An Experimental Study of Er：YAG Laser for Implant Hole Preparation

Abstract

Purpose:Implant hole preparation using conventional drilling instruments is sometimes unsatisfactory due to the need to apply undue pressure. A recent study reported that an Er:YAG laser proved better with little constraint on the positioning of the laser tip. There have been reports on histological evaluation of osseointegration in comparable sites prepared with an Er:YAG laser and with traditional drills. The aim of this study was to assess the feasibility of an Er:YAG laser (Lite Touch™, Syneron, Israel) and its effectiveness by comparing laser exposure time with depth of bone hole in an experiment using the mandible of a beagle dog.
Materials and methods:A postmenopausal beagle dog was used. The laser was irradiated at three sites of the buccal bone surface of the mandible. Point A:a site over the mandibular canal;point B:the corresponding site under the mandibular canal;and point C:the buccal bone surface at the inferior margin of the mandible. The irradiation output was 8.4 W (700 mJ ×12 Hz) on the chip. The volume of spraying water was about 30 mL/min. The sapphire laser tip was 19 mm by 1.3 mm. The exposure time at points A and B was 5 sec and that at point C was 1,2,3,5 and 10 sec (n=5).
Results and discussion:The average depth of bone hole made by 5-sec laser irradiation at points A and B was 4.7±1.4 mm and 5.6±0.4 mm, respectively. It was surmised that at both points the drilling speed was 1.4 or 1.5 mm/sec for the first 3 sec through cortical bone, increasing to 1.8 mm/sec through cancellous bone. At point C, the speed increased gradually with an average of 0.7±0.1 mm at 1 sec, 1.0±0.1 mm at 2 sec, and 1.5±0.2 mm at 3 sec (with a 3-sec average speed of 0.5 mm/sec). The average speed at 5 sec and 10 sec was 1.7±0.2mm and 1.6±0.1 mm, respectively. The nature of cortical bone seems to prevent the speed from increasing.
Conclusion:The Er:YAG laser in the study required no pressure application, giving precise results with little constraint on the positioning of the laser tip. Bone holes were formed in a straight line. The preparation speed of a bone hole relative to laser irradiation time was slow and the depth seemed limited in cortical bone, whereas the speed increased through cancellous bone. The Er:YAG laser was shown to be useful for preparing implant holes with almost no technical constraints.