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Objectives: To assess the impact of including the palate and the number of images recorded during intraoral digital scanning procedure on the accuracy of complete arch scans., Methods: An experienced operator conducted 40 digital scans of a 3D printed maxillary model and divided them into two groups: 20 with inclusion of the palate (PAL) and 20 without (NPAL). Each set of scans was performed using an intraoral scanner (IOS) (Trios 5; 3Shape A/S; Copenhagen, Denmark). The resulting STL files were imported into the Geomagic Control X software (3D Systems, Rock Hill, SC, USA) for accuracy comparison. A reference STL file was created using a 3Shape E3 laboratory scanner (3Shape Scanlt Dental 2.2.1.0; Copenhagen, Denmark). The number of images captured was recorded during the scanning procedure., Results: In the case of the right side no statistically significant difference in trueness was detected (84 µm ± 45.6 for PAL and 80.4 ± 40.4 µm for NPAL). In the case of the left side no significant difference in trueness was observed (215.1 ± 70.2 µm for PAL and 233.9 ± 70.7 µm for NPAL). In the case of the arch distortion a statistically significant difference in trueness was seen between the two types of scans (135.3 ± 71.9 µm for PAL and 380.4 ± 255.1 µm for NPAL). The average number of images was 831.25, and 593.8 for PAL and NPAL, respectively., Conclusions: Scanning of the palatal area can significantly improve the accuracy of dental scans in cases of complete arches. In terms of the number of images, based on the current results, obvious conclusions could not be drawn, and further investigation is required., Clinical Significance: Scanning the palate may be beneficial for improving the accuracy of intraoral scans in dentate patients. Consequently, this should be linked to an appropriate scanning strategy that predicts palatal scanning., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Studies focusing on accuracy of intraoral digital models in the palatal region are scarce. The present study aimed to investigate the influence of different scanning sequences on palatal trueness and to assess deviation and distribution character of trueness in palate., Methods: Overall, 35 participants accepted three types of procedures to acquire upper digital models. Indirect models digitalised from plaster models were considered as the reference. Two direct digital models were acquired using TRIOS 3 POD intraoral scanners, namely Groups Tr1 and Tr2, wherein intraoral scanning differed in terms of palatal scanning sequences. Based on a modified dental-level superimposition method, 3D measurements of trueness in palate and palatal vault region (PVR) for palatal stable regional superimposition in Groups Tr1 and Tr2, respectively, were performed. Absolute deviations were measured for trueness, while signed deviations were analysed for shape distortion. Colour-coded maps were used for quantitative analysis of deviation distribution pattern. Paired t test was used to analyse differences in palatal trueness between different scanning sequences. One-way repeated-measures analysis of variance and Bonferroni test were used to compare trueness measurements among different superimposition methods. Intraclass correlation coefficient (ICC) was used to verify reproducibility of the proposed method., Results: Palatal trueness in Group Tr1 (118.59 ± 37.67 μm) was slightly less accurate than that (108.25 ± 33.83 μm) in Group Tr2 (p = 0.012 < 0.05). Trueness of PVR in Groups Tr1 (127.35 ± 54.11 μm) and Tr2 (118.17 ± 49.52 μm) did not differ significantly (p = 0.149). Moreover, no significant difference was noted in distortion of the palatal region and PVR in Groups Tr1 and Tr2 (p = 0.582 and 0.615, respectively). A similar pattern of palatal trueness was noted in a majority of participants (22/35). For 3D palatal trueness measurement, there were different applications for different superimposition methods. ICC for the proposed method was > 0.90., Conclusions: Scanning sequences can affect palatal trueness. Palatal scanning should be initiated at the palatal side of the posterior teeth where the initial scan begins. For 3D PVR superimposition, distal boundary of the selected region should be adjusted mesially whilst referring to intraoral digital models., Trial Registration: The trial has been registered (registration No: R000039467 , Trial ID: UMIN000034617, date of registration: 2018/10/24'retrospectively registered').

