• Restorative Dentistry and Endodontics
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• v.47 no.2
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• pp.19.1-19.15
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• 2022

Objectives: The aim of this study was to evaluate and compare the apical constriction (AC) and apical canal morphology of maxillary first and second molars, using micro-computed tomography (micro-CT). Materials and Methods: The anatomical features of 313 root canals from 41 maxillary first molars and 57 maxillary second molars of patients with known age and sex were evaluated using micro-CT, with a resolution of 26.7 ㎛. The factors evaluated were the presence or absence of AC, the morphotypes, bucco-lingual dimension, mesio-distal dimension, and the profile (shape) of AC and the apical root canal. The apical root canal dimensions, location of the apical foramen (AF), AC to AF distance, and presence of accessory canals in the apical 5 mm were also assessed. Descriptive and analytical statistics were used for data evaluation. Results: AC was present in all 313 root canals. Patients' age and sex did not significantly impact either AC or the apical canal dimensions. The most common AC morphotype detected was the traditional (single) constriction (52%), followed by the parallel (29%) morphotype. The mean AC dimensions in maxillary first molars were not significantly different from those in maxillary second molars. Sixty percent of AF were located within 0.5 mm from the anatomic apex. Conclusions: The most common morphotype of AC detected was the traditional constriction. Neither patients' age nor sex had a significant impact on the dimensions of the AC or the apical root canal. The majority of AF (60%) were located within 0.5 mm from the anatomic apex.

• The korean journal of orthodontics
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• v.49 no.1
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• pp.49-58
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• 2019

Objective: The aim of this retrospective study was to evaluate and compare the changes in the pharyngeal airway (PA), maxillary sinus volume, and skeletal parameters after rapid maxillary expansion (RME) and alternate rapid maxillary expansion and constriction (Alt-RAMEC) followed by facemask (FM) therapy. Methods: The records of 40 patients with skeletal Class III malocclusion due to maxillary retrognathism were collected, and the patients were assigned into two groups. The first group comprised 8 male and 12 female patients (mean age, $10.0{\pm}1.1years$) treated using RME/FM for an average of 10 months. The second group comprised 10 male and 10 female patients (mean age, $9.64{\pm}1.3years$) treated using Alt-RAMEC/FM for an average of 12 months. Cone-beam computed tomography images acquired before (T0) and after treatment (T1) were evaluated. Results: Regarding the skeletal effects, significant differences between the groups were the increase in ANS-HRP (perpendicular distance of ANS to the horizontal reference plane, 0.99 mm, p <0.05) in the Alt-RAMEC/FM group and the decrease in PP-SN (palatal plane to Sella-Nasion plane, $0.93^{\circ}$, p < 0.05) in the RME/FM group. Maxillary sinus volumes increased significantly in both the groups, and the increase was statistically significantly higher in the Alt-RAMEC/FM group. Although no significant intergroup differences were observed in PA volumes, both lower ($1,011.19mm^3$) and total ($1,601.21mm^3$), PA volume increased significantly in the Alt-RAMEC/FM group. Conclusions: The different expansion devices and protocols used with FM therapy do not seem to affect the forward movement of the maxilla and PA volumes. In contrast, the increase in maxillary sinus volume was greater in the Alt-RAMEC/FM protocol.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.20.1-20.6
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• 2016

Background: Most of cleft lip and palate patients have the esthetic and functional problems of midfacial deficiencies due to innate developmental tendency and scar tissues from repeated operations. In these cases, maxillary protraction is required for the harmonious facial esthetics and functional occlusion. Case presentation: A 7-year old boy had been diagnosed as severe maxillary constriction due to unilateral complete cleft lip and palate. The author tried to correct the secondary deformity by early distraction osteogenesis with the aim of avoiding marked psychological impact from peers of elementary school. From 1999 to 2006, repeated treatments, which consisted of Le Fort I osteotomy and face mask distraction, and complementary maxillary protraction using miniplates were performed including orthodontics. But, final facial profile was not satisfactory, which needs compromising surgery. Conclusions: The result of this study suggests that if early distraction treatment is performed before facial skeletal growth is completed, an orthognathic surgery or additional distraction may be needed later. Maxillofacial plastic and reconstructive surgeons should notify this point when they plan early distraction treatment for cleft maxillary deformity.

