Intrapulpal Temperature Increase Research Articles

Temperature changes in the pulp chamber and bleaching gel during tooth bleaching assisted by diode laser (445 nm) using different power settings

The aim of this in vitro study was to investigate the safety of using blue diode laser (445 nm) for tooth bleaching with regard to intrapulpal temperature increase operating at different average power and time settings. Fifty human mandibular incisors (n = 10) were used for evaluating temperature rise inside the pulp chamber and in the bleaching gel during laser-assisted tooth bleaching. The change in temperature was recorded using K thermocouples for the five experimental groups (without laser, 0.5, 1, 1.5 and 2 W) at each point of time (0, 10, 20, 30, 40, 50 and 60 s). As the average power of the diode laser increases, the temperature inside the pulp chamber also increases and that of the bleaching gel was significantly higher in all the experimental groups (p < 0.05). However, the intrapulpal temperature rise was below the threshold for irreversible thermal damage of the pulp (5.6 °C). Average power of a diode laser (445 nm) ranging between 0.5–2 W and irradiation time between 10–60 s should be considered safe regarding the pulp health when a red-colored bleaching gel is used. Clinical studies should confirm the safety and effectiveness of such tooth bleaching treatments. The outcomes of the present study could be a useful guide for dental clinicians, who utilize diode lasers (445 nm) for in-office tooth bleaching treatments in order to select appropriate power parameters and duration of laser irradiation without jeopardizing the safety of the pulp.

Effect Of Different Curing Times Of Composite Resin And Glass Ionomer Liner Use On The Pulpal Temperature

Aim: The present study was performed to measure intrapulpal temperature when photoirradiation of composite resin and glass ionomer liner at different curing times.&#x0D; Material and Methods: Thermocouple (TC) was placed in the intrapulpal space of an extracted human mandibular premolar which had a ClassV cavity preparation (1.5mm dentin thickness remaining on the buccal surface), and restored with composite resin" a bulk fill "and with LED unit " a high-intensity " at different photoirradiation times (10, 20. &amp; 40sec). A temperature increase was obtained during photo-irradiation.&#x0D; Result: The Rise in intrapulpal temperature was associated with an increase in photo-irradiation times and significant in each study groups (p&lt;0.05).&#x0D; Conclusion: intrapulpal temperature increase was attributed to photo-irradiation's time of composite resin. However, temperature's increase during polymerization were below the critical value.

Effectiveness of Two Intensity Levels of Diode Laser in Debonding Metallic Brackets Regarding Enamel Surface Integrity and Pulpal Temperature: An Ex-Vivo Study.

The traditional methods of deboning metal brackets exert excessive force, resulting in enamel scratches, fractures, and patient discomfort. The objective of this study was to evaluate the effectiveness of using two intensity levels of a diode laser for debonding metallic orthodontic brackets as an alternative to the conventional debonding method. Sixty intact, extracted human premolar teeth were used in this study, and metal orthodontic brackets were bonded to the buccal surface of these teeth. The teeth were divided into three groups for the experiment: (1) the control group, where conventional bracket debonding was performed using a debonding plier, (2) the first experimental group, where a diode laser (2.5W, 980nm) was utilized for laser debonding, and (3) the second experimental group, where a diode laser (5W, 980nm) was used for laser debonding. The laser was applied using a sweeping movement for 5 seconds. After debonding, the adhesive remnant index (ARI), the lengths, and the frequency of enamel cracks were compared among the groups. Additionally, an increase in intra-pulpal temperature was measured. In all groups, there were no instances of enamel fractures. Laser debonding resulted in a significant reduction in both the frequency and length of newly formed enamel cracks compared to the conventional debonding method. The laser debonding group exhibited increases in intra-pulpal temperature of 2.37°C and 3.60°C in the second and third groups, respectively. These temperature increases were significantly lower than the threshold of 5.5°C. There were no significant differences observed in the ARI scores among the groups. With all debonding methods, an increase in the length and frequency of enamel cracks should be anticipated. However, laser-assisted debonding of metal brackets offers the advantage of reducing the risk of enamel damage while avoiding thermal damage to the pulp.

New aerosol-decreasing dental handpiece functions sufficiently decrease pulp temperature: An in vitro study.

