OBJECTIVETo study the relationship between the mesiodistal tipping degree of maxillary and mandible posterior teeth and different vertical facial skeletal types of subjects with normal occlusion.

METHODS163 subjects with normal occlusion were selected, lateral cephalograms were taken and divided into three different facial skeletal types. The difference of the mesiodistal tipping degrees and intersection angles of upper and lower posterior teeth between the three different facial skeletal types were analyzed.

RESULTSAmong 163 subjects, vertical growth pattern, average growth pattern and horizontal growth pattern were 24, 96 and 43 respectively. There were statistic differences of mesiodistal tipping degrees of the first and second maxillary and mandible premolar and the first permanent molar between vertical growth and horizontal growth pattern, horizontal growth and average growth pattern (P < 0.05). But there were no statistically significant differences between vertical growth and average growth pattern (P > 0.05). The differences of the maxillary and mandible posterior teeth's intersection angle among three vertical facial skeletal types had no statistic significance (P > 0.05).

CONCLUSIONDifferent vertical facial skeletal type has its own normal and coordinated posterior teeth mesiodistal tipping degrees.

Dental Occlusion ; Humans ; Mandible ; anatomy & histology ; Maxilla ; anatomy & histology ; Tooth

UNLABELLEDTo evaluate the effects of preadjusted bracket base shape, the morphology of tooth surface where bracket locates, and the suitability relevant to location of bracket on the preadjusted edgewise appliance technique. 1 vertical curve and 3 horizontal curves of the clinical crown surface of anterior teeth and bicuspid teeth were measured with the precise contour instrument on the 60 plaster models of the subjects who have normal occlusion in Sichuan province. It was found that variation of identical curve exists at the different heights between the teeth and between the individuals; the surface of the central zone of tooth-crown gradually protrudes from incisors to bicuspid teeth in the vertical direction, and the mesial contour of cuspid is more prominent than the distal in the horizontal direction.

CONCLUSIONThe 4 mm X 3 mm contour of the vestibular central zone of identical tooth-crown in different individuals is fairly stable; it is suitable for the location of preadjusted brackets. The vertical shifts of brackets could change the preadjusted torque value and the design of cuspid bracket should have the distinction between mesial and distal shape.

Bicuspid ; anatomy & histology ; Dental Occlusion ; Humans ; Incisor ; anatomy & histology ; Tooth Crown ; anatomy & histology ; Torque

Micro-hardness of human teeth was measured by micro hardnessmentry at different depths i.e. enamal, enamelo-dentinal junction and dentin. A simulated dental friction test was conducted of respectively in these three areas, opposing pure titanium ball under a modified fretting machine. The results showed that micro-hardness is 320.40 +/- 22.77 HV of enamal, 232.26 +/- 32.31 HV of enamelo-dentinal junction, and 61.17 +/- 9.42 HV of dentin (P < 0.05). Wear depth is 17.33 +/- 0.58 microns of enamal, 49.44 +/- 16.47 microns of enamelo-dentinal junction and 95.20 +/- 15.07 microns of dentin(P < 0.05). Wear resistance of enamal is much better than that of dentin's. This preliminary investigation should be very useful in clinical applications.
Adult ; Hardness ; Hardness Tests ; methods ; Humans ; Tooth ; anatomy & histology ; physiology

OBJECTIVEThe characteristics of lip-mouth region including the soft and hard tissues in smiling position with frontal fixed position photographic computer-aided analysis were studied.

METHODSThe subjects were 80 persons (40 male and 40 females, age range: 17 to approximately 25 years) with acceptable faces and individual normal occlusions. The subjects were asked to take maximum smiling position to accept photographic measurement with computer-aided analysis.

RESULTSThe maximum smile line could be divided into 3 categories: low smile line (16.25%), average smile line (68.75%), and high smile line (15%).

CONCLUSIONThe method adopting maximum smiling position to study the lip-month region is reproducible and comparable. This study would be helpful to provide a quantitative reference for clinical investigation, diagnosis, treatment and efficacy appraisal.

