Maurits Persson

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.

Facial morphology and open bite deformity in amelogenesis imperfecta:A roentgenocephalometric study

Occlusal conditions and skeletal facial morphology in patients with amelogenesis imperfecta were studied in order to reveal a supposed relationship between skeletal morphology and a high prevalence of open bite. Records and dental casts were available for 26 cases, and lateral cephalograms in 19 of these. An open bite was present in 11 patients of both sexes, but was more frequent in males than in females. It occurred in cases with enamel defects of hypomineralisation type as well as in those with hypoplasia.15 linear and 10 angular measurements from the cephalograms were compared with those of matched controls. Both males and females with enamel defects were found to have significant skeletal features, characteristic of the so-called open bite skeletal deformity. The skeletal deviation was more marked in males than in females. The pattern of an open bite skeletal deformity, although less marked, was also present in patients with the enamel defect but without an open bite occlusion. The open bite occlusio...

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.

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.

The relationship between mandibular morphology and apical root curvature in man

Two samples of individuals, a low-angle group and a high-angle group, were selected on the basis of the inclination of the lower border of their mandible, defined by the mandibular plane angle (ML/SNL) in profile radiographs. Apical root curvature of mandibular first and second premolars and molars on panoramic radiographs was compared between the two groups and related to mandibular morphology. In the low-angle group most teeth had more distally curved roots than in the high-angle group. Significant differences were found for the first premolars on both sides (p less than 0.001, p less than 0.05), the right second premolars (p less than 0.05) and the distal root of left first molars (p less than 0.05). Correlations were calculated between root curvature and two variables reflecting mandibular morphology, the mandibular plane angle and the gonial angle. The strongest associations were found between the first premolar roots and the gonial angle (rs = -0.75, p less than 0.001 and rs = -0.56, p less than 0.01, for right and left sides respectively). The association between mandibular morphology and root curvature is probably indirect, caused by tooth migration during root formation.