Pulpal effects of electrosurgery involving based and unbased cervical amalgam restorations

Intrapulpal temperature changes during root surface irradiation with an 809-nm GaAlAs laser

OBJECTIVE

The aim of this study was to explore, in vitro, whether the irradiation of human root surfaces with a diode laser might induce nonphysiologic intrapulpal temperature elevations and, therefore, jeopardize pulp vitality.

STUDY DESIGN

The pulps were removed from human maxillary and mandibular incisors extracted for periodontal reasons. The root canals were enlarged to an apical size #60 file. The teeth were radiographed with standard dental films and a millimeter grid to determine root thickness. The thickness of dentin between the root surface and the pulp in the irradiation areas was 1, 2, and 3 mm. To determine intrapulpal temperature changes during laser irradiation, 0.5-mm K-type thermocouples were inserted. An 809 nm GaAlAs laser with a 400-micron optical fiber was used. The power output varied between 0.5 and 2.5 W in the continuous-wave mode (0 Hz). Irradiation was continued for up to 120 seconds.

RESULT

Temperature elevations between 0.5 and 32.0 degrees C were registered in an energy- and time-dependent manner. Dentin thickness had a significant effect on intrapulpal temperature changes (Mann Whitney U test, P <.05), with a thinner dentin layer resulting in higher temperature elevations.

CONCLUSION

Diode-laser irradiation may jeopardize pulp vitality. It must be recommended to limit power output to 0.5 W and the time of irradiation to 10 seconds when lasing the root surfaces of lower incisors and first maxillary premolars. With other teeth, a power output of 1.0 W and an exposure time of 10 seconds must not be exceeded to ensure a safe clinical application.

Comparison of monopolar and bipolar electrosurgical modes for restorative dentistry: a review of the literature

This review of the literature was undertaken as part of a wider investigation of effective hemostasis in vital pulp therapy. Two general types of electrosurgical units are available: monopolar and bipolar. This review compares the features of both systems. An important hazard referred to as channeling, funneling, or current crowding is described and associated with pulp therapy injury for the first time. Important safety features of bipolar electrocoagulation are identified and applied to dental procedures. Articles were selected by means of a search of MEDLINE, the U.S. National Library of Medicine's bibliographic database, for literature published between 1966 and 2001 on the topics of electrosurgery, electrocautery, electrolysis, and lasers. A search also was completed from a pulp therapy perspective to determine the use of electrosurgery on the pulp. Numerous articles and texts published between 1900 and 1965 had been reviewed previously; their bibliographies were explored and cross-referenced for pertinent reports. Laparoscopic applications of electrosurgery were reviewed for general background information and for clarification of safety and hazard issues; no exclusionary criteria or date limitations were imposed. Beyond the literature review, numerous authors and developers in the field of electrosurgery were contacted for clarification of concepts and controversies. More than 120 articles and texts related to electrosurgery were reviewed, and another 100+ articles were reviewed in the area of pulp therapy.

Electrosurgery--a biological approach

Electrosurgery has been used in dentistry for more than 50 years. Both opponents and advocates of electrosurgery have presented a variety of clinical studies in favour of their respective opinions, which are discussed in the following review. In some studies, wounds created by electrosurgical techniques were observed through the healing stages, in comparison to those following incision by a surgical blade, with no significant difference being discovered. Other studies reported that the histologic response of oral connective tissue to electrosurgery was adverse in some animal and human models. However, neither of these groups used methods that allowed documentation or control of operating variables. A critical evaluation of controlled clinical studies shows that adverse responses of (connective) tissue, epithelium, bone, cementum, and periodontal attachment are related to an excessive lateral heat production during the procedure. With electrosurgery, the clinician can control the inherent variables. Waveform, frequency, size of the electrode, time of contact and cooling periods are some of those considered to be of importance in the studies. On the basis of the research reports, clinical guidelines have been developed to give practical advice to the clinician using electrosurgery. Providing that these safeguards are adhered to, scientific evidence supports the biological compatibility of electrosurgery for intraoral surgical procedures.