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At least 541 records · Page 30Linked to original sources
PubMed2001

Do condensable composites help to achieve better proximal contacts?

OBJECTIVES: Obtaining acceptable contact areas with adjacent teeth is a significant challenge when placing direct resin composite in Class II preparations. It was the purpose of this laboratory study to evaluate the influence of the type of resin composite ('packable' vs conventional) and of the matrix system on the quality of the proximal contact area in Class II composite restorations. METHODS: A standardized DO cavity was prepared in 170 frasaco teeth. Two operators each filled 85 teeth in the same frasaco model using four resin composites [Solitaire (S), Surefil (Su), P60, Z100], three matrix systems [Automatrix (A), Palodent (P), Lucifix matrix (L)] and one hand instrument specially designed to achieve better proximal contacts [Belvedere Composite Contact Former (B)]. The teeth were subdivided into 17 groups (Z100/1-A, Z100/1-P, Z100/1-L, S-A, S-P, S-L, Z100/1-A-B, Z100/1-L-B, Su-A, Su-P, Su-L, P60-A, P60-P, P60-L, Z100/2-A, Z100/2-P, Z100/2-L). Each operator made five fillings of each group. The quality of the proximal contacts was assessed by measuring the maximum mesio-distal (M-D) diameter of the restored teeth using a digital micrometer and the tightness of the proximal contact area using standardized metal blades. All data were analyzed using two-way ANOVA and Bonferroni/Dunn's test for multiple comparisons with a significance level of P<0.05. RESULTS: Regarding the matrix system, a significant larger M-D diameter and a stronger proximal contact area was achieved with the Palodent matrix system. The use of the Belvedere Composite Contact Former together with Lucifix matrix and Automatrix contributed to significantly stronger proximal contact areas. Concerning the type of resin composite, no significant differences were noted for both evaluation criteria when Palodent was used. Using Automatrix or Lucifix matrix, the more condensable resin composite P60 scored slightly better than Surefil and Z100. There was no operator effect. Both operators underwent a learning process. The longer they worked with a specific material/technique, the better proximal contacts they achieved. SIGNIFICANCE: The best proximal contact areas in Class II composite restorations were obtained using a sectional matrix system. The 'packability' of the resin composite did not help to achieve better proximal contacts.

Analysis of Variance↗
PubMed2000

Clinical crown length changes from age 12-19 years: a longitudinal study.

OBJECTIVE: The objective of this study was to investigate the relationship between age, gender and clinical crown length using a longitudinal study design. METHOD: Four hundred and fifty-six sets of study models initially obtained for a large prospective longitudinal cohort study of orthodontic needs were examined. Each set of models corresponded to subjects at three different ages: 11-12, 14-15 and 18-19years old. The clinical crown height of the maxillary right central incisor (11), maxillary right canine (13), maxillary left lateral incisor (22) and mandibular left central incisor (31) was measured from gingival crest to the incisal edge using digital calipers. RESULTS: Analysis revealed a significant (p<0.0001) age effect on crown length for all four teeth investigated. A significant gender effect was found in relation to the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor. Pairwise comparisons of the means for each age group for the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor revealed significant (p<0. 0001) increases in clinical crown length between each assessment period. CONCLUSION: The findings of the present study indicate that, the process of passive eruption, resulting in increased clinical crown length appears to continue throughout the teenage years. This finding is considered to be of importance to the clinician making treatment decisions for teenagers and young adults requiring treatment in the anterior segments of the mouth.

Adolescent↗
PubMedDate not supplied

Ultimate tensile strength of PDL of molars in rats after 1-hydroxyethylidene-1,1-bisphosphonate injections.

OBJECTIVES AND METHODS: Administration during root formation of a bisphosphonate, 1-hydroxyethylidene-1,1-bisphosphonate (HEBP), at a dose corresponding to 10 mg P/kg body weight, has been found to interfere with the formation of acellular cementum in rats. The purpose of this study was to measure the force required to extract a tooth lacking normal acellular cementum, and to correlate this force and the ultimate periodontal strength with the morphology of the periodontal tissues at different time intervals after single or multiple injections of HEBP. RESULTS: A single injection of HEBP given during root formation inhibited the formation of acellular cementum and resulted in a temporary reduction of the extraction force and the ultimate tensile strength. Ninety days after the injection of HEBP, both parameters were the same as in the controls. The increase in extraction force and ultimate tensile strength was associated with the onset of occlusal contact of the teeth. The organization of periodontal ligaments was improved after the teeth reached the occlusal level. After daily injections of HEBP for 3 days, there was a permanent reduction in root length and dento-alveolar ankylosis developed in the furcation area. CONCLUSION: (1) A single or three injections of HEBP changed the formation of acellular cementum to that of an atypical hyperplastic cementum which increased the resorption risk at this site. (2) The ultimate tensile strength was markedly reduced in teeth lacking acellular cementum.

