Long-term effects of Class II orthodontic treatment on oral health.

AIM: To investigate the long-term (≥15 years) benefit of orthodontic Class II treatment (Tx) on oral health (OH). SUBJECTS AND METHODS: All patients (Department of Orthodontics, University of Giessen, Giessen, Germany) who underwent Class II correction (Herbst-multibracket Tx, end of active Tx ≥ 15 years ago) and agreed to participate in a recall (clinical examination, interview, impressions, and photographs) were included. Records after active Tx were used to assess the long-term OH effects. Data were compared to corresponding population-representative age-cohorts as well as to untreated Class I controls without orthodontic Tx need during adolescence. RESULTS: Of 152 treated Class II patients, 75 could be located and agreed to participate at 33.7 ± 3.0 years of age (pre-Tx age: 14.0 ± 2.7 years). The majority (70.8%) were fully satisfied with their teeth and with their masticatory system. The Decayed, Missing, Filled Teeth Index (DMFT) was 7.1 ± 4.8 and, thus, almost identical to that of the untreated Class I controls (7.9 ± 3.6). In contrast, the DMFT in the population-representative age-cohort was 56% higher. The determined mean Community Periodontal Index (CPI) maximum score (1.6 ± 0.6) was also comparable to the untreated Class I controls (1.7 ± 0.9) but in the corresponding population-representative age-cohort it was 19-44% higher. The extent of lower incisor gingival recessions did not differ significantly between the treated Class II participants and the untreated Class I controls (0.1 ± 0.2 vs. 0.0 ± 0.1 mm). CONCLUSION: Patients with orthodontically treated severe Class II malocclusions had a lower risk for oral health impairment than the general population. The risk corresponded to that of untreated Class I controls (without orthodontic Tx need during adolescence).

Assessment of the progression of tooth wear on dental casts.

Many methods are available for the grading of tooth wear, but their ability to assess the progression of wear over time has not been studied frequently. The aim was to assess whether the occlusal/incisal grading scale of the Tooth Wear Evaluation System (TWES) was sensitive enough for the detection of tooth wear progression from 14 to 23 years of age. A total of 120 sets of dental casts were gathered from 40 people, of whom impressions were made at 14, 18 and 23 years. The TWES was used to assess loss of clinical crown height throughout the entire dentition. There was a significant difference in the TWES scores between the three age groups on all teeth (Friedman tests; P < 0.005 in all cases). Post hoc Wilcoxon tests revealed that the difference between the scores between 14 and 18 years and between 18 and 23 was significant for most teeth. It was concluded that the TWES is sensitive enough to detect changes in tooth wear over time.

Reliability of cranial base measurements on lateral skull radiographs.

OBJECTIVE: To explore the reliability of identification of anatomic landmarks on lateral skull radiographs of young unaffected individuals that has conventionally been used to diagnose pathologic relationships in the craniovertebral junction. MATERIAL AND METHODS: From the Helsinki longitudinal growth study, 20 randomly selected lateral radiographs were analyzed and re-analyzed by two examiners. Both located seven cephalometric landmarks based on which five measurements were calculated. The differences of results were compared. With similar method three radiographs were analysed by 11 examiners and results were compared. RESULTS: Some anatomic landmarks were easier to locate than others on lateral skull radiographs leading to differences in measurements based on them. We found the magnitude of the difference to be dependent on the landmark serving as reference. Inter- and intra-examiner errors were of similar magnitude, although intra-examiner error declined in the repeated landmark identification. Variation in a single landmark location had in general little effect on the measurement value. CONCLUSION: Variations in landmark location lead to differences in numeric evaluation of the anatomic relationships in the skull base area. These differences were, however, shown to have little clinical significance. Hence, the documented methods are applicable for screening of basilar pathology.

Root-crown ratios of permanent teeth in a healthy Finnish population assessed from panoramic radiographs.