Aims: This was to compare sleepiness, occlusion, dental arch and palatal dimensions between children with attention deficit hyperactivity disorders (ADHD) and healthy children (control group)., Methods: 15 children with ADHD (10 boys, 5 girls, mean age 10.98 years) and 36 healthy age matched children (21 boys, 15 girls, mean age 10.60 years) were included. Intra-oral three-dimensional scans of the teeth and palate were performed to evaluate the occlusion, dental arch and palatal dimensions. Sleepiness was evaluated from the questionnaires. The differences between the two groups were analysed by Fisher's exact test and general linear models adjusted for age and gender., Results: The ADHD children had a significantly narrower dental arch at the gingival level of the canines (p < 0.05) and a tendency to increased prevalence of posterior cross-bite compared to the controls (13.3 vs. 0.0%, p = 0.086). The ADHD children snored significantly more (p < 0.05) and slept restlessly significantly more often (p < 0.0005) compared to the controls. The ADHD children had a tendency to sleep fewer hours during the night (p = 0.066) and felt inadequately rested in the morning (p = 0.051) compared to the controls., Conclusion: The results indicate that sleepiness and palatal width, especially the more anterior skeletal part of the palate, may be affected in children with ADHD. The results may prove valuable in the diagnosis and treatment planning of children with ADHD. Further studies are needed to investigate sleep and dental relations in children with ADHD.

Background/aims: Speech impairment during the initial phase of removable partial denture (RPD) treatment can prevent patient adaptation to RPDs. This study was undertaken to investigate the influence of oral morphology on speech production in subjects wearing RPDs with major connectors., Methods: Two types of connectors were fabricated for 17 subjects with normal dentitions: covering the middle palate (M-bar) and the anterior/posterior palate (AP-bar). Four target sounds ([∫i], [t∫i], [çi], and [ki]) were evaluated under 3 recording conditions: no connector, M-bar, and AP-bar. The mean appearance ratios of correct labels (MARCs) were calculated as parameters representing speech production accuracy with the speech evaluation system. Subgroup analysis was conducted based on palate height, dental arch width, and front space volume of the oral cavity., Results: Based on the multiple linear regression test, a significant association was found between the MARCs of [∫i] with M-bar and front space (p = 0.036). In the subgroup analysis, the AP-bar had a significant effect on the MARCs of [∫i] among subjects with high palate (p = 0.026), narrow arch (p = 0.004), and small front space (p = 0.014)., Conclusion: RPDs with major connectors could disturb speech production among patients with high palates, narrow arches, and small front spaces., (© 2018 S. Karger AG, Basel.)

The palate is considered typical of the structures in which schizophrenia-related minor physical anomalies may occur. In this study, we aimed to compare the dimensions and form of palate in patients with schizophrenia with nonpsychiatric controls in a blinded manner. Dental stone casts of 127 patients with schizophrenia and 127 controls were prepared from impressions of the maxillary dental arch. Palate dimensions were measured on the stone casts using a digital caliper and palatometer. Palate length did not differ significantly between the groups, but there was a significant difference in palate width and depth, which were significantly higher in the schizophrenia group. As a result of using multivariate analysis for assessing independent risk factors affecting patients with schizophrenia, furrowed palate shape, palate width, and ellipsoid maxillary dental arch shape were found to be significant. This study also revealed that patients with schizophrenia demonstrate certain gender-related predilections in the differences of palate parameters compared to same-sex controls. As the palate develops in conjunction with both the face and brain, our study findings can significantly contribute to the assumption that there might be structural abnormalities of the palate that could represent specific markers of embryological dysmorphogenesis underlying schizophrenia., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Intraoral digital impressions have been stated to meet the clinical requirements for some teeth-supported restorations, though fewer evidences were proposed for larger scanning range. The aim of this study was to compare the accuracy (trueness and precision) of intraoral digital impressions for whole upper jaws, including the full dentitions and palatal soft tissues, as well as to determine the effect of different palatal vault height or arch width on accuracy of intraoral digital impressions. Thirty-two volunteers were divided into three groups according to the palatal vault height or arch width. Each volunteer received three scans with TRIOS intraoral scanner and one conventional impression of whole upper jaw. Three-dimensional (3D) images digitized from conventional gypsum casts by a laboratory scanner were chose as the reference models. All datasets were imported to a specific software program for 3D analysis by "best fit alignment" and "3D compare" process. Color-coded deviation maps showed qualitative visualization of the deviations. For the digital impressions for palatal soft tissues, trueness was (130.54±33.95)μm and precision was (55.26±11.21)μm. For the digital impressions for upper full dentitions, trueness was (80.01±17.78)μm and precision was (59.52±11.29)μm. Larger deviations were found between intraoral digital impressions and conventional impressions in the areas of palatal soft tissues than that in the areas of full dentitions (p<0.001). Precision of digital impressions for palatal soft tissues was slightly better than that for full dentitions (p = 0.049). There was no significant effect of palatal vault height on accuracy of digital impressions for palatal soft tissues (p>0.05), but arch width was found to have a significant effect on precision of intraoral digital impressions for full dentitions (p = 0.016). A linear correlation was found between arch width and precision of digital impressions for whole upper jaws (r = 0.326, p = 0.034 for palatal soft tissues and r = 0.485, p = 0.002 for full dentitions). It was feasible to use the intraoral scanner to obtain digital impressions for whole upper jaws. Wider dental arch contributed to lower precision of an intraoral digital impression. It should be confirmed in further studies that whether accuracy of digital impressions for whole upper jaws is clinically acceptable.

