Tooth abrasion in unilateral posterior crossbite in the deciduous dentition

The aim of this study was to evaluate the degree of abrasion in posterior teeth of subjects with unilateral posterior crossbite in the deciduous dentition. A group of 54 untreated subjects in deciduous dentition (test group, TG) was selected from a parent sample of 1500 patients from the files of the Department of Orthodontics of the University of Florence. A sample of 20 subjects with normal occlusion in the deciduous dentition was selected as the control group (CG). As experimental units in TG, 54 crossbite sides (CB, consisting of 33 right and 21 left crossbite sides) and 54 noncrossbite sides (NCB) were used. In CG, one randomly chosen single side for each subject (NCBC) was used for comparisons. The findings of the present study indicated that subjects with unilateral crossbite in the deciduous dentition showed a significantly smaller degree of dental abrasion in the crossbite side when compared with both the opposite side and control group sides. The lack of abrasion in crossbite sides was primarily due to a significantly lesser degree of abrasion of the upper deciduous canines.     

Severity, distribution, and correlates of occlusal tooth wear in a sample of Mexican-American and European-American adults

PURPOSE: The objective of this study was to determine the severity, distribution, and correlates of tooth wear in a sample of Mexican-American and European-American adults drawn from a community-based longitudinal aging study on oral health. MATERIALS AND METHODS: The maxillary teeth of 71 subjects enrolled in a longitudinal aging study were assessed using a previously introduced five-point (0 to 4) ordinal scoring system in which each tooth is given a score describing the severity of wear. The tooth wear scores were compared with data concerning demographic factors, functional/parafunctional habits, soft drink consumption, and bite force measurements to determine specific correlates of tooth wear. RESULTS: The mean wear score for all teeth was 1.50 on the five-point scale. There was a significant difference between the mean wear score of anterior teeth (1.85) and posterior teeth (1.17). Bivariate analyses detected a moderate degree of correlation between maxillary tooth wear and age and bite force. Maxillary tooth wear was significantly greater in males and in subjects with reported teeth clenching/grinding. Multivariate analyses revealed that age, gender, bite force, self-reported teeth clenching/grinding, and number of daily meals/snacks had significant correlations with maxillary tooth wear. CONCLUSION: The overall severity of maxillary tooth wear in this sample of Mexican-American and European-American adults was low, with anterior teeth having a greater degree of wear than posterior teeth. Age, gender, bite force, teeth clenching/grinding, and number of daily meals/snacks are potential factors that may have contributed to tooth wear in the study sample.     

Difference in dental lateral arch length between 9-year-olds born in the 1960s and the 1980s

This study was carried out in two cohorts of 9-year-olds, born in the 1960s and the 1980s in Sweden and Norway, to test the hypothesis that there has been a change in the lateral arch space conditions of the dentition during the last decades. In Norway, 61 children born in 1963 and 58 children born in 1983 were examined. In Sweden, 66 children born in 1961 and 67 children born in 1984 were examined. Children with a prolonged sucking habit, major dentofacial anomalies, history of orthodontic treatment, and ancestors of foreign origin were excluded to avoid influence of these factors on the development of the dentition. Linear measurements were performed between the mesial surface of the first permanent molars and the distal surface of the permanent lateral incisors in the maxillary and mandibular dental arches with use of a sliding caliper. The results showed that the children born in the 1980s had significantly larger lateral arch spaces in the maxillary dental arch (P <.05) and in the mandibular dental arch (P <.01) than did the children born in the 1960s. The amount of tissue loss in the second deciduous molars (the teeth having caries lesions or having been extracted) was greater in the 1960s groups than in the 1980s groups (P <.001). Thus, the hypothesis, that there has been a change in the lateral arch space conditions during the last decades, was confirmed. The most obvious reason is the decline in caries prevalence that has occurred in the same period; thus, there has been less loss of proximal tooth material of posterior teeth.     