• The korean journal of orthodontics
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• v.49 no.1
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• pp.59-69
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• 2019

In this report, we describe a case involving a 34-year-old woman who showed good treatment outcomes with long-term stability after multidisciplinary treatment for unilateral cleft lip and palate (CLP), maxillary hypoplasia, severe maxillary arch constriction, severe occlusal collapse, and gingival recession. A comprehensive treatment approach was developed with maximum consideration of strong scar constriction and gingival recession; it included minimum maxillary arch expansion, maxillary advancement by distraction osteogenesis using an internal distraction device, and mandibular setback using sagittal split ramus osteotomy. Her post-treatment records demonstrated a balanced facial profile and occlusion with improved facial symmetry. The patient's profile was dramatically improved, with reduced upper lip retrusion and lower lip protrusion as a result of the maxillary advancement and mandibular setback, respectively. Although gingival recession showed a slight increase, tooth mobility was within the normal physiological range. No tooth hyperesthesia was observed after treatment. There was negligible osseous relapse, and the occlusion remained stable after 5 years of post-treatment retention. Our findings suggest that such multidisciplinary approaches for the treatment of CLP with gingival recession and occlusal collapse help in improving occlusion and facial esthetics without the need for prostheses such as dental implants or bridges; in addition, the results show long-term post-treatment stability.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.1
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• pp.53-60
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• 2009

Maxillary deficiency, anterior cross bite, constriction of maxillary arch, malaligned teeth are frequently observed in patients with cleft lip and palate. Surgery and orthodontics, combined intervention are needed to correct maxillary deficiency. Distraction osteogenesis that currently used has many advantages like less relapse tendency, more advancement of maxilla, capable in growing patients. In case 1, 18 years old girl with BCLP had severe midfacial deficiency and multiple missing of teeth. LeFort I osteotomy, followed by maxillary distraction osteogenesis utilizing rigid external distraction device(RED) system, was performed. After a 6-day latency period, distraction proceeded at a rate of 1mm per day (at 1st week, 1.5mm/day). Total advancement was 19mm. The RED device left in place for the additional 4 weeks for consolidation. After the RED device was removed, face mask was applied with elastic traction for 5 weeks. After achieving acceptable facial appearance and occlusion, orthodontic appliance was removed. The results after 4 years follow-up was sustained pretty well without aggravation of velopharyngeal function. In case 2, 22 years old man with UCLP had severe midfacial deficiency and palatally erupted upper 2nd premolars due to arch length discrepancy, but the anterior segment of maxillary did not show constriction and crowding. patient had no arch width discrepancy, crowding was concentrated on premolar region. Segmental LeFort I osteotomy was performed. After a 6 - day latency period, using internal distraction device, distraction proceeded at a 0.5mm per day(at 1st week, 0.75 - 1 mm/day). Total advancement was 15mm. After internal distraction device was removed, face mask was applied with elastic traction for 4 weeks. After surgical-orthodontic treatment, facial appearance and occlusion was improved pretty good, and after 46 months follow-up the result was retained well.

• The korean journal of orthodontics
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• v.53 no.3
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• pp.175-184
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• 2023

Objective: To evaluate and compare a series of volume changes in the nasal cavity (NC), nasopharynx, oropharynx, and maxillary sinuses (MS) in growing Class III patients after either rapid palatal expansion (RPE) or alternate rapid maxillary expansion and constriction (Alt-RAMEC) followed by facemask (FM) therapy, by using cone-beam computed tomography (CBCT). Methods: Forty growing Class III patients were retrospectively selected and divided into two matched groups: RPE/FM (14 females, 6 males; mean age, 9.66 ± 1.23 years) and Alt-RAMEC/FM groups (14 females, 6 males; mean age, 10.28 ± 1.45 years). The anteroposterior and vertical displacements of Point A, the volumes of the NC, nasopharyngeal, oropharyngeal, and MS were measured at different time points: pretreatment (T1), postexpansion (T2), and postprotraction (T3). Results: Both groups demonstrated significant maxilla advancement (by 1.3 mm) during expansion, with a statistically significant intergroup difference during protraction (RPE/FM, 1.1 mm; Alt-RAMEC/FM, 2.4 mm; p < 0.05) and throughout the treatment (RPE/FM, 2.4 mm; Alt-RAMEC/FM, 3.7 mm; p < 0.05). NC and nasopharyngeal airway volumes increased significantly in both groups after expansion, protraction, and treatment. The oropharyngeal and MS volumes increased in both groups after protraction and post-treatment. However, no volumetric differences were observed between the two groups. Conclusions: There was no significant difference in airway volume changes, including NC, nasopharyngeal, oropharyngeal airway, and MS, between RPE/FM and Alt-RAMEC/FM groups at different time points. Although there was significantly more forward movement after protraction in the Alt-RAMEC/FM group, the difference was deemed too small to be clinically relevant.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.657-670
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• 1991

