Er-YAG LASER AND DENTAL CARIES TREATMENT

Keywords:laser, treatment, dental,  Time:09-12-2015

INTRODUCTION:

Its higher safety compared to conventional techniques because it does not use rotating instruments in a small mouth which can move unpredictably [1], its minimally invasive nature because of the affinity of the medical laser fibers beam for carious structures and decontamination of ablated dentin [2, 3], the possibility for achieving an effective ablation without thermal negative effects on underlying structures and tissues [4, 5], the increased children cooperativeness during the caries treatment process because of the non contact method used that induces less vibration and provides a painless and more comfortable treatment [6, 7, 8] are only a small part of the Er:YAG laser advantages described in the literature. The laser ability to remove hard dental structures depends on different factors such as water and fluoride content of the target tissue, and laser parameters including energy,pulses per second, water spray, the tip material, shape and diameter [9, 10]. Different studies reported very good clinical results after using of Er:YAG laser in the caries treatment in adults [11, 12]. However, there is a lack of clinical studies in the literature with regard to the Er:YAG laser application in dental caries treatment in childhood.

Tasks:

1. Proposal for a protocol with recommended Er:YAG laser parameters for cavity preparation and removal of carious hard dental structures in permanent teeth in children;
2. Assessment of the clinical success of Er:YAG laser caries treatment after applying of the same protocol in dental clinical practice.

Tasks: 1. Proposal for a protocol with recommended Er:YAG surgical laser fibers parameters for cavity preparation and removal of carious hard dental structures in permanent teeth in children; 2. Assessment of the clinical success of Er:YAG laser caries treatment after applying of the same protocol in dental clinical practice.

MATERIALS AND METHODS:

Fifty children (21 male and 29 female) between the age of 6 and 16 years with a total of 116 cavitated carious dentinal lesions participated in this study. Of these, 24 children were aged from 6 up to 11 and had 48 cavitated carious dentinal lesions on first permanent molars and 26 children were aged from 12 up to 16 and had 68 carious dentinal lesions on first incisors, canines, first and second permanent molars. Inclusion criteria: - good general health; -  at least one bilateral matched pair of one type cavitated carious lesions with regard to: - the tooth – incisors, canines, premolars or molars; - location of the lesion – cervical, occlusal or proximal; - cavity depth – less or more than second half of dentine. Exclusion criteria: - symptoms (evidence) of complicated caries (pulpitis or apical periodontitis); - poor oral hygiene. Informed written consent was obtained for the procedure of laser and conventional treatment from each patient’s parents, as required by the institution’s Ethics Board. Ten permanent incisors, 6 upper permanent canines,44 lower first permanent molars, 30 upper first permanent molars and 26 lower second permanent molars cavities were prepared. Sixteen of the lesions were in the cervical area of teeth, 38 were proximal lesions and 60 occlusal lesions. Thus, all three possible types of carious lesions were prepared using the laser. Ninety four of the lesions were at the dentin-enamel junction and the remaining 22 in the second half of the dentin. A split-mouth design was used. One of the cavities was prepared conventionally, the other with an Er:YAG laser in each patient. For laser preparation, an Er:YAG laser (Lite Touch™, Syneron, Israel) with a wavelength of 2940 nm and pulse duration: 50 ìsec. tat is a solid-state crystal laser with the host crystal-Yttrium Aluminum Garnet doped with Erbium ions that replace the Yttrium ions was used. Hard dental structures’ ablation is getting performed with a sapphire tip, working distance of 0.5-1.0 mm and airwater cooling of 39 ml/min. The clinical protocol with recommended Er:YAG laser Lite Touch parameters was drawn on the base of our previous Scanning Electron Microscope (SEM) and Raman and Infrared reflection microspectroscopic study on permanent human enamel and dentin [13, 14].  Parameters of the laser used in carious lesions treatment of permanent teeth are presented on table 1:

The exposing of carious lesions with occlusal location (small pit and fissure carious lesions) starts with a sapphire tip tilted toward fissure at angle of 25 ° to the axial axis of the tooth. Once the ablation occurs, the tip is pointed toward the carious fissure perpendicularly (angle of 90 - 100 ° to the occlusal surface). At wide fissure carious lesions the exposing is conducted with an angle of 90 - 100 ° toward the fissure. The interproximal location requires the sapphire tip to be pointed at angle of 90 ° to the occlusal surface of the enamel that has to be removed. Er:YAG laser exposing of carious lesions with cervical location is getting conduct with a working angle of 110 -120 ° to the cervical enamel surface. In mechanically prepared cavities, high-speed and low-speed water-cooled handpieces with burs were used. The excavation in both groups was carried out under visual control with intermittent testing of hardness of the remaining hard structure by means of a dental probe [15] observing the principle of dental caries treatment with minimal intervention- removing of the infected layer leaving the affected one only on the pulpal wall of the cavity prepared. All cavities were restored with a nanohybrid composite (Calore GC) and adhesive system 3M ESPE Scotchbond Multi-purpose (SBMP) in accordance with manufacture recommendations. In the deepest carious lesions, calcium hydroxide liner was used prior to placing one of the filling materials. The two cavities (one prepared conventionally, the other with an Er:YAG laser) were completed at two separate appointments, on different days. No local anesthetic was used either before or during the treatment.

The evaluation of clinical effect of Er:YAG laser application in dental caries treatment of permanent teeth was conducted at baseline, 6, 12, 18 and 24 months using FDI Recommendations for Conducting Controlled Clinical Studies of Dental Restorative Materials, updated in 2008 (table 2). The application of these criteria provides the opportunity of the clinical evaluation of restorations not only involving the restorative material per se but also different operative techniques [16].

Two step approach for assigning scores for each parameter was used: the first step was to assess the restoration and to determine the level of clinical acceptability for each parameter in each of the categories (the result becomes unacceptable whenever re-treatment is necessary or highly advisable with exception of secondary caries and marginal adaptation where even a minimally-invasive approach need requires score unacceptable); as a second step a further distinction was made between an excellent, good and clinically satisfactory result [17, 18]. Postoperative hypersensitivity was recorded at the time of restoration placement, at baseline and at all recalls visits, and included type of pain, discomfort and duration on dry ice stimulus at clinical assessment. Intensity was assessed with a Wong-Baker scale [19]. Clinical evaluation of secondary caries and marginal adaptation was done with a loop (magnification 4 X), after tooth brushing with a paste.