT) concerning the different available osteotomies for surgically assisted rapid maxillary expansion (SARME): pterygomaxillary disjunction (SARME + PD vs SARME-PD) and segmental Le Fort I osteotomy (2-piece vs 3-piece). Outcomes focused on skeletal, dental, upper airway changes, complications, and relapse. Two authors investigated five databases (PubMed, Cochrane Library, Google Scholar, Scopus, Web of Science) until August 2023. The Cochrane Collaboration Tool and the Newcastle-Ottawa scale were used for the quality assessment of the included RCTs and nRCTs, respectively. A total of 554 articles were retrieved and after duplicates removing and full-text reading, 40 studies were included. Two RCTs showed a low risk of bias, one an unclear risk and one a high risk. Among the non-RCTs, 15 studies showed a good quality, while 21 exhibited a fair quality score. SARME + PD resulted in more homogeneous posterior bone expansion, with minimal dental effects. No difference between 2-piece and 3-piece in asymmetric expansion was observed, although 3SO showed 1-2 mm of more transverse increase. The oropharynx minimum cross-sectional area, the nasopharynx and the oropharynx volume were greater in SARME + PD. Both dental and bone relapse can occur but no differences between the groups were observed. All osteotomies guaranteed a correction of transverse maxillary deficiency. Lower side effects were described in SARME + PD. Two-piece and 3-piece segmental Le Fort I osteotomies did not show any differences in the symmetry and amount of expansion.

Effects of different distractor positions on the formation of expansion, stress and displacement patterns in surgically assisted rapid maxillary expansion without pterygomaxillary disjunction: a finite element analysis study.

Skeletal orthopedic expansion of maxilla is accepted as a reliable method for the treatment of transverse maxillar deficiency in growing patients. The aim of the study was to evaluate the effects of different palatal distractor positions on the expansion, stress and displacement patterns of the structures of craniofacial complex in surgical assisted rapid maxillary expansion without pterygomaxillary disjunction (PTMD) with the help of finite element analysis(FEA). Four facial skeleton models with different distractor positions (first premolar, second premolar, first molar, second molar regions) were created. In all finite element models median and lateral osteotomies were performed, without PTMD. Stress distribution was evaluated after 5 mm activation of the transpalatal distraction in all models using the nonlinear solution method in FEA. Unilateral displacement(mm) and stress distribution(MPa) were measured in three directions (x, y, and z axes) of craniofacial and maxillofacial structures in the symmetrical finite element models. In all models, the unilateral transverse displacements of the anterior teeth were greater than those of the posterior teeth, and the greatest displacement was at the central incisor level. The greatest displacement values at the central incisor level, at the anterior nasal spine(ANS) and at the posterior nasal spine(PNS) levels was measured in Model-IV, III, II and I, respectively. Mean elemental stress(von Mises stress) in the medial pterygoid plate, screw and lateral pterygoid plate regions from highest to lowest was measured in Model-IV, III, II and I, respectively. The maxilla performed outward rotation and tipping movement in all models during the expansion period. Among the distractor positions, the second molar region was found to be the most advantageous one in terms of expansion pattern. Considering the patient's anatomy and clinical conditions, placing the palatal distractor as posteriorly as possible will result in more effective maxillary expansion.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-Tipping or Translation in Posterior Crossbite Correction?

The aim of this study was to investigate buccolingual tooth movements (tipping/translation) in surgical and nonsurgical posterior crossbite correction. A total of 43 patients (f/m 19/24; mean age 27.6 ± 9.5 years) treated with surgically assisted rapid palatal expansion (SARPE) and 38 patients (f/m 25/13; mean age 30.4 ± 12.9 years) treated with dentoalveolar compensation using completely customized lingual appliances (DC-CCLA) were retrospectively included. Inclination was measured on digital models at canines (C), second premolars (P2), first molars (M1), and second molars (M2) before (T0) and after (T1) crossbite correction. There was no statistically significant difference (p > 0.05) in absolute buccolingual inclination change between both groups, except for the upper C (p < 0.05), which were more tipped in the surgical group. Translation, i.e., bodily tooth movements that cannot be explained by pure uncontrolled tipping, could be observed with SARPE in the maxilla and with DC-CCLA in both jaws. Dentoalveolar transversal compensation with completely customized lingual appliances does not cause greater buccolingual tipping compared to SARPE.

