Dentoskeletal and soft tissue changes after treatment of crowding with premolar extractions: a 50-year follow-up.

BACKGROUND: The long-term effects on dentofacial morphology of interceptive treatment with premolar extractions, in the absence of subsequent orthodontic treatment, have not been fully explored. OBJECTIVE: The aim was to investigate the effects of premolar extractions (without subsequent orthodontic treatment) on the dentoskeletal and soft tissue profile of patients aged between 12 and 62 years with Class I malocclusion with severe crowding, as compared to untreated controls. MATERIALS AND METHODS: The Extraction group (N = 30 with Class I crowding malocclusion) had their first premolars removed in early adolescence without subsequent orthodontic treatment. The Control group included 30 untreated subjects with Class I normal occlusion. Cephalograms were taken at 12 (T1), 15 (T2), 30 (T3), and 62 (T4) years of age. A superimposition-based cephalometric method was used to assess the dentoskeletal and soft tissue changes. RESULTS: There were no significant differences between the Extraction and Control groups in terms of skeletal sagittal relation, incisor inclination, and protrusion, or most of the soft tissue parameters throughout the observation period. However, significant differences were observed between the groups with respect to the vertical relations in T2-T3, such that the Extraction group showed more-pronounced decreases in the ML/NSL, ML/NL, and Gonial angles and more-pronounced increases in facial heights. CONCLUSIONS AND IMPLICATIONS: Treatment for subjects with Class I malocclusion with severe crowding by the extraction of four premolars, without subsequent orthodontic treatment, does not affect the long-term dentoskeletal and soft tissue profile, as compared to an untreated Control group. The degree of crowding, rather than changes in dentofacial morphology, is crucial in deciding on extraction therapy.

Craniofacial changes from 13 to 62 years of age.

BACKGROUND: In long-term studies of orthodontic, orthognathic, and prosthodontic treatments, control subjects are needed for comparison. OBJECTIVES: To study the craniofacial (skeletal, soft tissue, and dental) changes that occur in untreated subjects with normal occlusion between 13 and 62 years of age. MATERIALS/METHODS: Thirty subjects with a Class I normal occlusion and harmonious facial profile were studied. X-ray examinations were performed at 13 (T1), 16 (T2), 31 (T3), and 62 (T4) years of age, and data were obtained from cephalograms. In total, 53 angular and linear parameters were measured using superimposition-based and conventional cephalometric methods to describe the craniofacial changes. RESULTS: The jaws showed significant anterior growth from T1 to T2, and significant retrognathism from T3 to T4. The anterior face height and jaw dimensions increased significantly until T3. Significant posterior rotation of the mandible and opening of the vertical jaw relation, in addition to significant retroclination of the incisors and straightening of the facial profile, were found from T3 to T4. LIMITATIONS: Given the small sample size at T4, it was not possible to analyse the gender dimension. CONCLUSIONS/IMPLICATIONS: Craniofacial changes continue up to the sixth decade of life. These changes are consistent, albeit to a lesser extent, with the adolescent growth patterns for most of the studied parameters, with the exceptions of incisor inclination, sagittal jaw position, vertical jaw relation and inclination, and posterior face height.

Early extractions of premolars reduce age-related crowding of lower incisors: 50 years of follow-up.

OBJECTIVES: To study the effects of extraction of four premolars, without subsequent orthodontic treatment, on the crowding of lower incisors in subjects between early adolescence and late adulthood, as compared to untreated subjects. MATERIALS AND METHODS: A total of 45 subjects were included in this study. The extraction group comprised 24 subjects who had all the first premolars removed at a mean age of 11.5 years, to relieve crowding in a class I malocclusion without subsequent orthodontic treatment. The control group had 21 untreated subjects, having a normal occlusion at a mean age of 13.0 years. The participants were documented with dental casts and cephalograms at mean ages of 11.4 and 13.0 years, for the two groups respectively (T1), and at mean ages of 30.9 years (T2) and 61.7 years (T3). Changes in lower incisor crowding were described as changes in "irregularity" and "space deficiency." RESULTS: The extraction group showed no changes in the irregularity of the lower incisors and significant improvement of the space deficiency of the lower teeth into late adulthood. While in the control group, both irregularity of the lower incisors and space deficiency of the lower teeth increased significantly into late adulthood. CONCLUSION: Lower incisor alignment remains mainly unchanged into late adulthood in subjects who have all their first premolars removed in childhood, as the only treatment to relieve teeth crowding. CLINICAL RELEVANCE: Severe crowding in a class I occlusion can be solved solely with premolar extraction, allowing for spontaneous adjustments with more stable incisor alignment up to late adulthood.

A Superimposition-Based Cephalometric Method to Quantitate Craniofacial Changes.