Tooth wear patterns in the deciduous dentition

Tooth wear is common in the deciduous dentition. A recent study suggests that tooth wear in the deciduous dentition is related to subsequent tooth wear in adults, so that early identification of factors related to tooth wear could be of long-term benefit. The purposes of this study were to describe patterns of tooth wear in the deciduous dentition and to relate tooth wear to occlusal characteristics and longitudinal dietary patterns. Data were collected as part of a longitudinal study of a cohort of children recruited at birth from Iowa hospitals. Stone casts were obtained in the deciduous dentition stage, and 355 children, 4 to 5 years old, met the selection criteria. Tooth wear was categorized for each tooth as none, mild, moderate, or severe, and related to occlusal characteristics and longitudinal data on fruit juice and soft drink consumption. All children exhibited some tooth wear on at least 1 tooth, and nearly 16% of them had at least 1 tooth with severe wear. Tooth wear was generally more severe in the maxillary arch and the anterior teeth. Severe tooth wear on the molars was significantly related to posterior crossbites, but severe tooth wear on the incisors was related to Class III canine relationships. There were no statistically significant relationships between tooth wear and soft drink or fruit juice consumption. Based on our results, we concluded that mild tooth wear is universal in the deciduous dentition, but only a few occlusal factors are related to severe tooth wear. Tooth wear was not related to any dietary patterns we investigated.     

Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

Summary  The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors ( P  = 0·7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different ( P  < 0·0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.     

The potential of deciduous and permanent bovine enamel as substitute for deciduous and permanent human enamel: Erosion-abrasion experiments

Aim of the present study was to compare toothbrushing abrasion of eroded human and bovine enamel utilizing a toothpaste slurry. The surfaces of each 36 teeth from cattle and calves and from each 36 human wisdom teeth and deciduous teeth were polished. Each 12 specimens from the respective tooth type were used for assessing toothbrushing abrasion only (A), erosion only (E) and the combination of erosion and toothbrushing abrasion (EA). The EA samples were subjected to 20 cycles comprising a demineralization/remineralization procedure directly followed by toothbrushing abrasion (100 strokes, 300 g load, toothpaste slurry: 3 ml artificial saliva mixed with 1g dentifrice). Demineralization in form of erosion was performed with 1% citric acid (1 min), remineralization with artificial saliva (15 min). Between the cycles, the samples were stored in artificial saliva. Wear of the treated surfaces with reference to untreated areas was determined profilometrically. The samples subjected to abrasion only (A) did not show a significantly different wear between the different kinds of teeth. The comparisons of substance loss between teeth of different species revealed that hard tissue loss of the human deciduous teeth was significantly lower as compared to calves' teeth after both erosion and erosion-abrasion. Also, both erosion only and erosion-abrasion caused higher enamel loss in cattle's teeth than in human wisdom teeth. It is concluded that human eroded enamel offers better resistance against brushing than bovine enamel.     

牙齿重度磨损的相关临床特征分析

目的探讨牙列重度磨损患者的相关临床特征。方法选择牙列重度磨损患者137例,收集其相关临床信息,利用其研究模进行磨损指数评价,应用两独立样本非参数检验进行数据分析。结果 45岁以上组患者的前牙、前磨牙、磨牙磨损指数均显著高于45岁以下组（P〈0.01）。男性患者的前牙、前磨牙、磨牙磨损指数均显著高于女性患者（P〈0.01）。有磨牙症史患者的前牙、前磨牙、磨牙区的磨损指数高于无磨牙症史患者（P〈0.01）。结论重度磨损患者的牙齿磨损程度与年龄、性别及有无磨牙症史关系密切。     

Tooth surface loss: does recreational drug use contribute?

OBJECTIVE: This pilot study was designed to measure tooth wear in a sample of 13 subjects who regularly use amphetamine-like drugs (Ecstasy, amphetamines) and compare the observed wear with a matched sample of nondrug users. DESIGN: The two groups, both composed of 13 undergraduate students, were matched for age and sex. Other factors influencing tooth wear were controlled by matching the groups on their responses to a questionnaire asking about recognised common causes of tooth wear. The participants teeth were examined and the degree of wear scored according to a tooth wear index. RESULTS: Severity of occlusal tooth wear of the lower first molar teeth was significantly greater in the drug user group than in the control group (P<0.05). No other statistically significant differences between the groups were found. CONCLUSION: Regular use of amphetamine-like drugs could be associated with increased posterior tooth wear.     

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.     

Strontium-90 in Deciduous Teeth Collected in Northern Finland from Children Born in 1952–1964.

Strontium-90 content was measured by means of Cerenkov radiation in deciduous teeth collected in three areas in northern Finland from children bom in 1952–1964.