Maxillary Expansion and Its Effects on Circummaxillary Structures: A Review.

Transverse maxillary discrepancies are the most common. The narrowed upper arch is the most prevalent problem an orthodontist encounter while treating adolescent and adult patients. Maxillary expansion is a technique used to increase the upper arch's transverse dimension to apply forces to widen the upper arch. For young children, a narrow maxillary arch has to be corrected using orthopedic and orthodontic treatments. In an orthodontic treatment plan, it is crucial to update transverse maxillary defeat. There are various clinical manifestations associated with a transverse maxillary deficiency which include a narrow palate, crossbite mainly seen in posteriors (unilateral or bilateral), severe crowding in anterior teeth, and cone-shaped hypertrophy can be seen. Some frequently used therapies for constricted upper arch include slow maxillary expansion, rapid maxillary expansion, and surgically assisted rapid maxillary expansion. Slow maxillary expansion requires light and constant force, whereas rapid maxillary expansion needs heavy pressure for activation. The surgical-assisted rapid maxillary expansion has gradually become popular to correct transverse maxillary hypoplasia. The maxillary expansion has various consequences on the nasomaxillary complex. There are multiple effects of maxillary expansion on the nasomaxillary complex. Mainly, the effect is seen on the mid-palatine suture along with the palate, maxilla, mandible, temporomandibular joint, soft tissue, and anterior and posterior upper teeth. It also affects functions like speech and hearing. Information on maxillary expansion is provided in depth in the following review article, along with its various effects on the surrounding structure.

Patient-specific pre-operative simulation of the surgically assisted rapid maxillary expansion using finite element method and Latin hypercube sampling: workflow and first clinical results.

Asymmetric distraction with different expansions of left and right maxillary parts is a serious complication of surgically assisted rapid maxillary expansion. An individual, highly standardized surgical intervention based on three-dimensional finite element analysis (FEA) is a new method to improve the quality of therapy. We describe a fundamental simulation-based workflow for preoperative evaluation of the osteotomies in a pilot study to achieve symmetry. A CT scan of the skull was used for analysis. Many feasible osteotomy configurations were generated and optimized using Latin hypercube sampling method and FEA choosing an individual osteotomy and maxillary movement. We successfully applied this workflow to 14 patients with symmetrical distraction.

Orthodontic and Orthognathic Treatment Combined withSurgically Assisted Rapid Maxillary Expansion in an Adult Patient with a Hyperdivergent Skeletal Pattern.

In this case study, we report the successful treatment of a 35-year-old woman with a hyperdivergent skeletal pattern, open bite and severe transverse deficiency, exhibiting a skeletal Class III malocclusion. The treatment plan included 3D correction of these issues with surgically assisted rapid maxillary expansion (SARME) to solve the transverse deficiency, presurgical orthodontic treatment including aligning and levelling of the teeth in both arches, LeFort I osteotomy and bilateral sagittal split ramus osteotomy, and postsurgical correction of malocclusion. Orthodontic treatment was performed with labial brackets, and the patient achieved satisfactory occlusion and a significantly improved facial profile. Retention at the 1-year follow-up showed stable occlusion and arch forms with a harmonious facial profile.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-The Amount of Posterior Crossbite Correction.

The aim of this study was to compare the crossbite correction of a group (n = 43; f/m 19/24; mean age 27.6 ± 9.5 years) with surgically assisted rapid palatal expansion (SARPE) versus a non-surgical transversal dentoalveolar compensation (DC) group (n = 38; f/m 25/13; mean age 30.4 ± 12.9 years) with completely customized lingual appliances (CCLA). Arch width was measured on digital models at the canines (C), second premolars (P2), first molars (M1) and second molars (M2). Measurements were obtained before treatment (T0) and at the end of lingual treatment (T1) or after orthodontic alignment prior to a second surgical intervention for three-dimensional bite correction. There was no statistically significant difference (p > 0.05) in the amount of total crossbite correction between the SARPE and DC-CCLA group at C, P2, M1 and M2. Maxillary expansion was greater in the SARPE group and mandibular compression was greater in the DC-CCLA group. Crossbite correction in the DC-CCLA group was mainly a combination of maxillary expansion and mandibular compression. Dentoalveolar compensation with CCLAs as a combination of maxillary expansion and mandibular compression seems to be a clinically effective procedure to correct a transverse maxillo-mandibular discrepancy without the need for surgical assistance.