Objective: The aim of the present study was to analyze the variations of maxillary arch size and of palatal morphology in subjects with prolonged mouth-breathing due to allergic rhinitis when compared with a control group with normal breathing pattern by using a three-dimensional analysis on digital casts., Methods: 26 Caucasian children (19 females and 7 males) with a mean age of 8.5 years (SD 1.6 years) were selected according to the following criteria: mouth-breathing pattern due to allergic rhinitis, early mixed dentition, skeletal Class I relationship and prepubertal stage of cervical vertebral maturation. The study group was compared with a control group of 17 nasal breathing subjects (9 females; 8 males, mean age 8.5 years SD 1.7 years). For each subject an initial dental cast was taken and the upper arch was scanned by using a tridimensional scanner. On each digital model linear measurements were performed to analyze maxillary arch dimensions and palatal morphology. Significant between-group differences were tested with the Student t-test (p<0.05)., Results: the transverse dimension of the upper arch was significantly smaller in subjects of the study group thus confirming the influence of oral breathing on skeletal development with a significant constriction of the whole palate. The study group showed a higher and sharper palatal vault at the level of second deciduous molars and of first permanent molars., Conclusions: Children with mouth-breathing pattern showed a significant constriction of the maxillary arch and an increased palatal height when compared with subjects with normal breathing pattern., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Objective: To determine how orthodontic treatment with first premolar teeth extracted and the associated arch dimensional changes in bimaxillary proclination patients affect the upper airway dimensions., Materials and Methods: Pre- and postorthodontic treatment cephalograms and dental casts of 40 bimaxillary proclination patients (ages ranged between 18 and 23 years) were used for this study. Patients were all treated with extraction of the four first premolars. Cephalometric radiographs were used to measure airway dimensions, and dental casts were used to measure the changes in the arch dimensions. A paired t-test was used to detect differences at P < .05., Results: The results showed statistically significant reductions in tongue length (P < .05), posterior adenoids thickness (AD2-H) (P < .05), upper and lower incisor inclination, and lower incisor to A-Pog line (P < .001). Considering the dental cast results, statistically significant reductions in upper arch length, lower arch length, and lower intermolar width were also found (P < .001). The only statistically significant increase was recorded for the upper intercanine width (P < .001)., Conclusions: Extraction of the first premolars for the treatment of bimaxillary proclination does not affect upper airway dimensions despite the significant reduction in tongue length and arch dimensions.

Introduction: The aim of this study was to examine whether there is a relationship between the position of impacted maxillary canines and the morphology of the maxilla., Methods: The palatally impacted canine group included 18 boys and 27 girls with an average age of 12 years 9 months (±2 years 1 month). The buccally impacted canine group comprised 19 boys and 26 girls with an average age of 12 years 2 months (±1 year 4 months). Arch length/intermolar width × 100 was used as the value for comparison of maxillary arch shapes, and palatal vault depth/intermolar width × 100 was used to compare the shapes of palate between the 2 groups. Each category was directly measured from the diagnostic model., Results: Both the arch length/intermolar width × 100 and the palatal vault depth/intermolar width × 100 formulas showed statistically significant differences (P <0.0001), indicating differences in the shape of maxillary arch and the palatal vault between the 2 groups., Conclusions: The shape of the maxillary arch was narrower and longer in the palatally impacted canine group compared with the buccally impacted canine group, and the palatally impacted canine group had a deeper palatal vault than did the buccally impacted canine group., (Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.)