The ⁹⁰Sr levels in tooth crowns in areas I and II showed a continuous increase in children born in 1952–1958, no further increase during the years 1959–1961, a sharp increase in 1962–1963, and no further change in 1964. In the northernmost part of Finland (area III) the strontium-90 contents of deciduous teeth when plotted against year of birth showed a slightly different trend with no increase during the years 1952–1957 and a steep rise in 1958 and 1959. These changes occurred in both Lapp and non-Lapp children. These differences in the strontium-90 content of deciduous teeth were presumably related to environmental peculiarities and specific dietary habits in area III. The maximum strontium-90 level, 16.76 pCi/gCa, was found in a sample of tooth roots of four Skolt children born in 1963.

The strontium-90 contents in the crowns of the four types of deciduous teeth were related as follows: second molars > cuspids > first molars > incisors.     

Secular changes in tooth size and dental arch dimensions in the mixed dentition

Secular changes in the mixed dentition were studied. Permanent tooth size and dental arch dimensions were examined in Norwegian children born in the 1960s and 1980s, Swedish children born in the 1960s and 1980s, Norwegian Sami children born in the 1980s, and a sample of Norwegian skulls dating from the 14th to the 19th century. The Norwegian Sami children were nomadic in the summertime. A sample of pigs was studied before and after a maceration process to determine what dimensional changes might occur in such a process. A shrinkage of 0.3%-1.7% was found. This information was used when the skulls were compared with the modern groups. Lateral dental arch lengths were shorter in the children born in the 1960s compared with the children born in the 1980s. This was a result of the higher prevalence of caries in the second deciduous molars in the 1960s groups. Children who had lost a deciduous canine prematurely were found to have smaller dental arch perimeters. When compared with other data, this was blamed on a pre-existing crowding. Permanent tooth size was smaller in the skulls compared with the modern groups. Improved nutrition is considered to be the main reason for the difference. Relative dental arch space differed in the group born in the 1960s from that in the other groups, indicating a greater prevalence of crowding in the former. Relative dental arch space in the skulls and in the group born in the 1980s was similar. A more traditional way of living, as practised by the Sami group in this thesis, was not favorable for relative dental arch space. The transverse intermaxillary relation in boys changed from the 1960s to the 1980s, which indicated that the 1980s group ran a greater risk of developing a posterior cross-bite. Before the same conclusion could be made in the girls, the mesial drift of the first permanent molars had to be corrected for, because of a higher prevalence of caries in the 1960s group. The sex-pooled analysis of the skulls and the contemporary groups revealed that the risk for developing a posterior cross-bite in the 1980s group was greater than in the skulls. The skulls had smaller arch depths than the modern groups.     

A cohort study on prevalence of dental caries concerning primary schoolchildren in one village of Niigata Prefecture

To review the previous preventive measures against the incidence of dental caries in children, we started to examine the state of dental health in children at the age of 18 months. The annual dental examination continued up to 12 years of age (sixgraders). Enrolled in this study were a total of 225 children living in a Town T and born between 1980 and 1982. Meanwhile, we made surveys in order to gauge the degree to which the subjects and their parents have concern for oral health. The findings and their relationships to the caries incidence were analyzed using an epidemiological technique. The annual dental examinations revealed that in primary dentition the incidence of caries tends to increase in 3-year-olds while in permanent dentition the carious process extends in 4–6 graders. By kind of teeth, primary molars accounted for 52% of the affected deciduous teeth. First molars made up 72% of all the decayed permanent teeth. Using the two caries cumulative indexes developed by our department for recording the prevalence and severity of tooth decay in the deciduous dentition and in the permanent dentition, respectively, we found that there is a correlation between the incidence of caries in the deciduous dentition and that in the permanent teeth. The two formulae are based on the cumulative number of decayed teeth that appeared in the deciduous dentition and permanent dentition for a given period of time. In order to find whether there is any correlation between caries attack and attention paid to the risk factors, we divided the subjects into two groups by the number of decayed teeth per person. In the group made up of those with many carious teeth, it was noted that between-meal snacks are most likely to produce caries in deciduous teeth, while lifestyle affects permanentteth.

     

Wear of two denture teeth materials in vivo—2-year results

Objective

(1) To quantify wear of two different denture tooth materials in vivo with two study designs, (2) to relate tooth variables to vertical loss.