Age Factors↗
PubMed1999

Cuspal deflection during polymerisation of composite lutes of ceramic inlays.

OBJECTIVE: The purpose of this study was to measure the cuspal deflection that occurs in teeth as a result of the dimensional changes of resin-based lutes during polymerisation. METHODS: Standardised MOD cavities were cut in 15 intact human premolar teeth using a custom paralleling device. A ceramic inlay was machined by the CEREC 2 system for each tooth ensuring an interface width of 50 microns (SD = 17.5) at the cavity margin. The 15 teeth were divided into three groups of five according to the cementation system employed: a microfilled hybrid posterior composite; a compomer restorative; a dual-cure luting composite. The inter-cuspal tooth dimension was recorded continuously with a laser micrometer assembly during a 2 min photoactivation period and a further 30 min post-activation period. RESULTS: A clear overall reduction in tooth dimension was detectable for the first 10 min of polymerisation. The mean changes ranged from -0.02% to -0.06% depending on the nature of the luting material. In addition, all samples exhibited a slight expansion of 0.03% during the time of light-activation. CONCLUSIONS: The dimensional changes that teeth experience during the polymerisation of resin-based lutes are clearly detectable. It can be postulated that an increase in the dimensions of the teeth during photoactivation occurs as a result of expansion of the lute due to the thermal energy delivered.

Analysis of Variance↗
PubMed2001

Evaluation of dental radiographic identification: an experimental study.

The object of this study was to assess the value of dental radiographs for the purposes of personal identification in the absence of tooth restorations. 198 periapical and bitewing radio graphs were taken of teeth contained in 22 dry skulls obtained from the skull collection of the Royal College of Surgeons of Edinburgh. Each selected view was taken three times: by a scientist, a dentist and a dental radiographer. Each operator independently positioned the films, selected the exposure times and positioned the cone of the X-ray machine. Three groups comprising forensic odontologists, dental vocational trainees and dental trainee hygienists attempted to match the randomly mixed radiographs into sets of three. Success rates for matching radio graphs ranged from 63.6 to 100%. The average for forensic odontologists was 93.3%, vocational trainees 85.2% and hygienists 89.7%. Where forensic odontologists had both formal training and experience, or extensive experience without formal training, the success rate was 100%. Where there was formal training but little experience the success rate was lower. Participants believed that root morphology and alignment had been the greatest aid to matching and not crown morphology. The depth of knowledge of the viewer correlated poorly with the number of correct results, although the forensic odontologists achieved the highest success rate. Formal training, although highly desirable, is no substitute for practical experience. Root morphology and alignment were cited most frequently as facilitating matching.

Clinical Competence↗
PubMed2001

Odontometrical method useful in determining gender and dental alignment.

Rao et al.'s method of sex determination, which considers the mandibular canine index (MCI) is one giving satisfactory results. However, they did not take occlusion into consideration. The aim of this study, therefore, was to evaluate the effectiveness of this method with respect to tooth alignment. The study population involved the students enrolled in the University of Nice-Sophia Antipolis. Two hundred and ten girls and 214 boys were randomly sampled (1/20). Both tooth sizes and dental arches were measured using a vernier calliper to calculate MCI for both sexes. The results were compared to standard MCI, taking into account tooth alignment.Rao et al.'s method can only be used in the case of correct lower-anterior dental alignment and by using the standard MCI of the local population.

Adult↗
PubMed2003

The accuracy of three methods of age estimation using radiographic measurements of developing teeth.

The accuracy of age estimation using three quantitative methods of developing permanent teeth was investigated. These were Mörnstad et al. [Scand. J. Dent. Res. 102 (1994) 137], Liversidge and Molleson [J. For. Sci. 44 (1999) 917] and Carels et al. [J. Biol. Bucc. 19 (1991) 297]. The sample consisted of 145 white Caucasian children (75 girls, 70 boys) aged between 8 and 13 years. Tooth length and apex width of mandibular canine, premolars and first and second molars were measured from orthopantomographs using a digitiser. These data were substituted into equations from the three methods and estimated age was calculated and compared to chronological age. Age was under-estimated in boys and girls using all the three methods; the mean difference between chronological and estimated ages for method I was -0.83 (standard deviation +/-0.96) years for boys and -0.67 (+/-0.76) years for girls; method II -0.79 (+/-0.93) and -0.63 (+/-0.92); method III -1.03 (+/-1.48) and -1.35 (+/-1.11) for boys and girls, respectively. Further analysis of age cohorts, found the most accurate method to be method I for the age group 8.00-8.99 years where age could be predicted to 0.14+/-0.44 years (boys) and 0.10+/-0.32 years (girls). Accuracy was greater for younger children compared to older children and this decreased with age.