Evaluation of symmetry behavior of surgically assisted rapid maxillary expansion with simulation-driven targeted bone weakening.

OBJECTIVES: Surgically assisted rapid maxillary expansion (SARME) is a treatment modality to overcome maxillary constrictions. During the procedure of transverse expansion, unwanted asymmetries can occur. This retrospective study investigates the transverse expansion behavior of the maxilla utilizing a simulation-driven SARME with targeted bone weakening. MATERIALS AND METHODS: Cone beam computer tomographies of 21 patients before (T1) and 4 months after treatment (T2) with simulation-driven SARME combined with a transpalatal distractor (TPD) and targeted bone weakening were superimposed. The movements of the left, right, and frontal segments were evaluated at the modified WALA ridge, mid root level, and at the root tip of all upper teeth. Linear and angular measurements were performed to detect dentoalveolar changes. RESULTS: Dentoalveolar changes were unavoidable, and buccal tipping of the premolars (6.1° ± 5.0°) was significant (p < 0.05). Transverse expansion in premolar region was higher (6.13 ± 4.63mm) than that in the molar region (4.20 ± 4.64mm). Expansion of left and right segments did not differ significantly (p > 0.05). CONCLUSION: Simulation-driven SARME with targeted bone weakening is effective to achieve symmetrical expansion in the transverse plane. CLINICAL RELEVANCE: Simulation-driven targeted bone weakening is a novel method for SARME to achieve symmetric expansion. Dental side effects cannot be prohibited.

Displacement and stress distribution of the maxilla under different surgical conditions in three typical models with bone-borne distraction: a three-dimensional finite element analysis.

OBJECTIVE: The present study compared the skeletal effects of surgically assisted rapid maxillary expansion (SARME) with different surgeries in three representative finite element (FE) models. STUDY DESIGN: According to the ossification level of midpalatal suture, three FE models, with different elasticity moduli of sutures (E = 1 MPa, 500 MPa, and 13,700 MPa) were constructed, to represent three age groups of patients. Within each model, four groups were set up according to different surgeries: group I (control group without surgery), II (paramedian osteotomy), III (pterygomaxillary separation), and IV (paramedian osteotomy and pterygomaxillary separation). An expansion force of 100 N and 1 mm displacement were applied via a bone-borne distraction to simulate the expansion process. RESULTS: By analyzing these models, the maximum displacement of maxilla was observed in group IV, with E = 1 MPa model exhibiting the most displacement (28.5â€¯× 10-6 mm), followed by group II (21.4â€¯× 10-6 mm). Group IV showed a unique backward-downward rotation with minimum stress distributions in three models (9 MPa, 131 MPa, and 140 MPa, respectively), and group II exhibited comparable low stress distributions (12 MPa, 151 MPa, and 230 MPa, respectively). Lowest stress was found in E = 1 MPa model, compared with the other two models. CONCLUSION: There is no need to perform surgeries when the midpalatal suture is open, and surgery guidelines are the same for partial and complete fusion sutures. Furthermore, exclusive use of partial paramedian osteotomy is sufficient enough to reduce stress and expand the posterior part of maxilla, and it is less invasive.

Effects of surgically assisted rapid maxillary expansion on the modification of the pharynx and hard palate and on obstructive sleep apnea, and their correlations.

PURPOSE: To investigate the changes induced by surgically assisted rapid maxillary expansion (SARME) on palate and pharynx morphology as well as the correlation of these changes with the improvement of obstructive sleep apnea (OSA). MATERIALS AND METHODS: The study was conducted in 16 patients, seven women and nine men, aged on average 40.23 ± 10.23 years, all of them with OSA confirmed by polysomnography (PSG) and with posterior crossbite. All participants underwent computed tomography (CT) and PSG before and after SARME. The CT scans were used to determine the dimensions of the palate and pharynx before and after surgery. Data were analyzed statistically by the paired t-test, Wilcoxon test and Pearson correlation, with the level of significance set at P < 0.05. RESULTS: A 56.24% reduction in apnea and hypopnea index was detected (from 33.23 ± 39.54 to 14.54 ± 19.48: P = 0.001). The total airway area increased on average by 23.99% (P = 0.016), although in a more expressive manner in its lower half (28.63%, P = 0.008). A 24% transverse bone increase was observed in the palate in the region of the first premolars and an 18% increase in the region of the first molars (from 2.42 ± 0.31 to 2.99 ± 0.26. P < 0.001, and from 3.11 ± 0.32 to 3.70 ± 0.41, P < 0.001, respectively), and a mean 15% reduction of its depth (from 1.07 ± 0.33 to 0.89 ± 0.18, P = 0.014). A moderate correlation was detected between palate depth and width and OSA severity, as well as a correlation of the reduction of palate depth and its transverse increase with the improvement of OSA, especially among patients with severe OSA. CONCLUSION: It appears that narrowing of the palate, especially in the premolar region, and its greater depth may be related to the severity of OSA. SARME promotes transverse maxillary widening and lowering of palate depth, thus reducing OSA among adults and expanding the airway, especially in its lower half.