To assess the craniofacial changes related to growth and/or to orthodontic and orthognathic treatments, it is necessary to superimpose serial radiographs on stable structures. However, conventional superimposition provides only a graphical illustration of these changes. To increase the precision of growth and treatment evaluations, it is desirable to quantitate these craniofacial changes. The aims of this study were to (1) evaluate a superimposition-based cephalometric method to process numerical data for craniofacial growth changes and (2) identify a valid, reliable, and feasible method for superimposition. Forty pairs of cephalograms were analyzed at T1 and T2 (mean age 9.9 and 15.0 years, respectively). The superimposition-based cephalometric method involved relating the sagittal and vertical measurements on the T2 radiographs to the nasion and sella landmarks on the T1 radiographs. Validity and reliability were evaluated for three superimposition methods: the sella-nasion (SN); the tuberculum sella-wing (TW); and Björk's structural. Superimposition-based cephalometrics can be used to quantify craniofacial changes digitally. The numerical data from the superimposition-based cephalometrics reflected a graphical illustration of superimposition and differed significantly from the data acquired through conventional cephalometrics. Superimposition using the TW method is recommended as it is valid, reliable, and feasible.

Nickel allergy in relation to piercing and orthodontic appliances--a population study.

BACKGROUND: Studies have shown conflicting results on the association between nickel exposure from orthodontic appliances and nickel sensitization. OBJECTIVES & METHOD: In a cross-sectional study, we investigated the association between nickel sensitization and exposure to orthodontic appliances and piercings. 4376 adolescents were patch tested following a questionnaire asking for earlier piercing and orthodontic treatment. Exposure to orthodontic appliances was verified in dental records. RESULTS: Questionnaire data demonstrated a reduced risk of nickel sensitization when orthodontic treatment preceded piercing (OR 0.46; CI 0.27-0.78). Data from dental records demonstrated similar results (OR 0.61, CI 0.36-1.02), but statistical significance was lost when adjusting for background factors. Exposure to full, fixed appliances with NiTi-containing alloys (OR 0.31, CI 0.10-0.98) as well as a pooled 'high nickel-releasing' appliance group (OR 0.56, CI 0.32-0.97) prior to piercing was associated with a significantly reduced risk of nickel sensitization. CONCLUSION: High nickel-containing orthodontic appliances preceding piercing reduces the risk of nickel sensitization by a factor 1.5-2. The risk reduction is associated with estimated nickel release of the appliance and length of treatment. Sex, age at piercing and number of piercings are also important risk indicators. Research on the role of dental materials in the development of immunological tolerance is needed.

Lifestyle and nickel allergy in a Swedish adolescent population: effects of piercing, tattooing and orthodontic appliances.

The aim of this study was to estimate the prevalence of life-style practices in adolescents and their association with nickel allergy. Upper secondary school pupils (n = 4,376; 15-23 years) were patch-tested for nickel aller-gy, follow-ing completion of a questionnaire (answered by 6,095). Almost 86% girls and 21% of boys reported piercing. More girls (6%) than boys (3%) had a tattoo. Twenty-six percent of the girls and 18% of the boys were regular smokers. Vegetarian/vegan diets were reported by 20% of girls and by 6% of boys. Piercing, female gender, and vocational programme increased the risk of nickel allergy, whereas orthodontic appliance treat-ment prior to piercing reduced the risk of nickel allergy. Pupils in vocational programmes had the highest prevalence of nickel allergy. Lifestyle behaviours are interconnected and cluster in subgroups of adolescents. Female sex, piercing and choice of educational programme are prominent lifestyle markers. A trend shift is observed, where more girls than boys report tattooing.

Orthodontic treatment-related white spot lesions: a 14-year prospective quantitative follow-up, including bonding material assessment.

INTRODUCTION: White spots (WS) related to orthodontic treatment are severe cariologic and cosmetic complications, but they are shown to be partially reduced by remineralization or abrasion in short-term follow-ups. In this prospective study, we quantitatively analyzed changes in WS in general and in treatment-related white spot lesions (WSL) during orthodontic treatment and at a 12-year follow-up after treatment. In addition, we quantitatively compared the effects of an acrylic bonding material vs a glass ionomer cement (GIC) on WSL. METHODS: Sum areas of WS and WSL were calculated on scans of standardized photos of the vestibular surfaces of 4 teeth in consecutive orthodontic patients (median treatment time, 1.7 years) bonded with the 2 materials in a split-mouth design. Comparisons were made in 59 patients before treatment (BF), at debonding (T0), at 1 year (T1), and at 2 years (T2), and in 30 patients at a 12-year follow-up (T3) with the Friedman test followed by pairwise comparisons with the Wilcoxon matched-pairs signed rank test. Differences of the effects of acrylic vs GIC on the sum areas of WSL were tested for each observation period with the Mann-Whitney U test. RESULTS: Increases in the sum areas of WS and WSL from BF to T0 (P <0.001) were followed by significant decreases at T1 (P <0.001) and T2 (P <0.01 for WS; P <0.001 for WSL). Significant changes were also found in the sum areas for WS at T3 compared with T2 (P <0.01), but not for WSL (P = 0.328). The sum areas of WS and WSL at T3 did not return to BF levels (P <0.001). Sum areas of WSL were higher for surfaces bonded with acrylic compared with GIC for each observation period from BF to T2 (P >0.001), and from T2 to T3 (P >0.05). CONCLUSIONS: Although significantly reduced during the 12-year follow-up and significantly lower with the GIC than the acrylic material at bonding, WSL are a cariologic and cosmetic problem for many orthodontic patients.

