Heat Generation by Diode Laser ( 1064-nm ) on Dental Implants . ( An in vitro study )

Aims: The aim of this study was to assess temperature changes of dental implant body when using different wattage of diode laser (Fox laser 1064-nm) and set a proposed power setting that has no detrimental effect on adjacent bone. Materials and Methods: Seventy-five Titanium implants with healing screws were used in this study. Thermocouple technology was used to measure the temperature level generated in the dental implant body when being exposed to laser. The implants were fixed in an acrylic mandible model and then placed in a controlled water bath at 37 °C. Time to reach a temperature degree of 47 °C were recorded after each wattage as well as the dropping time of temperature to reach a degree of 37° C was recorded. Results: The decrease in time needed to reach 47 °C was directly related to an increase in wattage and as such the time is inversely related to wattage. All the recording time measures dropped to 37 °C with no significant differences. Conclusion: It can be concluded that using diode laser in at 6 wattages with pulsed wave settings produced high temperature with minimum time compared when using 2 wattage settings which needed more time to produce the same heat


INTRODUCTION
The use of endosseous implants in dentistry has increased dramatically over the last 20 years (1,2). With dental implant therapy complications may occur which could either be prosthetic or biological complications or both. Suc-Heat Generation by Diode Laser (1064-nm) on Dental Implants. (An in vitro study) cess has been demarcated recently (3)(4)(5) . Periimplantitis is the most common biological complication around dental implants. A current consensus report concluded that peri-implantitis is a bacterially induced inflammation of the supporting peri-implant tissues leading to nonreversible bone destruction (6)(7)(8). The incidence of peri-implantitis fluctuates from 11.3 to 47.1% after 8 years. (9) Numerous treatments have been recommended for peri-implantitis in the literature such as physical method plastic curettes, scaling, ultrasound. (10) , local chemical antibiotics, antiseptic solutions. (11) systemic methods, (12) or a combination of these. (13,14) The use of laser in the dental field has encouraged research for determining its effectiveness in the treatment of peri-implantitis. (15,16) The revolution for dental laser came in the middle of the 1990s. Many laser types with corresponding wavelengths, diode laser rapidly began establishing itself as a compact, competitively priced, and versatile accompaniment to the dentist's collection mostly used on soft tissue applications (17) Diode lasers can be used for numerous dental events which are frequently soft tissue procedures. (18,19) Diode lasers have been suggested for uncovering submerged implants. (20,21) decontaminating implant surfaces when treating peri-implantitis (22) and, periodontal pocket therapy (23). The thermal effect of laser beams on implant surfaces is widely studied. These studies have revealed that thermal injury at the bone-implant site impedes the regenerative reaction of bone healing, hence reducing osseointegration leading to subsequent implant mobility. (24)(25)(26) It has been established that if bone is warmed up to a temperature of 47°C for one minute, bone necrosis, which obstructs the osseointegration of an implant, can occur. However, heating to temperatures lower than 47°C did not seem to affect the bone tissue at the microscopic level, but vascular injury, as evidenced by increased capillary leakage, could not be excluded at even lower temperatures. (27) The aim of the current invitro study was to assess temperature changes of dental implant body when using different wattage settings of diode laser (Fox laser 1064-nm) and set a proposed power setting that has no detrimental effect on adjacent bone.

MATERIALS AND METHODS
This study was conducted at the depart-  ic temperature-control device maintaining the water temperature at 37°C (C.K type KI&BNT made in china) was used ( Figure 3). Thermocouple electrodes (K-type made in china) were used to measure the temperature ( Figure 3). An electronic timer was used to record reading in seconds (28).
Dental implants with an SLA surface with 3.3mm in diameter and 10 mm in length were inserted in the mandible model by using a mo-tor system of dental implant preparation which began with an initial Linderman drill (2.2 mm) then a first drill (2.6 mm) followed by final

RESULTS
The mean time required to raise the temperature to 47°C at 2 watts was (126)    showed no significant differences between all groups as shown in Figures (4,5).

DISCUSSION
The eradication of microorganisms by diode laser though established by numerous studies has some aspects when used for the treatment of peri-implant disease in that the laser beam may disturb the implants titanium surface (29)(30)(31) .
Such a type of laser and with its power parame-  (32) . In some studies, bone injury by heat induction was carried out in rabbits causing adverse effects on living bone when the temperature rised above 47°C for 60 s affecting the ability of bone to regenerate (27,33,34) . The overheating at the bone-implant interface may cause bone death and compromise the bone's ability to stay alive as a differentiated tissue (35) . Temperatures be- yond 50 C are widely believed to promote thermonecrosis (36)(37)(38) . It has been established that bone is more sensitive to temperature than formerly supposed, and it will withstand a threshold temperature ranging from 44°C to 47°C for only 1 minute without impaired bony regeneration. However, increasing the temperatures but lower than 47°C did not appear to affect the bone tissue at the microscopic level, but vascular harm did occur as evidenced by increased capillary leakage at even lower temperatures (27) . The result of this study came parallel with the results of Matys, J., et al whom showed that the temperature on the implant interface increases as the laser power increased (32) . Leja, C., et al showed that lower laser power settings and pulsed rather than continuous mode took longer to reach critical temperature (39) . The main limitation of the current study was the lack of evidence of this type of laser on the surface topography of implant.
However, there are studies in this field that can give us some clue on its effects. Particular care should be taken when using lasers in its different types for treatment of peri-implantitis such as Er: YAG, CO2, Diode, Er,Cr:YSGG(Erbium, Chromium doped Yttrium Scandium Gallium Garnet) and Nd:YAG (Neodymium-Doped Yttrium Aluminium Garnet (40,41) .