Satisfactory outcomes after orthognathic surgery with surgically assisted rapid maxillary expansion using a hybrid device.

The self-reported functional outcomes, clinical findings, and results of dental cast analysis before and after orthognathic surgery with surgically assisted rapid maxillary expansion (SARME) using a hybrid rapid maxillary expander (RME) were evaluated. Data were collected from 43 patients who underwent orthognathic surgery with SARME using a hybrid RME between 2001 and 2013. The patients were recruited during a follow-up clinical examination and were required to complete a questionnaire about their opinions and self-reported functional outcomes. Dental casts were used to analyze posttreatment palatal expansion. The mean follow-up time was 68 months (range: 25-135 months). The most common indication for SARME was the presence of a crossbite. Of the 30 patients who underwent a follow-up clinical examination (69.8% answer rate), 4 (13.3%) had symptoms of temporomandibular disorder (TMD), 1 (3.3%) experienced myalgia, and 3 (10.0%) experienced arthralgia on clinical palpation. Cast analysis revealed significant palatal expansion. The intercanine distance, intermolar distance, and palatal height were increased by 3, 5, and 2 mm, respectively. Overall, the patients were satisfied with the preoperative information, improved functions, and aesthetic results. The prevalence of TMD symptoms and other side effects following orthognathic surgery with SARME using a hybrid RME was low, and significant palatal expansions were achieved.

Estudo clínico comparando duas técnicas de expansão ortocirúrgica da maxila: avaliação clínica e tomográfica / Clinical study comparing two techniques of surgically assisted rapid maxillary expansion: clinical and tomographic evaluation

O objetivo deste estudo foi comparar duas técnicas de expansão ortocirúrgica da maxila, a osteotomia convencional em 2 segmentos, entre os incisivos centrais superiores, versus a osteotomia em 3 segmentos entre os incisivos laterais e os caninos superiores bilateralmente. Um estudo prospectivo foi realizado com 19 pacientes. Foram divididos em dois grupos: osteotomia convencional em 2 segmentos (dez pacientes) e osteotomia em 3 segmentos (nove pacientes). Na metodologia do presente trabalho foram analizadas medidas dentárias e esqueléticas das imagens de tomografia computadorizada de feixe cônico, pré e pós-operatória. Foi realizada a sondagem periodontal pré e pós-operatória. A percepção estética dos pacientes foi avaliada em uma escala analógica visual colorida. Além disso o tempo decorrido durante a cirurgia foi medido com um cronômetro regular. A homocedasticidade foi confirmada pelo teste de Levene e o teste t das amostras independentes foi utilizado para comparar as médias. No presente estudo a expansão ortocirúrgica da maxila em três segmentos resultou em uma maior expansão transversa, menor inclinação dos dentes molares e menor comprometimento estético. A cirurgia levou mais tempo do que a expansão convencional em 2 segmentos, provavelmente devido à etapas extras e à curva de aprendizado do cirurgião (AU)

The purpose of this study was to compare the two surgically assisted rapid maxillary expansion techniques, the conventional 2-segment osteotomy between maxillary central incisors versus the 3-segment osteotomy between maxillary lateral incisors and canines bilaterally. A prospective study was conducted with 19 patients. they were divided into two groups: conventional 2-segment osteotomy (ten patients) and 3-segment osteotomy (nine patients). Dental and skeletal measurements of the preoperative and postoperative cone beam computed tomography images were analyzed in the present study. Pre and post-operative periodontal probing was performed, patients` cosmetic perception was evaluated in a colored visual analogue scale, and time elapsed during surgery was measured with a regular chronometer. Homoscedaticity was confirmed by the Levene`s test, and independent samples t-test was utilized to compare means. Three segment surgically assisted rapid maxillary expansion in the current study resulted in greater transverse expansion, less molar inclination and less aesthetic compromise. Surgery took longer than conventional 2 segment SARME probably due to extra steps and surgeon's learning curve (AU)

Nasal soft- and hard-tissue changes following tooth-borne and hybrid surgically assisted rapid maxillary expansion: A randomized clinical cone-beam computed tomography study.