It was said that early rapid palatal expansion was the treatment of choice in case of maxillary constriction with posterior crossbite. The author tried to assess dimensional changes of nasal and oral cavity before rapid palatal expansion and over 4 months of retention by use of three coronal tomograms through the incisal, molar, and maxillary tuberosity areas. The subjects of this study were consisted of 9 boys and 11 girls ranging from 11 to 13 years old. The results were as follows: 1. A mean change in maxillary first molar width was 3.68mm and a mean change in nasal cavity width was 2.26mm after 6.70mm expansion by Hyrax-type screw and over 4 months of retention tomographically in molar cut. 2. A change in nasal cavity width tomographically showed in order of molar cut, incisal cut, maxillary tuberosity cut respectively. 3. There was no correlation between changes in oral cavity width and nasal cavity width.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.190-197
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• 2015

Objective: The aim of the study was to analyze the prevalence and distribution of ectopic eruption of the permanent maxillary first molar (EEM) in individuals scheduled for orthodontic treatment and to investigate the association of EEM with dental characteristics, maxillary skeletal features, crowding, and other dental anomalies. Methods: A total of 1,317 individuals were included and randomly divided into two groups. The first 265 subjects were included as controls, while the remaining 1,052 subjects included the sample from which the final experimental EEM group was derived. The mesiodistal (M-D) crown width of the deciduous maxillary second molar and permanent maxillary first molar, maxillary arch length (A-PML), maxillomandibular transverse skeletal relationships (anterior and posterior transverse interarch discrepancies, ATID and PTID), maxillary and mandibular tooth crowding, and the presence of dental anomalies were recorded for each subject, and the statistical significance of differences in these parameters between the EEM and control groups was determined using independent sample t -tests. Chi-square tests were used to compare the prevalence of other dental anomalies between the two groups. Results: The prevalence of maxillary EEM was 2.5%. The M-D crown widths, ATID and PTID, and tooth crowding were significantly greater, while A-PML was significantly smaller, in the EEM group than in the control group. Only two subjects showed an association between EEM and maxillary lateral incisor anomalies, which included agenesis in one and microdontia in the other. Conclusions: EEM may be a risk factor for maxillary arch constriction and severe tooth crowding.

• The korean journal of orthodontics
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• v.53 no.1
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• pp.54-64
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• 2023

This case report describes skeletal anchorage-supported maxillary protraction performed with the Alternate Rapid Maxillary Expansion and Constriction (AltRAMEC) protocol over a treatment duration of 14 months in a 16-year-old female patient who was in the late growth-development period. Miniplates were applied to the patient's aperture piriformis area to apply force from the protraction appliance. After 9 weeks of following the Alt-RAMEC protocol, miniplates were used to transfer a unilateral 500-g protraction force to a Petit-type face mask. A significant improvement was observed in the soft tissue profile in measurements made both cephalometrically and in three dimensional photographs. Subsequently, the second phase of fixed orthodontic treatment was started and the treatment was completed with the retention phase. Following treatment completion, occlusion, smile esthetics, and soft tissue profile improved significantly in response to orthopedic and orthodontic treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.171-181
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• 2009

The objective of this study was to analyse stress distribution of maxillary complex by use of face mask. The construction of the three-dimensional FEM model was based on the computed tomography(CT) scans of 13.5 years-old male subject. The CT image were digitized and converted to the finite element model by using the mimics program, with PATRAN. An anteriorly directed force of 500g was applied at the first premolar 45 degrees downwards to the FH plane and at the first molar 20 degrees downwards to the FH plane. When 45 degrees force was applied at maxillary first premolar, there were observed expansion at molar part and constriction at premolar part. The largest displacement was 0.00011mm in the x-axis. In the y-axis, anterior displacement observed generally 0.00030mm at maximum. In the z-axis, maxillary complex was displaced 0.00036 mm forward and downward. When 20 degrees force was applied at maxilla first molar, there were observed expansion at lateral nasal wall and constriction at molar part. The largest displacement was 0.001mm in the X-axis. In the Y-axis, anterior displacement observed generally 0.004mm at maximum. In the Z-axis, ANS was displaced upward and pterygoid complex was displaced downward. The largest displacement was 0.002mm.