**9.4 Dental caries determination**

322 Contemporary Approach to Dental Caries

using a CLSM system (Fontana *et al*., 1996). The major advantage of this method is that it enables quantitative analysis of thick samples without the problems of thin section preparation required for microradiography or polarized light microscopy. Essentially, CLSM allows a subsurface examination since the scattered, reflected, and fluorescent light from planes out of focus is eliminated – providing a subsurface image only from a thin layer upon which it is focused. This processed digital image can be used to determine surface features, area and volume analysis of given structures, and views of the total structure from any angle in three dimensions. In terms of efficacy, a statistically significant high correlation was found between mineral changes measured using microradiography and the changes in

lesion parameters analyzed by confocal microscopy (González-Cabezas *et al*., 1998)

of this chapter are to highlight the results of two recent studies that investigated:

records; and

**9.1 Selection of subjects** 

labial tooth surfaces;

**9.2 Chart abstraction** 

**9.3 Photography** 

**9. Methods and materials: Part I** 

record selection consisted of patients who:

With all the treatment modalities flooding the marketplace, the orthodontist might find it difficult to sort out what works best and why when oral hygiene deteriorates. The objectives

1. The incidence of new WSLs before and after orthodontic treatment using photographic

2. The potential of ACP-containing resin cement and other treatments (fluoride varnish, resin sealer, MI Paste) to prevent incipient caries lesions next to bracketed teeth.

From a population of 2,296 patients treated in the graduate orthodontic clinic at the University of Michigan School of Dentistry (UMSD) between 1997 and 2004, 350 patient records were selected randomly using a random number sequence. Inclusion criteria for

1. Underwent comprehensive orthodontic treatment utilizing full fixed appliances on

Data collection from de-identified patient charts included gender and age at initiation of orthodontic treatment, and treatment variables such as extraction therapy and comprehensive treatment time. Comprehensive treatment time was defined as the period between initiation of full fixed appliance therapy and removal of all active fixed appliances. Initial oral hygiene score, frequency of oral hygiene discussion, oral hygiene instruction and

Intraoral pre-treatment (initial) and post-treatment (final) photographs of each patient were taken as part of standard orthodontic recordkeeping procedures. All photographs, stored as 35 mm slides, were taken in the Clinical Photography Department at the UMSD by two professional photographers utilizing a standardized intraoral photography procedure.

fluoride application and/or rinse were recorded from progress notes in the chart.

2. Had complete initial and final series of intraoral photographs; and 3. Had complete treatment log information within their chart.

Images were evaluated by trained investigators using a scoring system specifically adapted for use with photographed images (*International Caries Detection and Assessment System II*; Ismail, 2005). Visible labial surfaces examined included maxillary and mandibular central and lateral incisors, canines, first and second premolars, and first molars. The evaluators scored each visible labial tooth surface before and after orthodontic treatment. The scores were combined to determine the labial caries incidence for each patient. Teeth were examined and scored from first molar to first molar, maxilla and mandible (Fig. 2).

Fig. 2. Tooth labial surfaces were examined and scored from left first molar to right first molar, maxilla and mandible, before and after orthodontic treatment.

White-Spot Lesions in Orthodontics: Incidence and Prevention 325

Teeth were exposed to a pH cycling system to develop caries-like lesions. Each day teeth were incubated in demineralization solution (lactic acid and Carbopol [pH = 5.0], 50% saturated with hydroxyapatite) for eight hours, rinsed with de-ionized water and placed in artificial saliva for 30 minutes, followed by two seconds of brushing with a powerbrush (Sonicare, Philips) and fluoridated dentifrice (NaF, 1,100 ppm F), rinsed again and placed

Solutions were refreshed daily during the experimental period of 15 days. On day 15, all teeth were removed from the saliva solution, rinsed under tap water and stored in 100% humidity. To assess demineralization, Quantitative Light-induced Fluorescence (QLF) and Confocal Laser Scanning Microscopy (CLSM) were used. Both procedures were carried out

back in artificial saliva until next demineralization period (next day).

**11.2 Demineralization protocol** 

Table 1. Incidence of white-spot lesions (WSLs)

at the Oral Health Research Institute (IU) in Indianapolis, IN.

#### **10. Results: Part I**

The overall incidence of patients who developed at least one WSL during orthodontic treatment was 72.9% (N = 255; Table 1 and Fig. 3), while for newly developed cavitated lesions that were unrestored on the final record was 2.3%. Of the eight patients that developed cavitated lesions during orthodontic treatment, four (1.1%) developed one new cavitated lesion, three (0.9%) developed two new cavitated lesions and one (0.3%) developed four new cavitated lesions. Of the maximum 24 surfaces investigated per patient, on average 4.2 surfaces in each patient showed new WSL. The average of surfaces with new cavitations was only 0.04 and 0.05 with restorations. Even though infrequently, some early WSL regressed to sound (0.07 per patient). Demographic variables of gender and age at initiation of treatment were not related significantly to development of new decalcified or cavitated lesions. There was a significant relationship between increased treatment length and number of newly developed lesions (*P* = 0.03; Table 2). The mean number of labial surfaces per patient that developed new WSL was 3.01 for patients with a treatment length of less than 22 months. This increased to 5.28 teeth for patients with therapy longer than 33 months. The number of new cavitations, however, showed only a nonsignificant trend (*P* = 0.08) with increased treatment time. In addition, the number of newly developed lesions (both WSL and cavitations) showed no significant association with extraction or nonextraction treatment protocols (Table 3). Although no relationship was demonstrated between pretreatment oral hygiene scores and lesion development, the recorded number of oral hygiene discussions between provider and patient were associated significantly with development of both white-spot (*P* <0.0001) and cavitated (*P* = 0.0006) lesions. The mean number of new lesions for patients with whom oral hygiene discussions had never been noted in the chart was 3.08, while the mean number of decalcified lesions for patients who were given oral hygiene instruction on three or more occasions increased to 7.78. A similar increase was exhibited for the mean number of cavitated lesions for patients given three or more oral hygiene discussions (mean = 0.20) *vs.* those with whom oral hygiene was not discussed after initial instruction (mean = 0.01). Age group (*P* = 0.03), treatment length (*P* = 0.01) and number of oral hygiene discussions (*P* < 0.0001) were associated with development of WSL. There was a decrease in WSLs associated with increasing age group (regression coefficient = -0.59). An increase in WSLs was associated with both increased treatment time (regression coefficient = 0.07) and increased number of oral hygiene discussions (regression coefficient = 1.88).