Adolescent↗
PubMed2003

Sexual variation in bucco-lingual dimensions in Turkish dentition.

Sexual differences in the human skeleton have been well studied in many populations. Odontometric analysis of the human sexual variation has been less investigated and mostly derived from the dentition of extinct populations. Turkey is situated in a unique location where populations from different regions mixed with each other and created a rich gene pool. One might anticipate that modern Turkish population is composed of genes from the Balkans, Caucasus, Middle East, Iran and further as well as from ancient Romans, Byzantines, Arabs and Asiatic Turks. It is clear that contemporary Turks are a mixture of these extant and extinct people and ideal to consider it a representative study population. The purpose of this study is to analyze dental dimensions and sexual variation in living Turks and develop forensic techniques to identify human remains from the teeth when any other technique is not available or not reliable. The study is composed of Ankara University dental students (50 male and 50 female casts, average age of 21 years). Bucco-lingual breadths from 14 teeth (I1 through M2 of the maxilla and mandible) are taken from the left side and analyzed using the discriminant function statistics. An intraobserver error test did not indicate any statistically significant difference between any two measurements. Results of the study revealed that males exceeded females significantly (P<0.001) in dimensions. Coefficient of variation was most obvious in I1s and I2s of both jaws in both sexes. Stepwise discriminant function statistics suggested that upper C, and lower C and M2 are the most contributory teeth to the function. Additional formulae were calculated for situation in which only one or a fragmented jaw is available for identification. Overall accuracy of sex diagnosis ranged from 73 to 77%. In conclusion this research supports earlier studies that sexual dimorphism is population specific. While dental difference between the sexes in several human populations has been found highly dimorphic, it was not found so in Turks and accuracy of classification remained low at about 77%. The difficulty or the lack of dimorphism comes from male subjects.

Adult↗
PubMed1997

Logistic analysis of shovel and Carabelli's tooth traits in a Caucasoid population.

Caucasoid populations differ from Mongoloids by having a high prevalence of Carabelli's trait and a low prevalence of shovel trait. This study was conducted to investigate the association between the shovel and the Carabelli's traits in a Caucasoid population. The research design sought a Caucasoid population at Milwaukee of Wisconsin in United States. The Caucasoid group selected for study was the European descendant. The effects of sex and age on Carabelli's trait were controlled in this investigation, as was the association between tooth size and Carabelli's trait. Results show that males were more likely to have Carabelli's trait expressed on teeth than females. The buccolingual diameter of Carabelli's trait teeth was larger than that of teeth without the trait. After adjusting for sex, age, and tooth size, the existence of the shovel trait decreased the likelihood of having Carabelli's trait which shows an significant effect.

Asian People↗
PubMed2000

Interarch tooth size relationships of 3 populations: "does Bolton's analysis apply?".

This study evaluates whether Bolton's interarch ratios extend across populations and genders. The data were derived from systematically collected preorthodontic casts of 180 patients, including 30 males and 30 females from each of 3 populations (black, Hispanic, and white). Forty-eight mesiodistal contact points were digitized on each model, and the lengths of the anterior, posterior, and overall arch segments were calculated. The results showed significant (P <.05) ethnic group differences in all 6 arch segment lengths and in all 3 interarch ratios. Whites displayed the lowest overall ratio (92.3%), followed by Hispanics (93.1%), and blacks (93.4%). The group differences were due primarily to the relationships between the posterior segments. The arch segments of males were significantly larger than females; the overall and posterior ratios were also significantly larger in males than in females. Multiple regression analyses showed that individual differences in the overall ratio were most closely associated with the size of the lower second premolar, followed by the upper lateral incisors, upper second premolars, and the lower central incisors. In combination, these 4 teeth explained approximately 50% of the variation in the overall ratio between subjects. We conclude that interarch tooth size relationships are population and gender specific. Bolton ratios apply to white females only; the ratios should not be indiscriminately applied to white males, blacks, or Hispanics.

Adolescent↗
PubMed2000

The effect of tooth size discrepancy on occlusion: An experimental study.