To assess the changes in intrapulpal temperature between electric high-speed handpieces of different coolant functions ('Water Jet' and 'Water Spray'), coolant port designs (1- and 4-port), suction use, and bur and tooth types using an experimental in vitro setup. Forty-four extracted anterior and posterior teeth were collected. A total of 18 groove cuts (n = 18/coolant port spray design, bur and tooth type group) and 12 groove cuts (n=12/tooth type and suction use) were completed, with a total of 264 groove cuts. Real-time temperature and duration were recorded at 1-s intervals throughout the preparation process using a thermocouple and digital data logger setup (GFX Data Logger Series and EL USB-TC; Lascar Electronics Inc., USA), and the data retrieved using EasyLog Software (EasyLog USB; Lascar Electronics Inc., USA). Statistical analysis was performed (SPSS V.27) for the change in temperature using the analysis of variance and post hoc analysis. The majority of the specimen cuts, regardless of tooth (anterior or posterior) and bur (diamond or carbide) types, handpiece coolant port design, and suction use showed an overall decreasing trend in intrapulpal temperature. No cuts caused a mean temperature change that reached the critical temperature of 42.5°C or resulted in an overall increase in intrapulpal temperature when the 60-s duration was completed. The tested electric handpieces efficiently reduced intrapulpal temperature, with the majority displaying a decreasing trend. A greater decrease in intrapulpal temperature was observed in canines compared to premolars; carbide burs compared to diamond; and with no suction preparations compared to when suction was used.

Effect Of Different Curing Times Of Composite Resin And Glass Ionomer Liner Use On The Pulpal Temperature

&#x0D; Aim: The present study was performed to measure intrapulpal temperature when photoirradiation of composite resin and glass ionomer liner at different curing times.&#x0D; Material and Methods: Thermocouple (TC) was placed in the intrapulpal space of an extracted human mandibular premolar which had a ClassV cavity preparation (1.5mm dentin thickness remaining on the buccal surface), and restored with composite resin" a bulk fill "and with LED unit " a high-intensity " at different photoirradiation times (10, 20. &amp; 40sec). A temperature increase was obtained during photo-irradiation.&#x0D; Result: The Rise in intrapulpal temperature was associated with an increase in photo-irradiation times and significant in each study groups (p&lt;0.05).&#x0D; Conclusion: intrapulpal temperature increase was attributed to photo-irradiation's time of composite resin. However, temperature's increase during polymerization were below the critical value.&#x0D;

Debonding of Leucite-reinforced Glass-ceramic Veneers Using Er, Cr:YSGG Laser Device: Optimizing Speed with Thermal Safety.

Removing laminate veneers on anterior teeth by using an Er,Cr:YSGG dental laser can be completed faster than previously reported while maintaining thermal safety.

Temperatures in the pulpal cavity during orthodontic bonding using an LED light curing unit : An in vitro pilot study.

During bracket bonding, patients often report about thermosensitivity. The reason could be that modern light emitting diode (LED) light curing units run with intensities up to 3200 mW/cm2. In this in vitro pilot studywith nonpulpal circulation approaches, the temperatures in the pulpal cavity were measured. The study included 60extracted teeth divided into four equal groups: lower and upper incisors, premolars and molars. Starting at 37 °C (body temperature) as the reference, the temperature increase was measured for the first series on each tooth without a bracket, without and with arecommended hygienic barrier case for the LED light curing unit, and exposition to light once versus twice. The distance between the tooth and light curing unit was 3 mm. In the second test series, ametal bracket was also bonded to each tooth. In the third series, the light exposition distance was increased to 4 mm. In all three test series, significant intrapulpal temperature increase was found: The highest temperatures were recorded after exposure to light once without the hygienic barrier case. In the first test series, this approach showed temperatures even higher than 42.5 °C in the lower incisors (average 42.99 ± 2.23 °C) and premolars (average 42.94 ± 2.15 °C). Significant increases in the temperature of the pulpal cavity (up to 42.5 °C) may occur during bonding brackets according to the manufacturer's recommendation with an LED light curing unit with in vitro nonpulpal circulation approaches. Therefore it could be reasonable to critically question the recommendation of the manufacturer.