Adolescent ; Adult ; Anthropometry ; Dental Occlusion ; Female ; Humans ; Lip ; anatomy & histology ; Male ; Mouth ; anatomy & histology ; Smiling ; Tooth ; anatomy & histology

Dental Pulp Cavity ; anatomy & histology ; Humans ; Male ; Maxilla ; Middle Aged ; Molar ; anatomy & histology ; Odontometry ; Tooth Root ; anatomy & histology

OBJECTIVETo investigate the correlation among the morphology of crown, alveolar ridge crest and gingiva in maxillary anterior region of adults and to provide anatomical basis for clinical implant esthetics.

METHODSSixty Han-Chinese with healthy peridontium were selected in this study. The curvature of labial alveolar crest, the length and height of inter-proximal bone were measured on 3-D model reconstructed from cone-beam CT (CBCT) images, and the curvature of free gingiva, the width and height of inter-dental papilla and central incisor crown were evaluated on casts. The ratio of crown width to height was ranked and the 10 ranked highest were categorized as group Short-Wide (SW), the 10 ranked lowest were selected as group Long-Narrow (LN).

RESULTSIn maxillary anterior region, the curvature angle of both alveolar crest and marginal gingiva were significantly different among different tooth regions, but the alveolar and gingival curvature was significantly correlated in the same region (P < 0.05). The morphology of inter-proximal bone and papilla was significantly correlated (P < 0.01), except the region between central and lateral incisors (P = 0.625, P > 0.05). Compared to group SW, group LN formed a pronounced scalloped contour of gingival margin (P = 0.002) and slender inter-dental papilla (P = 0.000).

CONCLUSIONSThe free gingival curvature and inter-dental papillary morphology are significantly correlated with the morphology of crown and alveolar ridge crest in maxillary anterior region of Han-Chinese. Individuals with long-narrow crown, pronounced scalloped marginal gingiva and slender inter-dental papilla are susceptible to risk implant esthetics.

Alveolar Process ; diagnostic imaging ; Crowns ; Gingiva ; anatomy & histology ; Humans ; Incisor ; anatomy & histology ; Maxilla ; Radiography ; Tooth Crown ; anatomy & histology

OBJECTIVEThe purpose of this study was to investigate the center height of clinical crowns and the difference among individuals, together with the regularity of the Spee curve in mandible and compensating curve in maxilla for the people with normal occlusion in Chengdu area.

METHODSThe data were derived from systematically collected people with normal occlusion in Chengdu area, including 36 males and 39 females (ranged from 18 to 35 years). The values of center height of clinical crowns, the depths of Spee curve and curve formed by the center of clinical crowns in mandible were obtained by measurement. Afterwards, the distribution of the center height of clinical crowns was analyzed, as well as the depth of curve formed by the center of clinical crowns in mandible and its correlation with depth of Spee.

RESULTS(1) The distribution of the center height of clinical crowns accord with normal distribution and the standard deviation was minor(< 0.5 mm); (2) There was no statistical difference between male and female for the center height of clinical crowns; (3) The depth of curve formed by the center of clinical crowns in mandible and the depths of Spee curve showed highly correlation (gamma = 0.986, P < 0.0001).

CONCLUSION(1) The difference of the center height in clinical crowns among individuals with normal occlusion in Chengdu area was minor; (2) There was no significant difference on the center height in clinical crowns between male and female; (3) Provide a recommended bracket placement chart suitable for people of Chengdu area in clinical practice; (4) The brackets of the pre-adjusted appliance should be placed in the center of clinical crowns, despite some adjustment are needed in some special circumstances.

Adolescent ; Adult ; Anthropometry ; Dental Arch ; anatomy & histology ; Dental Occlusion ; Female ; Humans ; Male ; Mandible ; anatomy & histology ; Maxilla ; anatomy & histology ; Orthodontic Brackets ; Reference Values ; Tooth Crown ; anatomy & histology

The purpose of this study was to evaluate the effect of age on the ratio of pulp cavity/tooth width (P/T ratio) in healthy cats. The dental radiographs of 32 cats (16 males and 16 females) were generated with a digital dental X-ray unit with the animals under general anesthesia. Standardized measurement of the canine teeth was performed by drawing a line on the radiograph perpendicular to the cementoenamel junction (CEJ) of the tooth. There was an inversely proportional correlation between chronological age and the P/T ratio. Moreover, a strong Pearson squared correlation (gamma2 = 0.92) was identified by the curved regression model. No significant differences in the P/T ratio based on gender or breed were found. These results suggest that determination of age by P/T ratio could be clinically useful for estimating the chronological age of cats.
Age Determination by Teeth/*veterinary ; Animals ; Cats/*physiology ; Dental Pulp Cavity/anatomy & histology/*radiography ; Female ; Male ; Tooth/anatomy & histology/*radiography

OBJECTIVETo observe the results of surgical crown lengthening procedure and the factors which affected the success of the surgery.