The purposes of this experimental study are the following: (1) to compare the anterior and overall tooth size ratios reported by Bolton to values reported in epidemiologic studies, (2) to assess the accuracy of tooth size discrepancy measurements, (3) to investigate to what extent generalized tooth size discrepancy affects occlusion, (4) to investigate the effect of leveling the curve of Spee, and (5) to evaluate the effect of extraction therapy of 4 premolars on occlusion. For the first part of the study, Bolton's mean anterior and overall tooth size ratio (as well as the extraction values) were compared with calculations derived from 4 publications reporting mean mesiodistal tooth width by using the t test (P </=.05). The second part of the study was carried out on a setup made from 1 dental cast of a male patient judged to have an ideal occlusion at the end of a nonextraction treatment. Our data reveal (1) no significant difference between the overall tooth size ratios of the Bolton values compared to 4 studies, but the anterior ratios were significantly different, (2) high reproducibility (99%) of tooth size discrepancy measurements, (3) that severe tooth size discrepancy affects the occlusion only a little, (4) that an excessive (6 mm) curve of Spee creates the poorest setup result, and (5) that extraction therapy only slightly affected the final occlusion. The effect of generalized tooth size discrepancy appears to be limited.

Dental Occlusion↗
PubMed2000

Dental and facial skeletal characteristics and growth of males and females with class II, division 1 malocclusion between the ages of 10 and 14 (revisited)-part I: characteristics of size, form, and position.

The purpose of this study was to describe and analyze the craniofacial and dentofacial skeletal characteristics associated with Angle's Class II, Division 1 malocclusion. The material examined included 613 lateral head radiographs comprising 2 series: (1) 278 films of children with "normal" occlusion and (2) 335 films of children with Class II, Division 1 malocclusion. Each series was subdivided into 6 samples (3 female and 3 male; skeletal ages 10, 12, 14, [+/-6 months]), representing children with chronological ages ranging from 8.5 to 15.5 years. The radiographs were converted to computer-readable X and Y coordinate data and 52 linear, angular, and coordinate axis measurements were taken. Findings were visually verified by superimposing the computer-drawn composite plots of the Class II, Division 1 series over those of the normal series. In all 6 intergroup comparisons, it was found that: (1) the mandible and its dentition is similar to the controls in size, form, and position except for the position of the lower incisors in males; (2) the forehead (Gl), anteriorcranial base (Nas), maxilla (A) and dentition (molars and incisors) are protrusive (mesial positioned), with an increased frontal bone thickness at the level of the sinus, and a larger A-P maxilla, the palate of which is inclined superiorly at its anterior half; (3) no vertical dysplasia was evident; (4) the cranial base angle is larger, as are the anterior and posterior sections that compose it, but it is not related to mandibular position; (5) angular indexes of maxillary and mandibular position that included point Nasion are highly misleading indicators of maxillary and mandibular size and position. Visualized diagnosis via a composite norm based on age and sex might offer a more reliable alternative or supplement to the numeric reference standards now in use. Enlarged sinuses may contribute to the cause of Class II, Division 1 malocclusion.

Adolescent↗
PubMed2000

The use of the lingual arch in the mixed dentition to resolve incisor crowding.

In the mixed dentition, arch length preservation, maintaining the leeway space, can often provide adequate space to resolve lower incisor crowding. Yet the frequency of this occurrence is not known. To obtain this information, lingual arches were placed in the mandibular arches of 107 consecutive mixed dentition patients with incisor crowding to preserve arch length and make the leeway space available to resolve the crowding. Arch length decreased only 0.44 mm whereas the intercanine, interpremolar, and intermolar dimensions increased between 0.72 and 2.27 mm. There was adequate space to resolve the crowding in 65 (60%) of the 107 patients. If perfect arch length preservation had occurred, there would have been adequate space to resolve the crowding in 73 (68%) of the 107 patients. The correlation between leeway space and tooth size-arch size discrepancy was only 0.44.

Bicuspid↗
PubMed2003

Tooth size-arch length relationships in the deciduous dentition: a comparison between contemporary and historical samples.