The effect of current pulp capping materials against intrapulpal temperature increase in primary teeth. An in-vitro study by pulpal microcirculation simulation model

Background/purposeWidespread use of light-cured materials has raised the issue of possible thermal effects on pulp tissue. It was aimed to investigate the effectiveness of pulp capping materials (PCM) against intrapulpal temperature increases (ITI) in primary teeth during light-curing of compomers in this study. Materials and methodsA Class-I cavity was prepared on the primary mandibular second molar tooth. An experimental mechanism was used for pulpal microcirculation and temperature regulation of the tooth. There are eight groups in the study: in Groups 1–6: MTA-Angelus, Biodentine, TheraCal LC, Dycal, conventional Glass Ionomer Cement (GIC) and resin-modified GIC were used as PCM, respectively. In Group-7 no PCM was used. In Group-8 only light was applied to the cavity without any PCM or compomer. Compomer restorations were applied in Groups 1–7 with the same material (Dyract XP, DENTSPLY, Weybridge, UK) and light cured for 10sec with the same light-curing unit (Kerr, Demi Plus, 1200 mW/cm2). Temperature changes (Δt) in the pulp chamber were measured and statistically analysed with Kruskal–Wallis and Mann Whitney U tests. ResultsThe highest Δt-value (4.57 ± 0.11 °C) was measured in Group-4 and 7. The lowest Δt-value (3.94 ± 0.4 °C) was measured in Group-8. Δt-values measured in the Groups 2, 3 and 6 were significantly lower than the values measured in Group-4 and 7 (p = 0.001). ITI during the light-curing of the PCM used in Group-3 and 6 exceeded the critical value (5.5 °C) reported in the literature. ConclusionIn protecting the pulp from the harmful thermal effects of restorative procedures Biodentine which is a self-cured material, may be most acceptable choice as an indirect PCM.

Debonding Time and Dental Pulp Temperature With the Er, Cr: YSGG Laser for Debonding Feldespathic and Lithium Disilicate Veneers.

Introduction: The removal of ceramic veneers is a time-consuming procedure in a dental office. Little research has been done in alternative removal techniques for ceramic veneers. The objective of this study was to evaluate the removal of feldspathic and lithium disilicate reinforced glass ceramic veneers by Er, Cr: YSGG and to measure debonding time and pulpal temperature increase during veneer removal. Methods: Fifty-seven bovine incisor teeth were prepared and divided into 3 groups. Ceramic specimens with a thickness of 0.7mm, a width of 4mm and a length of 8 mm were fabricated from feldspathic ceramic, lithium disilicate reinforced glass ceramic HT (high translucency) and lithium disilicate reinforced glass ceramic MO (medium opacity) (19 for each group). Specimens were cemented on the labial surface of incisors using resin cement. The Er, Cr: YSGG laser was applied to each specimen at 2.5 W and 25 Hz. Debonding time was measured for each specimen, and the intrapulpal temperature was detected in 3 specimens for each group. Data were analyzed via one-way analysis of variance (ANOVA) at significance level of 0.05 (α = 0.05). Results: Mean debonding time was 103.68 (26.76), 106.58 (47.22) and 103.84 (32.90) seconds for feldspathic, lithium disilicate MO, and lithium disilicate HT respectively. There was no significant statistical difference among the groups (P value = 0.96). The intrapulpal temperature increase was less than 1°C in all groups. Conclusion: Er, Cr: YSGG can successfully be used to efficiently debond feldspathic and lithium disilicate reinforced glass ceramic veneers. There was no significant difference for debonding time among these ceramic materials. During ceramic laminate veneer removal by laser irradiation, no irritating temperature rise was detected.

Effect of preheated bulk-fill composite temperature on intrapulpal temperature increase in vitro.

The aim of study is measurement of in vitro intrapulpal temperature increase when placing room temperature or preheated (54°C and 60°C) bulk-fill composite. Extracted human lower third molars were selected and class II (MOD) cavities in each tooth were prepared, resulting in a remaining dentin thickness of 1 mm. A K-type thermocouple was placed inside the pulp chamber. Teeth were placed in a 37°C bath, which simulated human body temperature. Teeth were restored with a bulk-fill composite that was stored at room temperature and preheated at 54°C and 60°C. Data were subjected to two-factor mixed-design analysis of variance using a general linear model procedure for repeated measurements. Stage, composite temperature, and stage-composite temperature interaction significantly affected the intrapulpal temperature values (P < .001). Preheating does not represent significant problems in terms of intrapulpal temperature increase. Even Though the preheating process results in an increase in intrapulpal temperature, this temperature increase is not the critical factor that causes harm to the pulp. Preheating can improve material features. Benefits of improved material features are desirable to practitioners. Temperature increase is not the critical factor that harms to the pulp even if the preheating process can result with an increase in intrapulpal temperature.

