Mixed dentition space analysis in a Thai population. (33/1158)

This study produced simple linear regression equations to be used for mixed dentition space analysis for males and females, and sexes pooled in a population living in northeastern Thailand. Measurements of teeth were made to within 0.01 mm on the dental casts of 215 boys and 215 girls (mean age 15.7 years). All dentitions were required to be free of any signs of dental pathology or anomalies. It was found that males had significantly larger teeth than females as represented by summations of mandibular incisor, canine, and premolar widths. ANOVA of regression indicated a close relationship between mandibular incisor summation and corresponding summations of canine and premolars. The low coefficients of determination (r2) of the regressions ranged between 0.29 and 0.42, and were higher for females than males, which might be attributable to the ethnic diversity of the sampled population. The regression equations produced predictions of mesio-distal width summations for maxillary and mandibular canine, and premolar arch segments that were slightly different from other reported Asian studies. Moyers' prediction tables at the 50th percentile were found to under-estimate tooth size summation compared with the present investigation. The predictions from simplified regression equations matched well with those of this study for sexes pooled, and for males and females separately.  (+info)

Analysis of dental casts of 6-8- and 12-year-old Kenyan children. (34/1158)

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.  (+info)

The prenatal cranial base complex and hand in Turner syndrome. (35/1158)

From early childhood, Turner syndrome patients have a flattened cranial base, maxillary retrognathism, and short hands. There are, however, no studies that show when these genotype-determined abnormalities occur prenatally. The purpose of the present study was to measure craniofacial profile and hand radiographs of second trimester foetuses with Turner syndrome and compare the results with similar measurements from normal foetuses. The subjects consisted of 12 Turner syndrome foetuses, gestational age (GA) varying between 15 and 24 weeks, and crown-rump length (CRL) between 108 and 220 mm. The mid-sagittal block of each cranium was analysed as part of the requested brain analysis (pituitary gland analysis). This block and the right hand from seven foetuses were radiographed, and the skeletal maturity of the cranial base complex, i.e. the cranial base and the maxilla, was evaluated from the profile radiographs. Shape and size measurements in the cranial base were performed, and compared with normal values according to cranial maturity and to CRL. The cranial base angle in Turner syndrome was greater and the maxillary prognathism was reduced compared with the normal group. The dimensions in the cranial complex and in the hand showed that the bone lengths and distances in relation to CRL were generally smaller compared with normal foetuses. This investigation showed that the abnormal shape of the cranial base complex and the short hands in Turner syndrome are present prenatally.  (+info)

A comparative micro-topographic study of the buccal enamel of different tooth types. (36/1158)

The aim of this study was to perform an in vitro examination of the etch pattern achieved on the orthodontic bonding area (OBA) of different tooth types, and to compare the extent and definition of etch achieved. Six examples of each permanent human tooth type were studied. These were collected from adolescents. A standardized etch regime was employed on the OBA and the etch pattern examined under the scanning electron microscope. The degree of definition of etch achieved on every third enamel prism was evaluated. Results showed that the extent of etch achieved decreased toward the distal end of each arch and was significantly less on the first molars (covering <2% OBA) than on the incisors (covering >90% OBA). It was also noted that the degree of definition became poorer towards the distal end of the arches and was worst on the mandibular molars. It is suggested that the etched enamel morphology of different tooth types could affect composite resin bond strengths. Consequently, this feature could effect the clinical survival of orthodontic brackets and contribute to the higher failure rate of brackets on posterior teeth.  (+info)

Radiographic factors affecting the management of impacted upper permanent canines. (37/1158)

The aim of the investigation was to evaluate which radiographic factors influenced the orthodontists' decision whether to expose or remove an impacted upper permanent canine and was a retrospective, cross-sectional design. The sample consisted of all radiographic records of patients referred to the Orthodontic Department at Manchester University Dental Hospital with impacted upper permanent canines between 1994-1998 (n = 44). The following canine position measurements were made from the OPG: angulation to the midline, vertical height, antero-posterior position of the root, overlap of the adjacent incisor, and presence of root resorption of adjacent incisor(s). The labio-palatal position of the impacted canine was assessed from the lateral skull radiograph. Whether the impacted canine had been exposed and orthodontically aligned or removed was also recorded. Stepwise logistic regression analysis showed that the labio-palatal position of the crown influenced the treatment decision, with palatally positioned impacted canines more likely to be surgically exposed and those in the line of the arch, or labially situated, removed (P < 0.05). Additionally, as the canine angulation to the midline increased, the canine was more likely to be removed (P < 0.05). The orthodontists' decision to expose or remove an impacted upper permanent canine, based on radiographic information, seems to be primarily guided by two factors: labio-palatal crown position and angulation to the midline.  (+info)

Effects of a three-dimensional bimetric maxillary distalizing arch. (38/1158)

This study aimed to investigate the dental effects of a three-dimensional (3D) bimetric maxillary distalizing arch. The Wilson rapid molar distalization appliance for Class II molar correction was used in 14 patients (10 girls and four boys with a mean age of 12.18 years). The open coil springs were activated with bent Omega stops and Class II intermaxillary elastics. The mandibular anchorage was gained by a 0.016 x 0.016 utility arch with a 3D lingual arch or a lip bumper with a standard lingual arch. The lateral cephalograms taken before and after treatment formed the material of the research. A Wilcoxon test was used to statistically evaluate the treatment effects. The results showed that the distal tipping of the maxillary first and second molars, and first and second premolars and canines were statistically significant. Significant distal movement occurred in all posterior and canine teeth. The maxillary first molar distalization was found to be 3.5 mm. The maxillary incisor showed significant proclination and protrusion. The decrease in overbite was found to be statistically significant. The mandibular plane angle significantly increased by a mean of 0.5 mm. In addition, significant soft tissue changes were observed.  (+info)

Management of extensive carious lesions in permanent molars of a child with nonmetallic bonded restorations--a case report. (39/1158)

The badly decayed molar teeth of a 12-year-old were restored using resin composite and ceramic restorations. The maxillary first left permanent molar, which had an extensive carious lesion that had destroyed most of the coronal hard tissues of the tooth, was restored to shape and function with a heat-treated resin composite onlay restoration. The restoration was followed up for two years. The mandibular right first molar had a failing large amalgam restoration with extensive recurrent caries. After a three-month period of pulp-capping, the tooth was restored with a bonded ceramic onlay restoration. A nine-month follow-up of this restoration is provided. The maxillary right first molar, which also had a failing large amalgam/resin composite restoration, was restored with a direct resin composite restoration. Under traditional treatment regimens, these extensive cavities would have been treated using more invasive procedures such as pin-retained restorations or elective root canal therapy, post placement, core build-up and crowning. Bonded non-metallic restorations avoid the trauma, time and cost that accompany such extensive procedures and offer a more conservative approach.  (+info)

A modified technique for direct, fibre-reinforced, resin-bonded bridges: clinical case reports. (40/1158)

This article presents new modifications to the clinical technique of fabricating directly applied resin-bonded fibre-reinforced bridges. Torsional and flexural strength is achieved by means of a reinforced polyethylene fibre ribbon substructure surrounded by laminated layers of microhybrid and microfilled resins. The modifications provide a simple method for creating a better pontic-ridge relation and improved overall esthetics. Early clinical experience suggests that this technique has the potential to give patients a relatively conservative, esthetic and periodontally noninvasive alternative for anterior tooth replacement.  (+info)