Disputas: Lino Thorlakson
Lino Thorlakson vil forsvare sin avhandling for graden ph.d.: Microbiological, clinial and 3-dimensional features of white spot lesions in permanent teeth
Tid og sted for prøveforelesning
- Professor PhD Ann Progulske-Fox, College of Dentistry, University of Florida - førsteopponent
- Professor, PhD Theodore Eliades, Department of Orthodontics and Paediatric Dentistry, Center of Dental Medicine, University of Zürich - andreopponent
- Professor Tiril Willumsen, Det odontologiske fakultet, Universitetet i Oslo - komiteens leder
Leder av disputas
Prodekan for studier Anne Merete Aass
The thesis is based on two papers that describe in vivo experimental studies of microbial community succession on human enamel in patients with fixed orthodontic appliances and on one paper that explores correlations between color and volume of white spot lesions in order to determine if prediction of lesion depth is possible. The overall aim was to gain a better understanding of white spot lesions.
In the first paper white spot lesions were generated in vivo on 23 human teeth (8 patients, 10-14 years old) predetermined to be extracted for orthodontic reasons. The bacterial microbiota on sound enamel and on developing carious lesions was identified using the Human Oral Microbe Identification Microarray (HOMIM). The microbial community composition of the plaque over white spot lesions differed significantly as compared to that over sound enamel. The bacterial community composition associated with the progression of enamel lesions was found to be specific and much more complex than previously believed.
The aim of the second paper was to determine how fixed orthodontic appliances affect the microbiota of supragingival plaque over 5 months. Twenty individuals of Scandinavian origin, aged 10–16 years, were included. All subjects were fitted with fixed orthodontic appliances in both the maxillary and mandibular tooth arches. Plaque microbiota was identified using HOMIM. The prevalence of gingivitis at the maxillary central incisors increased from 25% at T1 to 74% at T4. Trends toward a microbiota containing more periodontitis- and caries-associated bacteria were detected; however the changes were not severe enough to be significant.
In the third paper the volume of white spot lesions was calculated by using microcomputed tomography and compared to the clinically visible white spot lesion surface area and its color intensity. The white spot lesions were induced in 8 patients in vivo on 23 healthy premolars destined for extraction during orthodontic treatment by using specially designed plaque-retaining orthodontic bands. A significant correlation was found between white spot lesion color intensity and lesion volume. Our results indicate that white spot lesion color intensity might predict the depth of enamel remineralization as well as or better than traditional white spot lesion scoring. Therefore, the dentist could use this information when planning treatment for white spot lesions.