Title Laser Activated Teeth Whitening Systems May Cause a Greater Rise in Intrapulpal Temperature Compared to Other Heat-Activated Bleaching Techniques, Potentially Resulting in Pulpal Damage
Clinical Question In an adult patient undergoing an in-office external bleaching procedure, what heat-activated bleaching mechanism causes a greater rise in intrapulpal temperature?
Clinical Bottom Line Laser activated external bleaching caused the greatest rise in intrapulpal temperature. This is supported by a systematic review of several in vitro studies in which most studies proved laser activation to show the highest rise in pulp temperature. This is further supported by an in vitro study on extracted molars. Thus, it is recommended that laser activated whitening systems be used with caution and according to manufacturer instructions to limit pulpal response.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
16820199Buchalla/ 200617 studiesSystematic review of non-randomized trials
Key resultsIn the systematic review (Buchalla 2006) 17 studies were evaluated which compared heat activated and non-activated bleaching treatments. Seven of these studies specifically addressed the topic of temperature increase in pulpal dentin due to various heat activation modes. The majority of these studies found that laser activation caused the highest temperature increase, as opposed to other heat sources such as halogen lamps, infrared light, and plasma arc lamps. In some cases, the temperature rise exceeded the critical threshold of 5.5 degrees Celsius as cited in the literature. This threshold was determined to be associated with irreversible pulpal damage. Only one study found that the plasma arc lamp and halogen lamp led to highest rise in pulpal temperature. Based on the majority of the outcomes, heat activation, specifically laser activated whitening therapies can potentially cause pulpal irritation and even potential pulpal damage. Thus, laser activated systems should be used with caution and according to manufacturer instructions.
19936522Michida/200924 extracted human molarsin vitro study
Key resultsIn this study (Michida, 2009) halogen and Nd:YAG laser use resulted in significantly higher intrapulpal temperature variation than no light activation and activation by LED (p<.05). The results from no light activation and LED light activation appeared similar with regards to intrapulpal temperature variation (p<.05). Specifically, 24 molars were sectioned into 48 specimens that were divided into 4 groups of 12 specimens. Each group received a different treatment. Group one was the control receiving no light activation, group two received halogen light activation, group three received LED light activation and group four received laser light activation. The maximum intrapulpal temperature variation was 6.9, 1.7, 2.9, and 1.5 degrees celsius for Groups 4, 3, 2 and 1 respectively (refer to comments on Evidence section for Group descriptions). Michida referenced other studies which have shown that initial reversible histologic alterations begin with a temperature variation of 3.3 degrees Celsius. These studies further stated that a rise of 5.5 degrees Celsius results in odontoblastic damage, and tissue alterations and pulp necrosis begin at approximately a 6.9 degrees Celsius rise in pulpal temperature. The study showed that Nd:YAG laser activation could potentially lead to pulpal necrosis. Halogen light activation did not have a very significant rise in intrapulpal temperature, and LED light activation was close to the same in pulpal temperature rise as no light activation. Extrapolating to an in vivo study, it should be noted that a thicker dentin could aid in protection of the pulp from temperature variation. Furthermore, inflammatory infiltrate in an intact blood flow could act as a heat sink, relieving the heat which normally causes some expansion of liquid within dentinal tubules that cause hypersensitivity.
Evidence Search bleaching[All Fields] AND (("light"[MeSH Terms] OR "light"[All Fields]) AND activation[All Fields]) AND systematic[sb] intrapulpal[All Fields] AND ("temperature"[MeSH Terms] OR "temperature"[All Fields] OR "body temperature"[MeSH Terms] OR ("body"[All Fields] AND "temperature"[All Fields]) OR "body temperature"[All Fields]) AND bleaching[All Fields]
Comments on
The Evidence
Validity: Buchalla (2006) performed a systematic review of 17 studies comparing various heat-activated mechanisms of tooth whitening. The authors completed a comprehensive search for relevant studies that included light activated whitening systems. Several of these studies included results of temperature effects in addition to efficacy. The studies that addressed pulpal temperature rise were performed in vitro, as currently there are no in vivo trials. Three of these studies found the same conclusion that lasers caused greater temperature rise in the pulp, yet one of these studies found that plasma arc lamp and halogen lamps caused the greatest temperature rise. No meta-analysis was performed and no statistical data regarding the evidence was provided. Majority of these studies included only incisors. Michida (2009) performed a laboratory study where 24 molar teeth were sectioned into 48 specimens. These specimens were randomly divided into four groups of 12. Each group received a different treatment. Group one was the control receiving no light activation, group two received halogen light activation, group three received LED light activation and Group four received Laser light activation. The specimens were similar to start with and all received similar treatment, except for the light source utilized. There was no evidence of bias or competing interests. Perspective: I do not support the use of heat activation of bleaching gels for in-office external bleaching, because most studies show that heat activation does not improve bleaching results, but can potentially result in irreversible pulpal damage.
Applicability Assessment of patient representation needs to be evaluated with further trials in vivo. All light activation treatments can be easily performed in a general dentistry office on healthy adult patients interested in teeth whitening procedures. Patients may experience discomfort and sensitivity due to treatment and are at a possible risk of pulpal damage based on light activation mechanism utilized. Consideration and careful choice/implementation of various light activating mechanisms for whitening treatments can lower the risk of patient sensitivity, discomfort, and possible pulpal necrosis.
Specialty (General Dentistry)
Keywords Teeth Whitening, Whitening, Laser Activated Whitening, Light Activated Whitening, Bleaching, Pulpal Temperature Rise
ID# 2638
Date of submission 02/24/2014
E-mail szozda@livemail.uthscsa.ed
Author Katarzyna Szozda
Co-author(s) e-mail
Faculty mentor Joseph Bartoloni, DMD
Faculty mentor e-mail Bartoloni@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available