OBJECTIVE: To verify the consistency between the digital manufacturing simple intraoral Gothic arch-tracing device and the traditional intraoral Gothic arch-tracing device in determining the centric relation of complete dentures restoration. METHODS: Ten outpatients with edentulous jaws were selec-ted, and the centric relation of the patients was determined by digital manufacturing of simple intraoral Gothic arch-tracing device (T1) and traditional intraoral Gothic arch-tracing device (T2); the difference of clinical operation time between the two methods was recorded; the upper and lower edentulous jaw plaster models were scanned with two kinds of centric relation, the Standard Triangle Language (STL) files imported into Geomagic studio software to apply the best fitting of multiple points of the both upper jaw models, the fitted STL files imported into the 3 shape viewer software, and the maximum position deviations of the vertical, labial (buccal) and lingual directions of the mandibular midline area and molar areas in T1 and T2 groups measured. During the clinical complete dentures try-in, we observed whether there was midline deviation in the mouth of T1 group and T2 group, and whether the occlusion of posterior teeth was stable or not. RESULTS: The mean time spent on determining the centric relation of T1 and T2 groups was (41.90±2.64) min, (57.50±2.37) min respectively. Paired t test was conducted in the two groups, P < 0.01 with significant statistical difference; The mean maximum position deviation between T1 group and T2 group of the midline mandibular region in labial lingual direction was (0.32±0.14) mm, that was (0.40±0.23) mm in vertical direction; the mean maximum position deviation of molar area in buccal lingual direction was (0.35±0.23) mm and that was (0.33±0.20) mm in vertical direction. In the vertical and horizontal directions, the maximum position deviation of mandibles between group T1 and group T2 was controlled within 0.5 mm. In the process of clinical complete dentures try-in, there was no deviation from the center line of dentures. There was not warping, swinging and other poor stability phenomena in T1 and T2 groups. CONCLUSION The digital manufacturing of simple intraoral Gothic arch-tracing device can be used to determine the centric relation of complete dentures, which can not only save time of clinical operation, but also ensure the accuracy of the centric relation.
Humans ; Centric Relation ; Jaw Relation Record/methods* ; Denture, Complete ; Mouth, Edentulous ; Jaw, Edentulous

OBJECTIVETo study the edentulous patients facio-maxillary characters, and discuss the base of recording jaw relation by swallowing action.

METHODSForty-three edentulous patients were included in this study, age ranged from 57 to 70 yr, with new comfortable full dentures. Two lateral cephalograms for one patient were taken by SIRONA digital X-ray dental system, one of which was centric occlusion with full denture, another was the end position of swallowing action without denture.

RESULTSThe vertical facial dimensions of male were a little more than that of female. The ratio of lower front facial height/upper front facial height was about 6/5, angle S-N-Po was about 78 approximately 80 degrees. These data may be useful for dentists to make diagnoses if the jaw relation is right or not. Both in vertical or anterior-posterior (horizontal) dimension, the differences between two groups (two actions in one patient) were not significant. It showed that two positions of two actions were the same.

CONCLUSIONSThe SIRONA digital X-ray dental system for cephalometry was swift, and had its own characters. The way of swallowing and occluding is one of efficient methods to record the jaw relation of edentulous patients veraciously and naturally.

Aged ; Cephalometry ; methods ; Deglutition ; Female ; Humans ; Jaw Relation Record ; Jaw, Edentulous ; diagnostic imaging ; Male ; Middle Aged ; Radiography, Dental, Digital

OBJECTIVEThe purpose of this study was to make a comparison between extraction and non-extraction orthodontic treatment results concerning teeth alignment, occlusal relation, facial profile and treatment interval.

METHODS39 extraction-non-extraction borderline cases were selected by 5 orthodontic specialists through reviewing their pre-treatment records. 5 specialists were then asked to rank the results by marking the post-treatment record of each case. And then the samples were divided into different groups according to extraction, non-extraction and extraction pattern by reviewing case history.

RESULTSNo statistically significant difference was found in teeth alignment, overbite and overjet, midline symmetry, lateral occlusal relation and treatment intervals. However, the post-treatment facial profile of extraction groups obtained higher marks from 5 specialists (P = 0.001).

CONCLUSIONWhile both extraction and non-extraction treatment can achieve comparable results in teeth alignment and occlusal relation with equivalent time interval in borderline cases, extraction treatment, whatever extraction of four first premolars or second premolars is performed, can achieve better facial profile.

Child ; Dental Occlusion ; Female ; Humans ; Jaw Relation Record ; Male ; Malocclusion ; therapy ; Orthodontics, Corrective ; methods ; Retrospective Studies ; Tooth Extraction

The article introduces a new method for three-dimensional reproduction of edentulous dental casts, and wax occlusion rims with jaw relation by using a commercial high-speed line laser scanner and reverse engineering software and evaluates the method's accuracy in vitro. The method comprises three main steps: (i) acquisition of the three-dimensional stereolithography data of maxillary and mandibular edentulous dental casts and wax occlusion rims; (ii) acquisition of the three-dimensional stereolithography data of jaw relations; and (iii) registration of these data with the reverse engineering software and completing reconstruction. To evaluate the accuracy of this method, dental casts and wax occlusion rims of 10 edentulous patients were used. The lengths of eight lines between common anatomic landmarks were measured directly on the casts and occlusion rims by using a vernier caliper and on the three-dimensional computerized images by using the software measurement tool. The direct data were considered as the true values. The paired-samples t-test was used for statistical analysis. The mean differences between the direct and the computerized measurements were mostly less than 0.04 mm and were not significant (P>0.05). Statistical significance among 10 patients was assessed using one-way analysis of variance (P<0.05). The result showed that the 10 patients were considered statistically no significant. Therefore, accurate three-dimensional reproduction of the edentulous dental casts, wax occlusion rims, and jaw relations was achieved. The proposed method enables the visualization of occlusion from different views and would help to meet the demand for the computer-aided design of removable complete dentures.
Analysis of Variance ; Computer-Aided Design ; Dental Models ; Denture Design ; Denture, Complete ; Dimensional Measurement Accuracy ; Humans ; Imaging, Three-Dimensional ; methods ; Jaw Relation Record ; Lasers ; Mouth, Edentulous ; rehabilitation ; Waxes

OBJECTIVEThe purpose of this study was to obtain the normal value of McNamura analysis for Chengdu adolescents with normal occlusion of early permanent dentition.

METHODSMcNamara analysis was conducted on the basis of the lateral cephalograms of 67 Chengdu adolescents with normal occlusions, and the obtained data was compared with that of Shanghai adolescents and McNamara.

RESULTSThere was no difference in the normal value of McNamara analysis between male and female Chengdu adolescents. The Comparative results between Chengdu and Shanghai adolescents indicated significantly larger values of Shanghai adolescents in effective middle facial lengths, mandibular lengths and lower anterior facial heights. The vertical distances from the upper incisor to point A and, from the lower incisor to A-Po line of Chengdu adolescents were larger than those of white adolescents.

CONCLUSIONThere is significantly difference in values of normal occlusions of McNamara analysis among different regions and different races.

Asian Continental Ancestry Group ; Cephalometry ; methods ; Child ; China ; Dental Occlusion ; Diagnosis, Computer-Assisted ; Face ; anatomy & histology ; Female ; Humans ; Jaw Relation Record ; Male ; Maxillofacial Development ; Radiography ; Reference Values ; Skull ; diagnostic imaging