Methods

Two different denture tooth materials had been used (experimental material = test; DCL = control). In study 1 (split-mouth, 6 test centers) 60 subjects received complete dentures, in study 2 (two-arm, 1 test center) 29 subjects. In study 1 the mandibular dentures were supported by implants in 33% of the subjects, in study 2 only in 3% of the subjects. Impressions of the dentures were taken and poured with improved stone at baseline and after 6, 12, 18 and 24 months. Each operator evaluated the wear subjectively. Wear analysis was carried out with a laser scanning device. Maximal vertical loss of the attrition zones was calculated for each tooth cusp and tooth. A mixed linear model was used to statistically analyse the logarithmically transformed wear data.

Results

Due to drop-outs and unmatchable casts, only 47 subjects of study 1 and 14 of study 2 completed the 2-year recall. Overall, 75% of all teeth present could be analysed. There was no statistically difference in the overall wear between the test and control material for either study 1 or study 2. The relative increase in wear over time was similar in both study designs. However, a strong subject effect and center effect were observed. The fixed factors included in the model (time, tooth, center, etc.) accounted for 43% of the variability, whereas the random subject effect accounted for another 30% of the variability, leaving about 28% of unexplained variability. More wear was consistently recorded in the maxillary teeth compared to the mandibular teeth and in the first molar teeth compared to the premolar teeth and the second molars. Likewise, the supporting cusps showed more wear than the non-supporting cusps. The amount of wear did not depend on whether or not the lower dentures were supported by implants. The subjective wear was correct in about 67% of the cases if it is postulated that a wear difference of 100 μm should be subjectively detectable.

Significance

The clinical wear of denture teeth is highly variable with a strong patient effect. More wear can be expected in maxillary denture teeth compared to mandibular teeth, first molars compared to premolars and supported cusps compared to non-supported cusps.Laboratory data on the wear of denture tooth materials may not be confirmed in well-structured clinical trials probably due to the large inter-individual variability.     

Cross-sectional study of orthodontic treatment and missing of permanent teeth in two birth cohorts of Finnish students according to sex

Abstract Undergraduate students (n= 451) at a Finnish university were studied. For analysis, the subjects were divided into two birth cohorts: those born before 1955, and those born in that year or later. Information about previous orthodontic appliance therapy was obtained from the students by using a structured questionnaire. Missing permanent teeth (second and third molars excluded) were recorded at a dental examination. Every 10th student had received orthodontic treatment; the proportion of orthodontically treated subjects was higher for females (14%) than for males (5%). Seven percent of students born in 1954 or earlier and 15% of the younger students had had orthodontic treatment before 1977. In 39% of subjects, at least one permanent tooth was missing while only 12% had lost more than two permanent teeth. The tooth missing most often was the permanent mandibular first molar (in 23 % of subjects). Frequency of tooth loss was the same in males and females. At least one permanent tooth was missing in 48% of the older and in 31 % of the younger students. At least one first molar had been lost by 36 % of the older students and 20% of the younger ones. Fewer first molars but more permanent teeth anterior to the first molars were missing in subjects who had had orthodontic, treatment than in subjects who had not had such treatment. Among Finnish students the frequency of extractions of permanent teeth because of caries is decreasing, and the frequency of orthodontic treatment is increasing. Females are more likely to seek orthodontic treatment than males are.     

Laboratory wear investigation of resin posterior denture teeth.

This investigation compared the wear resistance of three "improved" resin posterior denture tooth formulations with two conventional products on a mechanical toothbrush abrasion machine. The ability of the teeth to resist this type of abrasion was evaluated by determination of the weight loss during 339 hours of brushing with firm nylon bristle toothbrushes. All brands exhibited negligible loss, with the conventional brands performing better than the "improved" formulations.     