Background: After loss of natural teeth, provision of prosthodontic services almost becomes necessity in the present day living. To provide effective mastication teeth have peculiar forms. To make it more efficient both functionally and biologically, they are arranged in particular geometric manner referred to as dental arch. The objective of this study was to compare the distance between mesial edge of the maxillary central incisors and posterior border of the incisive papilla in dentate individuals with different arch forms., Methods: After sample selection, impressions were made for upper and lower arches and the resultant casts were standardised. Arch forms were assessed by their morphological description. Measurements on cast were recorded for incisive papilla (IP) and maxillary central incisor (CI) distance after securing it on cast surveyor., Results: Ovoid arch form was the most frequently observed arch form both in males (57%) and females (68%) while their combination (Ovoid Square and Ovoid tapered) were the least commonly observed arch forms (4% and 5% each). Gender seems to be important in about 1/4th of the dentate individuals, regarding both the type of the arches and CI-IP distance., Conclusion: Ovoid type of arches was the commonest arch form seen in either sex. There is no significant difference between males and females in 3/4th of dentate individuals, regarding the type of dental arch as well as CI-IP distance.

Recognition of "Jobs Syndrome" disorder may lead to better care. One of the dental manifestations reported is a high arched palate. Measurements of the maxillary arch were made to compare affected Job's patients, unaffected family members, and controls. Measurements of the palate found little difference between the three groups. DMFS, periodontal disease, and oral hygiene were evaluated with little difference between groups.

Introduction: Women of the Padaung tribe in Thailand are known to wear brass neck coils (BNC) all their lives. The purpose of this study was to identify the effects of these coils on facial morphology and dental characteristics., Methods: This study sample included 61 subjects wearing BNC (group I) and 32 subjects not wearing BNC (group II). Each group was subdivided into younger (5-15 years old) and older (more than 15 years old) groups. Facial morphologic variables were assessed by using photographic analysis and direct facial measurements. Dental variables were assessed by model analysis., Results: Total and lower face heights in group I were significantly shorter than in group II (P = .04, P <.001, respectively). Upper and lower lip lengths in group I were significantly shorter than in group II (P = .01, P <.001, respectively). Overjet in group I was significantly larger than in group II (P = .01). Mandibular intercanine width in group I was significantly narrower than in group II (P = .04). Maxillary and mandibular incisor inclinations in the older subset of group I were more proclined than in the older subgroup of group II (P = .04, P = .03, respectively). Palatal height in the older subgroup of group I was less than in the older subgroup of group II (P <.001). Maximum mouth opening in group I was significantly less than in group II (P = .02)., Conclusions: The findings indicated considerable effects on facial morphology and dental characteristics in Padaung women wearing BNC. Deformations could be avoided if they gave up this custom.

In craniofacial surgery and orthodontics, three-dimensional computer models of the dental arch and palate have recently entered usage in diagnosis assessment, treatment planning, case presentations and evaluation of treatment progress and outcome. In this contribution, we show how effective visualisation and evaluation of changes in the size and shape of the dental arch and palate in a given patient can be performed using superimposition of two or more 3D computer models that record the condition before and after treatment. We also present a method of three-dimensional measurement of the dental arch and palate suitable for evaluation of treatment results within retrospective and prospective studies in larger samples of subjects.

The purpose of this study was to investigate changes in the palatal form in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. The hypothesis that orthodontic treatment with premolar extractions changes the palatal form was verified.

The purpose of this study was to investigate changes in arch length, arch area, and irregularity index in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. In general, the maxillary arch exhibited less relapse tendency than did the mandibular arch for both patient groups. In general, the extraction group showed the same relapse tendency as the nonextraction group.