An unfavourable root-crown (R/C) ratio caused by short dental roots may result from a developmental deficiency, root resorption after orthodontic treatment, or dental trauma. In the assessment of root shortening, subjective grading has often been used. For objective tooth measurements, varying materials and methods may make the results impossible to compare. This study used a simple, objective method to assess the R/C ratio (relative root length) of mature permanent teeth from panoramic radiographs (PRGs), tested its reproducibility and calculated the mean values of R/C ratios and their variations in a healthy Caucasian (Finnish) population. Two thousand seven hundred and seventy-nine teeth were measured on 108 PRGs. The intra- and inter-examiner reproducibility of the assessment method was good (Pearson correlation coefficients 0.87 and 0.83, respectively; P < 0.001) and the mean R/C ratios did not differ between the repeated measurements (P > 0.05). The biological variance in all cases exceeded the error variance for each tooth. These facts suggest that the method reported in this study can be used in the assessment of the relative root length of 'normal' teeth and its alterations in teeth with developmental or acquired aberrations of dental roots. Males, overall, tended to have higher R/C ratios than females; P-values varied from non-significant to less than 0.01. With the exception of the permanent lateral incisors in males and the permanent second molars in both genders, the ratios of the antagonist teeth were significantly greater in the mandible than in the maxilla (P < 0.05 for the lateral incisors of females; P < 0.001 for all other teeth). Consequently, in quantifying root shortening in developmentally short-rooted teeth, tooth- and gender-specific reference values should be employed. The Finnish R/C data reported here for all teeth except third molars could be used for comparison with other populations, patient groups or individuals where crown-root aberrations are suspected.

Emergence of permanent teeth and dental age in a series of Finns.

The emergence of permanent teeth was studied in 187 Finnish children who had longitudinal records of the emergence of all permanent teeth except third molars. Exact emergence dates were known for about one third of the teeth. Emergence ages of the remaining teeth were based on their presence and absence at clinical examinations. We calculated ages at clinical eruption of permanent teeth and tooth counts at half year intervals. Ages corresponding to counts of permanent teeth from 1 to 27 are also given. The schedules presented, which slow means, standard deviations, and percentage distributions, are expected to serve as useful references in clinical dentistry, pediatrics, forensics, and research. The mandibular central incisor emerged before the first molar of the same jaw in 68% of the children. A change in the emergence order of these teeth in Finns seems to have occurred in the 1960s. A visual comparison of dental maturity curves based on tooth counts with curves based on tooth mineralization in a previous Finnish radiographic study showed that the mean curves had roughly the same form, whereas the forms of standard deviation curves differed distinctly. It appears that the two methods to assess dental maturity are not interchangeable in practice. Tooth counts can be used in maturity estimations up to about 13 years of age, whereas the radiographic method works best to about 11 years.

Age estimation in small children: reference values based on counts of deciduous teeth in Finns.

The eruption of teeth in the mouth is suitable for age estimations during the period when teeth are actively emerging, in the deciduous dentition phase approximately from the age of 6 months to 2.5 years. Estimations of age can be performed simply by counting the number of teeth in the mouth. Reliability of the estimates depends on the reference data available and each population group should preferably have its own standards. In the present study timing of eruption of successive deciduous teeth was studied longitudinally in 129 Finns. The dates of clinical eruption of deciduous teeth were recorded by mothers and checked by dentists. In 40 of the 129 children emergence ages of at the most the four last teeth were based only on semiannual registrations performed by dentists. The main purpose was to provide normal timetables of tooth eruption in small children in forms that are practical in estimations of dental age. No sexual dimorphism existed in the timing of clinical eruption of successive deciduous teeth. The mean age corresponding to the presence of one tooth in the mouth was 7.1 months (S.D.=1.78) and that corresponding to tooth count 19 was 27.8 months (S.D.=3.99). If the chronological age is known, the presented distributions and means with variations make it possible to estimate the degree of advancement or delay in a child's dental development. If the age of the child is not known, the mean and median ages can be used for estimations of chronological age. However, estimations of age should not be based only on tooth counts because of marked variation also within this homogeneous group.