一种新的牙齿记录法

目的:介绍一种新的牙齿记录法,以达到简便而准确地描述和记录牙齿的目的。方法:T或t作为记录牙齿的标识字符,T代表恒牙,t代表乳牙。用数字1～8和1～5从牙弓中线向远端对恒牙和乳牙编号。用"字母加数字"的方式对恒牙和乳牙、上颌牙和下颌牙、前牙和后牙以及牙位进行记录。结果:恒牙标记为T1～T8,乳牙标记为t1～t5。上、下颌恒牙分别标记为UT1～UT8和LT1～LT8。上、下颌乳牙分别标记为Ut1～Ut5和Lt1～Lt5。前牙、前磨牙和磨牙分别标记为T(1-3)、T(4、5)和T(6-8)。乳前牙和后牙分别标记为t(1-3)和t(4、5)。恒牙牙位用上下标牙位记录法或"UR、UL、LR、LL"加"T1～T8"标记。乳牙牙位用上下标牙位记录法或"UR、UL、LR、LL"加"t1～t5"标记。结论:新的牙齿记录法能简便而准确地标记牙齿、上下颌牙齿、前牙和后牙以及牙位。     

老年恒牙、年轻恒牙及乳牙釉质磨损性能的体外对比研究

目的探讨并比较各个年龄组人牙釉质磨损行为的异同.方法采用老年恒牙、年轻恒牙及乳牙各8个釉质样本,经体外模拟摩擦试验测得其磨损量,通过测量硬度和断裂韧性以及分析磨斑形貌和釉质中Ca、P、Si元素含量等揭示釉质的摩擦磨损机制.结果老年恒牙、年轻恒牙、乳牙牙釉质磨损量分别为(2.40±1.10)×10-12 m3、(3.50±1.83)×10-12 m3、(4.86±2.49)×10-12 m3,其中老年恒牙磨损明显小于乳牙(P＜0.05),年轻恒牙与乳牙、老年恒牙与年轻恒牙磨损量间差异无显著性(P＞0.05),但三者在机械性能和磨损特征方面均有所不同.结论各年龄组人牙釉质与陶瓷牙对摩时,主要发生磨粒磨损和断裂磨损,各类牙釉质超微结构的差异决定了其抗磨性能的不同.人牙釉质的硬度和断裂韧性测量值与磨损量无对应关系.     

Craniofacial growth changes and dental attrition in the primary dentition

Presence of pronounced incisal and occlusal wear in primary dentition is fairly common in children. Several factors are implied, however, the possible correlation of craniofacial growth to the occurrence of severe incisal tooth wear in children has not been described to date. Thus, this study was aimed to find any association between the craniofacial growth changes and the occurrence of severe incisal wear in children.Materials and methodsTwenty-seven sets of series of dental casts and corresponding lateral cephalograms are selected from the archive of Pediatric Dentistry, Department of Tokyo Medical and Dental University Hospital. Samples were divided into two groups based on the extent of incisal wear observed on the primary maxillary anterior teeth: slight attrition (N = 13) and severe attrition (n = 14) groups. Lateral cephalograms at early deciduous dentition at T1 (3.5 ± 0.6 years old) and late deciduous dentition at T2 (6.2 ± 0.6 years old) were manually traced and 17 linear and 22 angular measurements were measured with analyzing software (WinCeph ver.9). Annual growth rate for each sample was calculated to determine any significant difference between samples from two groups.ResultsSignificant horizontal growth of the mandible with both the reduction of anterior tooth height and increase of posterior tooth height were found in the severe attrition group. Reduction of upper incisor angle to FH plane and upper dental arch length were also related with the attrition of teeth.ConclusionsThe incisal tooth wear of deciduous teeth was significantly associated with the craniofacial growth changes.     

Molar tooth attrition in a selected group of Nigerians

ABSTRACT A study of the degree and gradient of attrition was undertaken on 352 molar teeth of 88 selected Nigerian subjects. A method for the quantification of attrition experience per molar tooth is described. There is a close correlation between age and the degree of attrition of the first molar. This finding may be of value in age determination in forensic odontology. The wear on the first molar is about two stages ahead of that on the second and third molars. It is suggested that the degree of tooth attrition may be an index of masticatory activity.     

The Use of Custom‐Milled Zirconia Teeth to Address Tooth Abrasion in Complete Dentures: A Clinical Report

A patient exhibited severe abrasion of resin posterior denture teeth including perforation of the denture base. New dentures were provided to explore the application of zirconia teeth for complete dentures. [Correction added to online publication 07 November 2012: “Zirconium” corrected to “Zirconia”.] Traditional denture procedures were combined with fixed prosthodontic CAD/CAM procedures to fabricate custom‐designed four‐tooth posterior segments in hollow crown form to reduce weight and with a retentive form for interlocking to the denture base. The new dentures were successful in reducing wear of the denture teeth over the short‐term follow‐up period.