Moiré effect is an optical phenomenon that occurs when two similar arrays of alternately opaque and transparent lines or dots are superimposed upon each other. Superimposition of two such similar, but slightly different, line arrays causes interference between the arrays; the interference results in the formation of moiré fringes. There is a definite relationship between the pitches of the two arrays and the spacing of the fringes. Therefore, given the pitch of one of the arrays and the distance between the moiré fringes, the pitch of the other array can be calculated. The moiré effect can be used to determine the development of cutaneous tumors in a very short time-frame and to assess the measurement of dental eruption within 20 minutes. The 3-D facial, palatal and dental morphology can thus be evaluated very accurately. The CAD/CAM dental technology is actually possible due to the moiré effect.

Objective: To study changes of dental and palatal arch forms between adults and children after rapid maxillary expansion (RME)., Methods: Trans-arch and trans-palatal widths, and molar and palatal angles on plaster models of 47 children and 47 adults were measured pre- and post-treatment with RME., Results: 1. Trans-arch width: Increases of trans-molar and trans-cuspid widths were significantly greater in the child group than those in the adult group, except first and second premolars. In the child group, there was no significant difference of increased widths between posterior teeth and cuspids. But, in the adult group, increased widths in trans-arch of first molars, first and second premolars were significantly greater than those in cuspids. 2. Transpalatal width: Trans-palatal increases at mid-palates and the apex of palates were significantly greater in the child group than those in the adult group. 3. Molar angle: In the child group, no difference existed in the molar group between pre- and post-treament. But, in the adult group, statistical difference existed between pre- and post-treatment. Prior to RME, the molar angle was the same between the child group and the adult group. The molar angle was significantly greater in the adult than that in the child group after RME. 4. Palatal angle: The changes were not of statistical significance in child palatal angles between pre- and post-RME. Significant differences existed in the adult group between pre- and post-RME. Increases of palatal angles were significantly greater in the adult than those in the child group., Conclusion: Significant differences existed between the child and the adult group in forms of dental arches and palatal arches, which focused on the changes of molars and palatal angles after RME.

Dental plaster casts of 97 6-8-year-old and 173 12-year-old Maasai, Kikuyu, and Kalenjin children were studied. The Kikuyu are Bantu, while Maasai and Kalenjin are Nilo-Hamitic subjects. The variables measured were palatal depth (PD) and length (PL); maxillary and mandibular anterior arc circumferences (AC1) and (AC2), respectively; posterior arc circumferences (PC1) and (PC2), inter-canine (CC1), and (CC2); inter-molar (MM1) and (MM2) distances, and mandibular length (ML). The data were analysed using SPSS package. The mean values of all the variables were generally higher in the males compared with the females and significant sex differences in the means (P < 0.01) were found in AC1, PC1, PC2, CC1, CC2, MM1, and MM2 in the 12-year-old subjects. The means of all variables, except PL, ML, PC2, and CC2, increased from 6 to 12 years of age and significant differences in the means for age were found in ML, AC1, PC2, PD, MM1, MM2, and CC1. Mean maxillary inter-molar distance increased with age by 0.17-0.34 mm in the three groups. Mean values of mandibular variables were highest in the Kikuyu, while maxillary variables were highest in the Maasai. The Maasai casts showed a marked decrease in CC2, PC2, AC2, and ML compared with the Kikuyu and Kalenjin. Ethnic and sex differences in the dental arches may be masked by anterior tooth positions that are influenced by the dento-alveolar complex and soft tissues. Corresponding mandibular and maxillary variables were strongly correlated and anterior and posterior arc circumferences were correlated with inter-canine and intermolar distances. Details of the norms for dental arch dimensions and changes with age may allow for appropriate assessment of dental occlusion and treatment planning for Kenyan children.

