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This study aimed to assess the difference in the mesiodistal (MD) and buccolingual (BL) dimensions of primary first molars between Taiwanese boys and girls using a three-dimensional (3D) scanner (Microscribe G2 digitizer), record the coordinates in the 3D systems of Graph-R Project and reconstruct 3D images for subsequent analysis. We also determined whether the differences in these parameters between primary first molars and stainless steel crowns (SSC, 3M ESPE, No. 2-7) could be used as a reference for selecting a suitably-sized SSC and performing adjustments during restoration. The results indicated a statistically significant difference in the mesiodistal distance of lower primary first molar crowns between boys (7.75 ± 0.38 mm) and girls (7.41 ± 0.41 mm) ( p < 0.05) but no differences in the mesiodistal distance of upper primary first molars between the two sexes. The mean mesiodistal distances of the upper and lower primary first molars of boys were close to SSC size 4 and 3, respectively, while those of girls were close to size 3 in both arches. Overall, the buccolingual distance between the first maxillary and mandibular molars of Taiwanese children was greater than the buccolingual distance between the 3M ESPE SSC. Reducing the buccolingual length of the abutment teeth might quickly help achieve a better fit, reduce chair time, and minimize patient discomfort. In addition, trimming the mesial and distal metal margins of SSCs might help reduce microleakage from the crown margins and improve its retention and survival rate. In conclusion, the 3D scanning and analysis method used in this study can serve as a reference for fabricating SSC to achieve better crown adaptation and improve dental procedures., Competing Interests: The authors declare no conflict of interest., (©2023 The Author(s). Published by MRE Press.)

This cross-sectional study investigated developmental changes of pharyngeal airway structures. The materials were comprised of 120 lateral cephalometric radiographs and were divided into three stages according to the dental age. Results indicated that the upper pharyngeal depth increased with age, whereas, the lower pharyngeal depth was established early in life. The pharynx increases its capacity predominantly by vertical expansion. The developmental changes in pharyngeal structures were signficantly greater in males than in females.

A retrospective study, using panoramic radiographs, was conducted on 152 Taiwanese (72 males and 80 females) to investigate mandibular third molar eruption and impaction. The following measurements were made: inclinations and mesiodistal crown widths of the mandibular molars, vertical and horizontal spaces between the distal surface of the second molar and the anterior surface of the ramus, lengths and widths of the mandibular ramus and body, the ramus inclination, the mandibular plane angle, and the mandibular gonial angle. Differences between non-impaction and impaction groups were studied, and the variables were analyzed with multivariate discriminatory analysis. Significant differences between the two groups were found; variables describing spaces between the anterior of the ramus and the distal of the mandibular second molar and tooth size appeared to be the primary contributors to the differences observed.

Six hundred seventy-six Taiwanese children with deciduous dentition were sampled for maximum bite force and related dental status. Sixty-seven percent of children had at least one decayed tooth. The mean number of decayed teeth of all children was 2.97+/-3.58, and the mean plaque index of the right maxillary central incisor was 2.00+/-0.75. Twenty-seven percent of children had occlusal anomalies. Boys had a statistically significantly larger maximum bite force than did girls. Children with normal occlusion had statistically significantly larger maximum bite forces than did children with malocclusion. A statistically positive correlation was found between the number of decayed teeth and the plaque index. However, a statistically negative correlation was found between the number of decayed teeth and the maximum bite force and between the plaque index and the maximum bite force.

For this study, the general and dental health status of 463 Taiwanese children aged 9 to 12 years was evaluated. There were statistically significant increases in all measurements from Hellman's dental developmental stages IIIA to IVA except for the maximum mandibular protrusive, right lateral, and left lateral movements. Maximum bite forces had diminished in stage IIIB. Boys had larger maximum bite forces and hand-grip forces than did girls after stage IIIC. The proportion of subjects with TMD signs or symptoms increased to 60% by stage IVA.

The purpose of this study was to investigate the position of the mandibular foramen from deciduous (Hellman's stage IIA) to early permanent dentition (Hellman's stage IVA). Panoramic radiographs of 311 Taiwanese children were used. The results revealed that the distances between the mandibular foramen and ramus anterior plane were greater than those between the mandibular foramen and ramus posterior plane through all stages. The mean difference between them was the smallest (0.25 mm) in stage IIA and the greatest (1.18 mm) in stage IIIC. The distance from the mandibular foramen to the alveolar crest plane showed a little change from stage IIA (3.99 mm) to IVA (5.26 mm). The gonial angle had a negative correlation with the distances between the mandibular foramen and each mandibular border. Evaluation of the mandibular foramen from the oral aspect can be influenced by the degree of mouth opening.