METHODSCrown lengthening surgery was performed on 27 teeth. The distance between margin of tooth and bone crest (MT-B) was obtained greater than 4 mm during the surgeries on 10 teeth which were considered as satisfying group. The other 17 teeth were as temporized group with MT-B < or = 3 mm. The position of the tooth margin was evaluated before surgery, immediately after suturing, and at 4 - 6 weeks after surgery. The occlusal force and tooth mobility were measured immediately after restoration, at 3 and 6 months after surgery.

RESULTSMT-B was obtained > or = 4 mm and all margins and sites of the teeth were exposed in satisfying group (10/10). At least 1 site with MT-B < 3 mm in temporized group in which there still were 11 sites (16%) in 5 teeth (29%) with subgingival tooth margin at 4 - 6 weeks after surgery. There were more teeth showing increased mobility in temporized group (12/17) than in satisfying group (1/10) after surgery (P < 0.05). The occlusal force of the teeth after surgery and restoration in temporized group was significantly lower than that of their counterpart teeth (P < 0.01), but it was not the case in satisfying group (P > 0.05).

CONCLUSIONSIt is suggested that ideal exposure of tooth margin could be obtained if 4 mm from tooth margin to alveolar crest could be created during the crown lengthening surgery. The teeth both with 4 - 5 mm subgingival margin sites and factors limiting surgical performance are not the suitable indications for the surgical crown lengthening.

Alveolectomy ; Crown Lengthening ; methods ; Follow-Up Studies ; Gingiva ; anatomy & histology ; Humans ; Periodontium ; anatomy & histology ; physiology ; Prospective Studies ; Tooth Crown ; pathology

OBJECTIVE: To analyze the esthetic proportions of maxillary anterior teeth in term of the apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown in 120 Chinese adults. METHODS: Maxillary gypsum casts were obtained from the dental laboratories of stomatological hospitals in North China, Southeast China, and Southwest China, according to the inclusion criteria and exclusion criteria. Standardized digital photographs of each cast were recorded. The apparent widths and actual widths and heights of the central incisors, lateral incisors and canines were determined by ImageJ software for the calculation of apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown. The ideal apparent widths proportion (Golden proportion and Preston proportion) and width/height ratio (0.80) were tested. The gender, arch side, and regional differences were investigated. RESULTS: The apparent widths proportion of the lateral/central incisor was 0.724±0.047, of the canine/lateral incisor was 0.814±0.092. The width/height ratio of the central incisor was 0.848±0.072, of the lateral incisor was 0.834±0.094, of the canine was 0.883±0.098. The esthetic proportions were different from the predicted ideal ratio (P < 0.001). The apparent widths proportion of lateral/central incisor was significantly larger in the right side than that in the left side (0.730± 0.044 vs. 0.718±0.050), and was significantly smaller in North China than that in Southwest China (0.711±0.051 vs. 0.731±0.044). The width/height ratio of the central incisor was significantly larger in the female than that in the male (0.855±0.074 vs. 0.835±0.068), and in the right side than that in the left side (0.855±0.073 vs. 0.842±0.072). The width/height ratio of the lateral incisor was significantly larger in the female than that in the male (0.843±0.097 vs. 0.817±0.084). CONCLUSION The apparent widths proportion of adjacent teeth and the width/height ratio of the clinical crown in Chinese adults are different from the foreigner's. The esthetic proportion parameters have significant population specificity, and the measurements cannot be generalized as well as it should be applied with caution.
Adult ; Asians ; China ; Cuspid ; Esthetics ; Esthetics, Dental ; Female ; Humans ; Male ; Maxilla/anatomy & histology* ; Odontometry ; Tooth Crown/anatomy & histology*