Effectsof intra-oral metal restorations on shortwave diathermy

Objectives: Shortwave diathermy can increase the body temperature in deeper areas of the probe. However, it is recommended to avoid placing metal objects in locations where the shortwave can reach. For this reason, studies on shortwave diathermy have been excluded from dentistry. The purpose of this study was to determine the effect of shortwave diathermy on oral floor temperature as well as the effect of metal restoration on this therapy. Methods: Twenty healthy subjects with a mean age of 27.9 years participated in this study. Subjects were divided into 2 groups: those with metal restorations (MR, n = 10) and those without metal restorations (metal-free, MF, n = 10). Shortwave diathermy (SW-201 Ito Co., Ltd.Tokyo) was applied from both sides of the mandibular angle for 20 minutes, and the temperature of the oral floor was monitored by an alcoholic thermometer every one minute during shortwave exposure and 5 minutes after completion of exposure. Two-minute resting saliva collections were performed before and after exposure. Ion concentration, amylase and salivary stress biomarkers, cortisol, and chromogranin A were measured. Students't-test was used for statistical analysis, and p < 0.05 was set as significant. Results: No discomfort was reported from the subjects during the entire experiment. Shortwave diathermy significantly increased oral temperature from the baseline: 0.35 ± 0.07 degrees for MR and 0.84 ± 0.20 degrees for MF. Shortwave exposure significantly increased resting saliva for both MR and MF. Saliva analysis revealed that the saliva amylase concentration from MF significantly increased upon exposure, but stress biomarker levels remained unchanged, suggesting an increase in parotid saliva. Conclusions: Shortwave diathermy increased oral temperature, which resulted in upregulation of resting saliva secretion, especially parotid saliva secretion. Further studies are needed for the safe use of this equipment because a shielding effect was observed with MR.