In a recent study, it was reported that maxillary and mandibular arch lengths were significantly shorter in a sample of contemporary children in the deciduous dentition compared with a historical sample from about 50 years earlier. The purpose of this study was to describe secular changes that might have occurred in tooth sizes and tooth size-arch length relationships in the same cohorts of contemporary and historical North American white children in the deciduous dentition. The 2 samples were similar in terms of geographic location, racial and ethnic backgrounds, and socioeconomic status. Both samples were restricted to white children with a normal overjet (<4 mm) and a normal anteroposterior molar relationship, no anterior open bite, and no crossbite. In addition, subjects were excluded if any permanent teeth were erupted. Measurements of mesiodistal tooth sizes and arch lengths of maxillary and mandibular arches were made, and tooth size-arch length discrepancies (TSALD) were determined. The results indicated that tooth sizes were generally similar in the 2 cohorts but slightly larger in contemporary children. Crowding, as measured by TSALD, was found to be common in the mandibular arch for contemporary children in the deciduous dentition of both boys and girls. Moreover, crowding was much more common and severe in contemporary children compared with children in the historical cohort. Further research is needed to determine whether the increase in mandibular crowding in the deciduous dentition will continue to be observed in the mixed and permanent dentitions and to further establish these possible secular trends.

Cephalometry↗
PubMed2003

Comparison of measurements made on digital and plaster models.

Measuring plaster models by hand is the traditional method of assessing malocclusion. Recent technologic advances now allow the models to be digitized, measured with software tools, stored electronically, and retrieved with a computer. OrthoCAD (Cadent, Fairview, NJ) performs this service. The purpose of this study was to evaluate the reliability of the OrthoCAD system. Two independent examiners measured tooth size, overbite, and overjet on both digital and plaster models. The results were compared, and interexaminer reliability was assessed. The study sample consisted of 76 randomly selected pretreatment patients. The results showed a statistically significant difference between the 2 groups for tooth size and overbite, with the digital measurements smaller than the manual measurements. However, the magnitude of these differences ranged from 0.16 mm to 0.49 mm and can be considered clinically not relevant. No difference was found between the 2 groups in the measurement of overjet. Interexaminer reliability was consistent for both the plaster and the digital models.

Analysis of Variance↗
PubMed2003

Dynamic smile visualization and quantification: part 1. Evolution of the concept and dynamic records for smile capture.

The "art of the smile" lies in the clinician's ability to recognize the positive elements of beauty in each patient and to create a strategy to enhance the attributes that fall outside the parameters of the prevailing esthetic concept. New technologies have enhanced our ability to see our patients more dynamically and facilitated the quantification and communication of newer concepts of function and appearance. In a 2-part article, we present a comprehensive methodology for recording, assessing, and planning treatment of the smile in 4 dimensions. In part 1, we discuss the evolution of smile analysis and review the dynamic records needed. In part 2, we will review smile analysis and treatment strategies and present a brief case report.

Cephalometry↗
PubMed2003

Mixed dentition analysis in a Senegalese population: elaboration of prediction tables.

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Three main methods have been used to estimate the mesiodistal crown widths of unerupted canines and premolars: direct measurements on radiographs; calculations from prediction equations and tables; and a combination of radiographic measurements and prediction tables. Because there are clear racial differences in tooth sizes, the objectives of this study were to produce odontometric data, correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and the canine and premolars for each quadrant, and prediction tables with the regression equations, specifically for Senegalese children. Fifty black Senegalese students (25 women, 25 men, mean age 23.50 years) were selected from the University Cheikh Anta Diop in Dakar, Senegal. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary and mandibular canines and premolars were found to be 0.53 and 0.70, respectively. The standard error of the estimate was better (0.66) for women in the maxilla, and the r(2) values ranged from 0.46 to 0.57 for both sexes. Prediction tables were prepared. The accuracy of the prediction tables should be tested in a larger sample including more ethnic groups.

Adult↗
PubMed2003

Transverse molar movements during growth.

The purpose of this study was to evaluate changes in molar crown torque and intermolar arch width from the time of permanent first molar eruption to early adulthood. Molar crown torque and intermolar arch width were measured in 36 untreated subjects with Class I occlusion from the Iowa Facial Growth Study at approximate ages 7.5, 10.3, 12.9, 16.5, and 26.4 years. On average, the mandibular first and second molars uprighted buccally by 5.0 degrees and 7.5 degrees, respectively. Mandibular first and second molar intermolar width increased by 2.2 and 0.78 mm, respectively. On average, maxillary first and second molars uprighted lingually by 3.3 degrees and 5.9 degrees, respectively. Maxillary first and second intermolar width increased by 2.8 and 2.0 mm, respectively. Results of statistical analysis by the Wilcoxon signed rank test indicate that (1) maxillary molars erupt with buccal crown torque and upright with age, whereas mandibular molars erupt with lingual crown torque and upright with age (P <.01), and (2) molar crown torque changes are accompanied by concurrent increases in maxillary and mandibular intermolar width (P <.01).

Adolescent↗