Statement of Problem: Several factors have been suggested as aids for artificial tooth selection. Numerous methods have been devised for the evaluation of reliable esthetic factors in determining artificial tooth form. There is no universally accepted single esthetic factor that can be used reliably to aid artificial tooth selection., Purpose: This article describes a new method incorporating a computer program to analyze four esthetic factors: form of the face, arch form, palatal contour, tooth shape, and to determine whether there was correlation between tooth, face, and arch forms and palatal contour., Material and Method: Impressions were made of the maxillary dentition of 50 dentate undergraduate dental students with irreversible hydrocolloid impression material and casts formed. A standardized photographic procedure was used to record portrait slides of each subject's face and of maxillary dental arches and central incisors made from dental casts. A comprehensive computer program was developed to correlate esthetic factors by superimposition., Results: Superimposing outline form between face, tooth, and arch showed that for tooth to face form nearly half the comparisons were dissimilar and only 22% corresponded. This is the lowest level of correspondence in this group. Highest correspondence (28%) occurred between arch to face form, followed by arch to tooth form (24%). Arch to tooth showed the lowest level of dissimilarity (32%). For correlation among the four factors across the sample group based on a comparison of classifications in each subject, men tended to dominate tapering classes, whereas women dominated square and ovoid classes., Conclusion: Correspondence of outline forms through superimposition revealed an insignificant correlation between face, tooth, and arch forms. Although this method applies high technology, it does not improve the accuracy of determining shape and size of teeth in an edentulous patient. The cost and complexity of the method of measurement may also make it impractical for common application.

Differences in the dental arch and palate among Taiwan Aboriginals were investigated and compared with Taiwanese and Japanese. Plaster models were taken from 315 Taiwan Aboriginal adults, 185 Taiwanese and 426 Japanese between 1979 and 1989, and various dimensions were measured. There were no clear differences in the characteristics of the dental arch and palate between Taiwan Aboriginal tribes. However, they were found to differ from those of Taiwanese and Japanese. In a dendrogram constructed from a cluster analysis, two major clusters were found. Among males, the first cluster contained Paiwan and Rukai, the second contained Japanese, Taiwanese, Ami and Bunun. Among females, the first contained Japanese, Taiwanese, Rukai and Paiwan, the second contained Ami and Bunun. The Ami were close to Bunun and the Paiwan were close to Rukai among both males and females. These results indicate that Ami and Bunun, and Paiwan and Rukai, respectively, have close affinities.

The purpose of this survey was to determine whether children in northern Finland had different dental arch dimensions from children in southern Finland. Dental casts of 9-year-old healthy children from Helsinki (southern Finland) and from Oulu and Sodankylä (northern Finland) were measured. Each group contained 41 subjects who had received no orthodontic treatment. The children from Sodankylä and Oulu had narrower dental arches and greater palatal heights than those from Helsinki. The lengths and perimeters of dental arches were significantly shorter in the children from Sodankylä than in those from Helsinki. We suggest these differences could have resulted from adaptation to different climatic conditions, affecting modes of breathing.

Using Moiré topography, the forms of the dental arch and palate of males and females were compared. This was carried out in Fukien province, Taiwan. The materials used consisted of plaster casts of the upper dentitions of 65 males and 69 females with normal occlusion, aged from 20 to 22 years. The results are as follows: 1. The standard form of the upper dental arch represented by a pentagon is shown in Table 1 and in Fig. 3. 2. The dental arch of the male was larger than that of the female, the difference being significant for the anterior and posterior widths of the arch. 3. The correlation coefficients were generally lower in the female than in the male. This was especially true with regard to the size of the anterior portion of the female dental arch. In the posterior portion, there was no correlation between the dental arch length and dental arch width of either sex. 4. The distance from the origin (F) to the papilla incisiva was 23.47 mm in the male and 23.67 mm in the female. The number of moiré band in the bottom of the palate at the origin from the basal plane was 12.89 in the male and 12.73 in the female. There were no significant differences in these two measurements between sexes. 5. On the vertical section of the palate, the anterior portion of the palate of the female was deeper than the male. However, in the posterior portion the male was deeper and wider in the palate morphology than the female. The vertical section in the palate of the male was similar in form to that of the female at the midpoint between the anterior and posterior portions, the canine and/or first premolar. 6. The horizontal section of the palate showed that the distance from the origin to the canine and/or to the first premolar were similar in both sexes at any palate depth.

