Analysis of intrapulpal temperature rises after application of Er:YAG laser with various parameters on different thicknesses of primary teeth dentin tissue

Primer treatment of diseases of dental hard tissues is the removal of changed tooth structures due to dental caries. The methods used to remove dental caries developed over the years. However high-speed rotary instruments which have become a traditional method and most commonly accepted by dentists can remove dental caries easily and fast, the negative effects such as voice, pressure, vibration, hypersensitivity and temperature rise made examiners search for alternative methods of cavity preparation.Since 1960 laser light records a large extent of development in the diagnosis, treatment and preventive disciplines of medicine. Also there have been many researchs that showed laser light as an alternative to conventional treatment methods in soft and hard tissue procedures in dentistry. Erbium: Yittriyum Aluminum Garnet (Er: YAG) lasers were approved for the method of removal of dental caries by FDA (Food and Drug Administration) in 1997 and have been used commonly in Pediatric Dentistry. As well as painless and non-contact treatment modality of Er:YAG laser has given the dentist the advantage of increasing patient comfort, the effectiveness of Er:YAG lasers in removing dental caries and increasing the adhesion of adhesive systems to dental hard tissues have been shown by in-vivo and in-vitro researchs. Also histopathological effects of Er:YAG lasers on primary teeth pulp tissue are evaluated in many researchs.The biggest problem of current laser systems announced, is heat effect on dental tissues after application of lasers with high energy levels. There are many in-vivo and in vitro studies about the effects of temperature changes in pulp tissue of permanent teeth. However, there are very few studies showing the effect of temperature changes in pulp tissues of primary teeth. Therfore this study aims to determine and compare the possible heat effects in the pulp chamber of primary teeth after the application of Er:YAG laser and high speed rotary instrumentThe study included 60 primary second molar teeth. The root section of teeth was cut longitudinally and bucco-lingually to calculate the temperature increases in the pulp chamber. Pulp tissue in the pulp chamber were removed. Black 5 cavity preparations on dentin tissue were performed by Er: YAG laser (5 W, 3.75 W, 2.25 W, 1.5 W) and a high-speed rotary instrument with the aid of water cooling after enamel was completely removed on the buccal surface of the teeth. Thermocouples attached to a calibrated digital thermometer were placed inside the pulp chamber to evaluate temperature changes that is expected to occur in the pulp chamber. The difference between the temperature values in the beginning and the end of the cavity preparations and the highest temperature rise value were recorded for every sample.5W Er:YAG laser group has significantly higher temperature rise values than all groups. 1,5W Er:YAG laser group has significantly lowest temperature rise values. Increases in temperature values of the pulp chamber were seen while the depth of cavity was increased in all groups.The average pulp chamber temperature rises were not exceeded the critical temperature value of 5.5 ° C that causes irreversible pathological conditions in pulp tissue, after cavity preparation with Er: YAG laser and high-speed rotary instrument, in this study. According to the results of the study, the effective cooling with water spray in all groups was essential for the lower temperature rises. It can be concluded that the working parameters of Er:YAG laser used in this study for cavity preparation in primary teeth dentin tissue may be safe without causing a temperature increase that has negative impact on primary teeth pulp tissue in present study.