This cross-sectional study investigated mandibular developmental changes in untreated normal Taiwanese from the deciduous to permanent dentition. Differences in the mean values for ramus height and body length between males and females were statistically significant after eruption of the permanent second molars. SNB angles significantly increased and gonial and L1-MP angles significantly decreased from deciduous to permanent dentition in both sexes. The SN-MP angle in females significantly decreased and ramus inclination in males significantly increased from the early mixed to permanent dentition.

This study identifies arch symmetry and describes arch form variations in normal primary maxillary dental casts. Sixty-two percent of casts had asymmetrical arches, and 38% had symmetrical arches. Six types of arch form were identified according to the ratio of arch width to length. There were more long types than short types. The rounded and short types tended to have a more-symmetrical arch than did the long type.

The purpose of this study was to investigate the developmental changes of the hyoid bone position in children from deciduous dentition to early permanent dentition. There was no sexual dimorphism in hyoid bone positions. The growth of the structures around the hyoid bone began to decline from late mixed dentition stage. During growth, Go-H was almost equal to C3-H and the hyoid bone was located near and above the line that connected C3 and Me.

The children with bimaxillary dentoalveolar protrusion in early mixed dentition were compared with the normal occlusion children. The bimaxillary dentoalveolar protrusion children had significant smaller inter-incisal angle and greater convexity, A-B plane, and ANB angles than the normal children. Maxillary and mandibular growths of the bimaxillary dentoalveolar protrusion girls were greater than those of normal girls. The direction of the mandibular growth of the bimaxillary dentoalveolar protrusion boys showed a tendency of downward and backward.

The outlines of mandibular rami, condyles, coronoid process, and corpus in panoramic radiographs of normal children from deciduous to early permanent dentition were traced and digitized. Nine linear and four angular measurements were measured. During the observation period, the lengths for all the linear measurements increased, however, the angles for all the angular measurements decreased. The shape of condyle and gonion significantly correlated with the growth of ramus and corpus.

The morphology of the deciduous teeth was investigated. The mean mesiodistal crown dimensions of the deciduous canine, first and second molars and the mean buccolingual crown dimensions of the deciduous second molars in both dental arches of boys were significantly larger than that of girls. The upper deciduous first molar of girls was slender buccolingually and the lower deciduous second molar of boys was slender mesiodistally.

This study investigated the developmental changes of mandibular permanent canines and premolars in early mixed dentition using panoramic radiographs. Positions of cusps and root apices of the teeth relative to the inferior border of mandible were evaluated. The developmental stages of the teeth were divided into three stages. There were few changes in the inclination of the three teeth. The permanent canine began to erupt before stage 2 and the second premolar began to erupt after stage 2. The distance between the inferior border of the mandible and apices of the three teeth was almost fixed in early mixed dentition.

Changes in position and mesiodistal angulations of maxillary and mandibular first permanent molars from early mixed dentition to early permanent dentition were measured on panoramic radiographs and compared with the values measured on lateral cephalometric radiographs. It was found that the maxillary and mandibular first permanent molars were uprighted gradually, drifted mesially and vertically, and that the changes in mesiodistal angulations were clearly on the panoramic radiographs in comparison with the cephalometric radiographs.

The purpose of this study was to investigate normal eruptive pattern of upper permanent canine. One hundred and fifty-one panoramic radiographs were used. Inclination of upper canine and lateral incisor, length and horizontal and vertical positions of cusp and root apex of the canine were evaluated. The canine erupted with increasing distal inclination and with no significant changes of the lateral incisor. Developmental changes of the canines relative to palatal plane and midline were shown by figures.

The purpose of this study was to investigate the facial morphologic characteristics in children with long and short faces. Lateral cephalometric radiographs of 46 children with long faces and 42 children with short faces were used. Both boys and girls with long faces exhibited upright incisors, excessive upper dentoalveolar development, shorter posterior face height, shorter ramus height and mandibular body, greater gonial angle and backward rotation of mandible when compared with those with short faces.

A case report of a 7-year-old boy who had Class III skeletal pattern is presented. The maxilla was deficient in anteroposterior and transverse dimensions, causing a slightly concave profile, a crossbite relationship of most of the anterior and posterior teeth, and upper anterior crowding. The rapid palatal expansion therapy effectively uprighted the posterior segments and developed the arches. Alignment, leveling and development of a good functional occlusion was accomplished with the .022" x .028" standard edgewise appliance.