Nickel allergy--prevalence in a population of Swedish youths from patch test and questionnaire data.

BACKGROUND: The prevalence of body piercing and orthodontic treatment has increased during recent decades. Such changes in lifestyle may influence the occurrence of nickel allergy. OBJECTIVES: The aim of this study was to describe the prevalence of nickel allergy in a Swedish youth population. METHODS: In a cross-sectional survey, 6095 adolescents answered a questionnaire on their lifestyle and medical history, and 4439 consented to patch testing for contact allergy. Patch test results were adjusted for dropouts by a missing value analysis. RESULTS: The prevalence of self-reported dermatitis from contact with metal items was 14.8%. Patch testing showed nickel sensitization in 9.9% of the subjects, and in significantly more girls than boys, 13.3% versus 2.5%, respectively. Taking the dropout into account, the estimated true prevalence of nickel sensitivity evaluated by test reading at D4 is 11.8% in girls and 1.6% in boys. CONCLUSIONS: The prevalence of nickel sensitization was higher for girls and slightly lower for boys compared with previous Swedish data. Self-reported information on metal dermatitis as an estimate of nickel allergy has low validity. When possible, missing value analysis should be performed to account for dropouts.

Nickel in dental plaque and saliva in patients with and without orthodontic appliances.

The aim of this study was to compare the content of nickel in the saliva and dental biofilm in young patients with and without orthodontic appliances. The possible influence of a dietary intake of nickel on recorded nickel levels was examined. Nickel content in unstimulated whole saliva and in dental plaque of 24 boys and girls (mean age 14.8 years) with intraoral fixed orthodontic appliances was compared with 24 adolescents without such an appliance. Sample collection was set up to exclude nickel contamination. Diet intake was recorded for the preceding 48 hours to account for the influence of recent nickel content in food. Saliva and plaque were analysed for nickel content using an electrothermal atomic absorption spectrometric (ETAAS) method. The acidified saliva samples were analysed as Millipore-filtered saliva with filter-retained fractions and plaque following dissolution in acids. No significant difference in nickel content of filtered saliva was found between the test and the control samples (P = 0.607); the median values of nickel content were 0.005 and 0.004 mug/g saliva, respectively. On the other hand, a significant difference was found for the filter-retained fraction (P = 0.008); median values for nickel were 25.3 and 14.9 mug/g, respectively. A significant difference in nickel content between test and control samples was also found in plaque collected at various tooth sites (P = 0.001; median values 1.03 and 0.45 mug/g, respectively). A stronger difference was found when comparing plaque collected from metal-covered tooth surfaces than from enamel surfaces of orthodontic patients. No association could be found between calculated dietary intake of nickel and recorded nickel in the test and control samples. It is concluded that nickel release occurs into the dental plaque and components of saliva of orthodontic patients, a situation that may reflect time dependence of its release from orthodontic appliances into the oral cavity and an aggregation of nickel at plaque sites.

Roentgen-cephalometric standards for a Swedish population. A longitudinal study between the ages of 5 and 31 years.

This study was performed to establish age- and gender-specific cephalometric normative data for a Swedish population. The material comprised 469 lateral cephalograms from two groups of subjects of Swedish origin between 5 and 31 years of age. All subjects (males and females) were diagnosed as 'normal' according to specified criteria and with no history of orthodontic treatment. Lateral cephalograms and body height measurements were taken at 5, 7, 10 and 13 years of age in one group (group E) (longitudinal follow-up). The same registrations were made in the other group (group U) at 7, 10 and13 years of age (mixed longitudinal type). Those 13 year olds were re-examined at 16, 19 and 31 years of age (longitudinal follow-up). No significant differences between age groups in the two samples were found. Therefore, subjects of the same age were combined. The study is hence regarded as a longitudinal follow-up from 5 to 31 years of age. The subjects were also grouped into dental development stages to widen the applicability of the cephalometric data.The craniofacial distances were constantly larger in males than in females, while no statistical differences as regards angular measurements were seen between genders. Distances as well as angular measurements varied with the different developmental periods. The results clearly verify that facial pattern changes existed during the observation period, with a growth acceleration of most distances between the 13 and 16 year recordings.

A 100th anniversary: Sandstedt's experiments on tissue changes during tooth movement.

In 2004, it is 100 years since the experiments by Carl Sandstedt on tissue changes during orthodontic tooth movement were published in an international journal, shortly after his early death.