PURPOSE: The aim of this study was to assess the effects of tooth/bone-borne (hybrid) and tooth-borne (TB) surgically assisted rapid maxillary expansion (SARME) on the width of the nasal soft and hard tissue. PATIENTS AND METHODS: Twenty skeletally mature patients (nine males and 11 females; mean age 19.4 years) with transverse maxillary hypoplasia were randomly assigned to hybrid or TB devices. The patients had undergone SARME operations, performed by the same surgical team using the same procedure (Le Fort I osteotomy with pterygomaxillary dysjunction, midline osteotomy, and no down-fracture). Nasal soft- and hard-tissue changes were analyzed using CBCT preoperatively (T0), at the end of the active expansion phase (T1), and after 6 months of retention (T2). The study was approved by the relevant ethics committee. RESULTS: The skeletal and soft-tissue nasal parameters increased significantly in the T0-T1 and T0-T2 periods in both groups (P < 0.05). No statistically significant differences between the groups were observed. The mean piriform aperture width increased from 1.26 mm in T0-T1 to 0.97 mm in T1-T2 and 2.17 mm in T0-T2 (P < 0.008). In the soft tissue, the alar base width increased to 2.78 mm and the alar width to 2.95 mm in T0-T2 (P = 0.001). There was a positive correlation (63.6%) between the changes in skeletal and soft-tissue values. CONCLUSION: The hybrid and TB devices led to similarly significant widening effects in nasal soft and hard tissues in both the short term and 6 months after SARME.

Does surgically assisted rapid maxillary expansion associated with pterygomaxillary disjunction result in changes in mandibular position? A PROSPERO-compliant systematic review of the literature.

PURPOSE: This study aimed to assess the effect of surgically assisted rapid maxillary expansion (SARME) associated with pterygomaxillary disjunction (PD) on mandibular positioning. MATERIALS AND METHODS: A two-phase systematic review registered with the PROSPERO database was performed. Search strategies were developed for specific databases (PubMed, Scopus, Web of Science, COCHRANE, LILACS, and DOSS), including the gray literature (Open Gray, Google Scholar, and ProQuest). The methodological and evidential quality of the included studies were assessed. RESULTS: Among 680 studies, four were selected for inclusion. In general, a low risk of bias was observed. The studies included a total of 142 adults, and used imaging to perform linear measurements (preoperatively and postoperatively). The main outcomes were maxillomandibular transverse index (difference between effective mandibular width - distance between the left and right antagonist points - and maxillary width), sagittal (forward and backward) and vertical (impaction and extrusion) changes, dental show, chin projection, and altered mandibular position. CONCLUSION: Although the study demonstrated some mandibular position changes after SARME associated with PD, there is insufficient current evidence to support this result because of the potential study limitations related to the number of investigations chosen for inclusion. Further research is required to validate this finding.

Nasal soft tissue changes after two different approaches for surgically assisted rapid maxillary expansion.

The aim of the study was to evaluate the nasal soft tissue changes in patients who underwent surgically assisted rapid maxillary expansion (SARME) using two different surgical approaches. Thirty-two patients were included in the study, and divided into two groups according to the type of surgical approach: in group A (n=17), SARME performed with standard Le Fort I circumvestibular approach with alar base cinch and anterior nasal spine (ANS) exposure; and in group B (n=15) operations were performed with the same standard Le Fort I circumvestibular approach with only alar base cinch. Measurements of height and width of the philtrum, nasal and subnasal width, and columella width were taken from three-dimensional facial images obtained before surgery (T1), after the distraction phase (T2) and 6 months postoperatively (T3). The mean maxillary expansion was 7.3±0.7mm for group A and 7.5±1.5mm for group B, without any significant difference between groups (P=0.59). Both groups presented an increase in all vaules in T2 and T3. The approach used in group A resulted in smaller changes in the columella width. The results of the present study show that there is no need for intraoperative releasing of the soft tissues around the anterior nasal spine during SARME if columella width is sufficient. However, further randomized studies based on large patient groups are needed before final conclusions on this topic can be reached.