Different modes of diode laser irradiation: effects on enamel surface and intrapulpal temperature at debonding.

laser aided debonding of ceramic brackets has been proved to be effective in reducing enamel surface damages, though the optimal parameters of laser to be chose is in question. The aim of this study was to investigate the six different regimens of diode laser irradiation on enamel surface characteristics and intrapulpal temperature changes while debonding. 90 polycrystalline brackets were bonded to 90 intact extracted premolars. At debonding, teeth were divided into 6 groups (n = 15) and were subjected to the following regimen of diode laser irradiation; G1 = 2 W, continuous wave, G2 = 2.5 W, continuous wave, G3 = 3 W, continuous wave, G4 = 2 W, pulsed mode, G5 = 2.5 W, pulsed mode, G6 = 3 W, pulsed mode. After debonding, the adhesive remnant index, the lengths and frequency of enamel cracks were compared among the groups. 5 teeth out of 15 were randomly selected from each group to assess the intrapulpal temperature changes. The number of enamel cracks increased significantly in all the specimens after debonding. Enamel crack length increased significantly in all the study groups except G3 and G6. The increase in intrapulpal temperature was significantly below the benchmark of 5.5 C for all the specimens. Significant difference was observed in adhesive remnant index scores among the groups and more than half of the teeth showed a score of 2. Diode-laser irradiation in pulsed mode or continuous wave at given outputs (2, 2.5, 3 W) were not statistically different in regard to producing enamel surface damages or increasing intrapulpal temperature.

Influence of Cavity Preparation, Light-curing Units, and Composite Filling on Intrapulpal Temperature Increase in an In Vitro Tooth Model

This study examined the effect of both the tooth substance and restorative filling materials on the increase in pulp chamber temperature when using light-curing units with different power densities. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of a maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. Polyethylene tubes were connected from the metal tubes to a pump to control the flow rate. For the unprepared tooth group (group 1), the tooth was light-cured from the buccal side using two light-curing units (three curing modes): the VIP Junior (QTH, BISCO, Schaumburg, IL, USA) and the Bluephase LED light-curing units (two modes: LEDlow and LEDhigh; Ivoclar Vivadent, Schaan, Liechtenstein). The power densities of each light-curing unit for the LEDlow, QTH, and LEDhigh modes were 785 mW/cm(2), 891 mW/cm(2), and 1447 mW/cm(2), respectively. All light-curing units were activated for 60 seconds. For the prepared tooth group (group 2), a Class V cavity, 4.0 mm in width by 4.0 mm in height by 1.8 mm in depth in size, was prepared on the buccal surface of the same tooth for the temperature measurement. The light-curing and temperature measurements were performed using the same methods used in group 1. The cavity prepared in group 2 was filled with a resin composite (Tetric N Ceram A3 shade, Ivoclar Vivadent) (group 3) or a flowable composite (Tetric N Flow with A3 shade, Ivoclar Vivadent) (group 4). The light-curing and temperature measurements were performed for these groups using the same methods used for the other groups. The highest intrapulpal temperature (TMAX) was measured, and a comparison was conducted between the groups using two-way analysis of variance with a post hoc Tukey test at the 95% confidence level. The TMAX values were as follows: 38.4°C (group 1), 39.0°C (group 2), 39.8°C (group 3), and 40.3°C (group 4) for the LEDlow mode. For the QTH mode, the TMAX values were 40.1°C (group 1), 40.4°C (group 2), 40.9°C (group 3), and 41.4°C (group 4). For the LEDhigh mode, the TMAX values were 43.3°C (group 1), 44.5°C (group 2), 44.7°C (group 3), and 45.3°C (group 4). The statistical analysis revealed the following: the TMAX values were arranged by mode in the following manner: LEDlow < QTH < LEDhigh (p<0.05) and group 1 < group 2 ≤ group 3 ≤ group 4 (p<0.05).