Development of horizontal tooth wear in maxillary anterior teeth from five to 18 years of age.

Sizes of horizontal wear facets of maxillary anterior teeth were studied longitudinally from the primary dentition at age five to the young adult dentition at the age of 18 years. By a planimetric method, we calculated the wear areas on dental casts taken at the ages of five, ten, 14, and 18 years from the dentition of 39 healthy, orthodontically untreated subjects with good morphological occlusion. For young adults, we also studied the association between the amount of wear and reported parafunctions, maximal bite force, salivary buffer capacity, salivary flow rate, and some cephalometric variables. Size of wear facets on all anterior teeth increased with age. Significant correlations were found between the total wear areas of the six anterior primary teeth at five years of age and those of their permanent successors at age 14 (r = 0.44) and 18 (r = 0.39). For an individual, tooth wear at five years of age was, however, of low predictive value for tooth wear in young adulthood, whereas tooth wear at 14 years of age predicted it well (r = 0.89). Highest correlations between tooth wear and background factors at 18 years of age were found for maximal anterior bite force (r = 0.44) and for the size of the gonial angle (r = -0.31). Wear of anterior teeth was not associated with reported parafunctions in young adulthood.

Salivary caries-related tests as predictors of future caries increment in teenagers. A three-year longitudinal study.

The aim of the study was to evaluate the capability of caries-related salivary tests and a test based on past caries experience (baseline DFS) to select persons at high risk for caries. The subjects (n = 122) were 12-17 years old at the beginning of the study. Caries was registered and salivary samples were taken annually during the 3-study period. The 3-year caries increment was positively correlated to the baseline DFS (r = 0.46, p less than 0.001), salivary level of mutans streptococci (r = 0.30, p less than 0.001) and lactobacilli (r = 0.30, p less than 0.001), and combined level of mutans streptococci and lactobacilli (r = 0.39, p less than 0.001) and negatively correlated to the buffering capacity of saliva (r = -0.22, p less than 0.05). Tests based on either past caries experience or mutans streptococci or lactobacilli levels alone were not efficient in selecting persons at high risk for caries. Among the tests, DFS was the most sensitive and specific. A combination of either microbial test and DFS was more efficient to select persons at risk than various alternatives alone. The sensitivity was 84% and the specificity 62% for the combination of lactobacilli test and DFS and 71% and 79% respectively for the combination of mutans streptococci and DFS. In the former combination the positive prediction value was 43% and in the latter 56%.

Signs and symptoms of craniomandibular disorders in a series of Finnish children.

The prevalences of subjective symptoms and clinical signs of craniomandibular (CM) disorders, orofacial parafunctions, and occlusal conditions were determined in a series of Finnish children (n = 166). All were first interviewed, and then 156 of them were examined clinically. Fifty-two per cent of the children reported at least one subjective symptom, and 75% at least one parafunctional habit. Clinical signs were common but rarely severe in accordance with Helkimo's clinical dysfunction index (Di). Both the number of subjective symptoms (p less than 0.001) and the number of orofacial parafunctions (p less than 0.05) correlated with the clinical dysfunction index.

Dental maturity in Finnish children, estimated from the development of seven permanent mandibular teeth.

Overall dental maturity was studied semilongitudinally in a group of 248 healthy children born in Helsinki in 1968-73. In all, 738 orthopantomograms were taken of these children at ages of 2.5-16.5 years. Overall dental maturity was estimated by the method of Demirjian and Goldstein, which is based on the development of seven left mandibular permanent teeth. The aim of the study was to construct dental maturity curves for Finnish children and to compare their dental maturity with that of French-Canadian children studied by the same method. The Finnish children were more advanced in dental maturation than French-Canadian children (p less than 0.01). In boys the advancement was seen at the age of 5-10 years and in girls at the age of 4-12 years. These findings suggest differences in overall dental maturity among white population groups.