Studies of the dental arch and the palate have progressed from two-dimensional to three-dimensional analysis. However, many points still need clarification in this field even though the fundamental structure of arch and palate have a common function in connection with mastication. The present study, using three-dimensional measurements of the palate, endeavors to clarify the differences in palatal morphology as these are affected by the changes in the dental arch morphology. Casts were made using 62 males between the ages of 20-25. Only those casts which were considered to represent normal occlusion of the upper dentition were selected for use in this study. Photographs of the casts were studied using the Moiré topographical method with a grid of 0.5 mm. Seven points were selected for measurement purposes (figs. 2 and 3). Based on these points, the seven distances were used in this study. Measuring of the palate was performed in the following manner: lines were drawn radially from the origin (F) to the most lingually protrusive point on the gingiva of each of the 12 teeth from the right first molar round to the first molar on the left side. The points of mergence by these lines with every second line (2 mm deep) of the Moiré pattern were fed into a digitizer. The results were summarized as follows: 1. The anterior, posterior and complete arch chords were 23.73 mm, 19.93 mm and 41.68 mm respectively. The anterior, posterior and complete arch lengths were 14.14 mm, 19.98 mm and 34.12 mm respectively. The anterior and posterior arch widths were 38.02 mm and 50.73 mm respectively. 2. As for the correlation coefficients, there was a correlation between the lengths and widths of the anterior portion, but not for the posterior. 3. The length from the origin (F) to the papilla incisiva was 25.4 mm, and the depth of the palate at the origin (F) was 13.4 mm on the average. 4. In the vertical cross section of the palate for each tooth, the slope line of the palate gradually increased from the incisors to the first molars, but the amount varied between the anterior and posterior portions of the maxillary dentition. Also, the line of the palate converged at one point about 11 mm from the origin (between lines 9 and 11 on the Moiré pattern). 5. In the horizontal cross section of the palate, the shape of the palate was almost semi-circular in the range of Moiré lines 9-11 with the origin at the center.(ABSTRACT TRUNCATED AT 400 WORDS)

Changes of maxillary arch dimensions were studied longitudinally until maturity, after palatal surgery was performed on 37 beagle dogs at different ages. The dogs were divided into three experimental groups, a sham group, and a control group. At the age of 6, 16, or 25 weeks in the experimental groups, we created a soft-tissue cleft in the medial region of the palate, made relaxation incisions, and elevated and closed the mucoperiosteum in the midline, thus leaving two areas of denuded bone adjacent to the dentition. We made dental casts regularly until the age of 37 weeks, and studied maxillary arch dimensions. Surgery performed before or during the transition of teeth did not change maxillary arch dimensions in the deciduous dentition, but after the transition, the increase in arch width in the pre-molar region was reduced. Surgery performed after completion of the permanent dentition did not change maxillary arch dimensions. Delay of palatal surgery until the transition of teeth was completed favored normal development of the maxillary dental arch.

Buccal shields inserted in the mouths of 30-day-old Sprague-Dawley rats displaced the buccal musculature away from the maxillary molar teeth. Intermolar distances increased significantly (P less than 0.02) 15 days following insertion of the appliance, thereafter decreasing with time. Histologically, at the level of the first molars, ossification of the sutural cartilage occurred earlier than in control sutures. While different interpretations are given to explain this result, the adaptive nature of secondary cartilage in the intermaxillary suture of the rat was demonstrated. This adaptation may be limited by the nature of mechanical stress exerted upon, and/or the growth potential, of the suture.

The changes of the dental arch form after the tooth movement and the sequential changes occurred on the palate during orthodontic treatment were examined in the coordinate system based on the standard point at the palatal vault. The subjects selected for this study were 20 patients of Angle Class II div. 1. Both left and right maxillary premolars were extracted and an edgewise appliance had been treated. The plaster models prepared before and after treatment were used for materials. Only suitable materials were measured as a result of an examination of the reproducibility of the palatal core at the palatal vault. Results obtained were as follows: 1. It was suggested that the dental arch and the palate was mutually effected on each other in the arch length and the arch width. 2. The morphological changes in the dental arch and the palate due to orthodontic treatment was discussed on the basis of the results of Fourier analysis. The dental arch and the area from F division to J division were significantly smaller after orthodontic treatment than before it. The shape became closer to a semicircle. 3. Values representing morphological changes in the dental arch and J division were similar and values representing morphological changes in the other division were getting smaller as the area being close to the palatal vault.

Statistical comparison of arch width, length and palatal height with age, sex, orthodontic treatment and extractions finds little correlation except a tendency for larger dimensions in males, especially in palatal width, and differences related to postextraction drift.