Surgically assisted rapid maxillary expansion with bone-borne versus tooth-borne distraction appliances-a systematic review.

The objective was to test the hypothesis of no difference in skeletal and dental arch expansion and relapse after surgically assisted rapid maxillary expansion with a bone-borne compared with a tooth-borne appliance. The PubMed, Embase (Ovid), Cochrane Library, and Google Scholar databases were searched in combination with a hand-search of relevant journals up until December 2017. No language restriction was applied. Two short-term randomized controlled trials with a low risk of bias fulfilled the inclusion criteria. No meta-analysis could be performed due to considerable heterogeneity. There were no statistically significant differences in the skeletal and dental arch expansion and relapse. Dental arch expansion was significantly greater than skeletal expansion with both treatment modalities. However, dissimilar evaluation methods, different outcome measures, unknown vertical level of force application with the bone-borne devices, and various methodological confounding factors posed serious restrictions to reviewing the literature in a quantitative systematic manner. Hence, conclusions drawn from the results of this systematic review should be interpreted with caution. Further well-designed long-term randomized clinical trials including a standardized protocol and three-dimensional analysis of the level of force application and morphological outcome are therefore needed before one treatment modality can be considered superior to the other.

Skeletal Age-related Changes of Midpalatal Suture Densities in Skeletal Maxillary Constriction Patients: CBCT Study.

AIM: To determine if density measurements of the midpalatal suture and cervical vertebral maturation index (CVMI) are related, and to investigate if CVMI could help in predicting of the developmental status of the midpalatal suture. MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) images of 95 skeletal maxillary constriction patients (aged 8 to 18 years) were examined. The maturational stages of the cervical vertebrae were visually defined, and midpalatal suture density in the anterior region, the middle region, and the posterior region were measured. One-way ANOVA and Fisher's least significant difference (LSD) post-hoc test were used for statistical assessment. RESULTS: Significant differences were found in MPDS: in anterior region between (c1,c2,c3,c4) and (c5,c6) stages, in middle region between (c1,c2,c3) and (c5,c6) stages, and in posterior region between (c1,c2,c3) and (c4,c5,c6) stages. CONCLUSION: Midpalatal suture densities in all regions increase with skeletal maturation advancement.The significant increase after puberty may have the key role in decreasing the skeletal effects of RME after that age. Clinical significances: It is important to assess the midpalatal suture density to choose between rapid maxillary expansion (RME) and surgically assisted rapid maxillary expansion (SARME). This study revealed a significant increase in the midpalatal suture density after puberty. Thus, it may better to perform RME before puberty.

Expansion patterns in surgically assisted rapid maxillary expansion : Transpalatal distractor versus hyrax appliance.

OBJECTIVES: The purpose of this work was to compare the patterns of expansion resulting from a tooth-borne hyrax appliance and a bone-borne transpalatal distractor in patients treated by surgically assisted rapid maxillary expansion (SARME). METHODS: A total of 28 patients with transverse maxillary hypoplasia were treated by SARME, using a hyrax appliance in 12 and a transpalatal distractor in 16 cases. Before and after palatal expansion, an impression of each maxilla was taken. Casts fabricated on this basis were digitized with a 3D scanner. Based on the resultant virtual models, both the amounts of expansion and the angles of crown tipping from the canines through the second molars were determined and the results of the two groups were compared. RESULTS: Almost all measurement sites revealed significant expansion of the dental arches over the course of SARME. The sites of maximum expansion were more anterior in the distractor group, while larger total amounts of expansion were seen in the hyrax group. Both appliances involved buccal tipping of almost all canines, premolars, and molars; these findings were more pronounced in the hyrax group. CONCLUSIONS: Either a transpalatal distractor or a hyrax appliance can be successfully used to expand a narrow maxilla by SARME. The two appliances, however, cause different amounts of dental arch expansion and buccal crown tipping. A hyrax appliance should be expected to result in a parallel expansion pattern with the largest increase in the premolar area. A transpalatal distractor is likely to cause more of a V-shaped pattern of expansion. Thus, in clinical practice, specific patterns of distraction can be selectively achieved by taking advantage of specific appliances and various options of positioning.