Dental Tribune United Kingdom Edition

25ClinicalFebruary 14-20, 2011United Kingdom Edition T he main categories of techniques for microin- vasive preparation (MIP) include chemo-mechanical cleaning with Carisolv gel, air abrasion and dental lasers. 1, 2 The trends for the replacement of the conventional method of preparation led to focus the at- tention of researchers on the impact of alternative tech- niques for MIP on hard dental tissues and underlying dental pulp. MIP techniques claim for controlled removal of infected and softened dentin while pre- serve healthy hard dental tissues and do it with minimal discom- fort for the patient. However, currently available data provide contradictory the impact of alternative techniques of MIP on hard dental tissues compared to conventional preparation. Possible reasons for this are the variety of experimental stud- ies and difficulties to standardise the results of clinical researches. It is striking that researchers who give the most positive evaluation of alternative methods of prepa- ration are using mainly clinical criteria for evaluation (percep- tion and tolerance of the patient, noise, atraumatic work, colour and texture of the dentine when probing etc) which are some subjective. Opposite, the SEM and his- tologic evaluations are not unanimous for its benefits and advantages. On the dental market new improved ver- sions of alternative systems for preparation are available claim- ing for clinical efficiency, but scientific data are still scarce (these are generally the mul- ti-frequency high-energy la- sers and air abrasion devices). For that reason periodic updates of researches in this rapidly developing and promising field of dentistry are needed. The purpose of this in vitro study was to evaluate by SEM the ultrastructural changes in the hard dental tissues treated with Er: YAG laser (LiteTouch) and conventional preparation with diamond burs/air turbine and steel burs/micromotor. Methods Experimental design: the study used 30 human teeth freshly extracted due to advanced peri- odontal disease. The preparation involved natural carious lesions on tooth surface. According to the prepara- tion technique the teeth were divided into three groups of 10 teeth (n=10): Group 1: Laser preparation by Er: YAG laser (LiteTouch, Syn- eron, Israel) (Fig 1 a, b) Group 2: Mechanical rotary preparation by diamond burs/air turbine) Group3:Mechanicalrotaryprep- aration by steel burs/micromotor Preparations are made strict- ly according to manufacturer’s instructions for service. The removal of caries is proved by clinical methods – observation and probing. After preparation the teeth are im- mersed for one hour in four per cent buffered fixative solution of glutaraldehyde (0.075 M, pH 7.3). Then rinsed with distilled water and placed for 90min in cold buffer solution of sodium kakodilate (0.02M, pH 7.2, 660 mOsm) for fixation of organic matter. Subsequent dehydra- tion is carried out in ethanol in ascending series of 30, 50, 70, 80, 95 and 100 per cent in one hour in each series, such as dry- ing of the teeth is based on CPD (Critical Point Drier) method in SEM evaluation of morphological changes Georgi Tomov discusses tissues prepared by Er:YAG laser and rotary instruments page 26DTà