Does ultra-pulse CO2 laser reduce the risk of enamel damage during debonding of ceramic brackets?

This study seeks to evaluate the enamel surface characteristics of teeth after debonding of ceramic brackets with or without laser light. Eighty premolars were bonded with either of the chemically retained or the mechanically retained ceramic brackets and later debonded conventionally or through a CO(2) laser (188W, 400Hz). The laser was applied for 5 s with scanning movement. After debonding, the adhesive remnant index (ARI), the incidence of bracket and enamel fracture, and the lengths, frequency, and directions of enamel cracks were compared among the groups. The increase in intrapulpal temperature was measured in ten extra specimens. The data were analyzed with SPSS software. There was one case of enamel fracture in the chemical retention/conventional debonding group. When brackets were removed with pliers, incidences of bracket fracture were 45% for the chemical retention, and 15% for the mechanical retention brackets. No case of enamel or bracket fracture was seen in the laser-debonded teeth. A significant difference was observed in ARI scores among the groups. Laser debonding caused a significant decrease in the frequency of enamel cracks, compared to conventional debonding. The increase in intrapulpal temperatures was below the benchmark of 5.5 °C for all the specimens. Laser-assisted debonding of ceramic brackets could reduce the risk of enamel damage and bracket fracture, and produce the more desirable ARI scores without causing thermal damage to the pulp. However, some augmentations in the length and frequency of enamel cracks should be expected with all debonding methods.

Dentine caries inhibition through CO2 laser (10.6 μm) irradiation and fluoride application, in vitro

ObjectiveThe purpose of the study was to investigate whether dentine irradiation with a pulsed CO2 laser (10.6μm) emitting pulses of 10ms is capable of reducing dentine calcium and phosphorus losses in an artificial caries model. DesignThe 90 dentine slabs obtained from bovine teeth were randomly divided into six groups (n=15): negative control group (GC); positive control group, treated with fluoride 1.23% (GF); and laser groups irradiated with 8J/cm2 (L8); irradiated as in L8+fluoride 1.23% (L8F); irradiated with 11J/cm2 (L11); irradiated as in L11+fluoride 1.23% (L11F). After laser irradiation the samples were submitted to a pH-cycling model for 9 days. The calcium and phosphorous contents in the de- and remineralization solutions were measured by means of inductively coupled plasma optical emission spectrometer – ICP-OES. Additionally intrapulpal temperature measurements were performed. The obtained data were analysed by means of ANOVA and Tukey's test (α=0.05). ResultsIn the demineralization solutions the groups L11F and GF presented significantly lower means of calcium and phosphorous losses than the control group; and in L11F means were significantly lower than in the fluoride group. Both irradiation parameters tested caused intrapulpal temperature increase below 2°C. ConclusionIt can be concluded that under the conditions of this study, CO2 laser irradiation (10.6μm) with 11J/cm2 (540mJ and 10Hz) of fluoride treated dentine surfaces decreases the loss of calcium and phosphorous in the demineralization process and does not cause excessive temperature increase inside the pulp chamber.

Pulpal temperature increase with high-speed handpiece, Er:YAG laser and ultrasound tips

The aim of this study was to compare intrapulpal temperature increase produced by high-speed handpiece, Er:YAG laser and CVDentus ultrasound tips during cavity preparation. Thirty bovine mandibular incisors with an enamel/dentin thickness of 4 mm at buccal surface had their roots amputated and were allocated to the following groups (n=10): Group I- high-speed handpiece; Group II- noncontact Er:YAG laser (250 mJ/4Hz); and Group III- CVDentus ultrasouns tips. All devices were used with water cooling. Class V cavities were prepared to a depth of 3.5 mm, measured with a periodontal probe. A type T thermocouple was placed inside the pulp chamber to determine the temperature increase (°C), which was recorded by a data acquisition system ADS 2000 IP (Lynx Technology) linked to a notebook computer. Data were analyzed statistically by oneway ANOVA and Tukey's test (p=0.05). The mean temperature rises were: 1.10°C (±0.56) for Group I, 0.84°C (±0.55) for Group II, and 3.00°C (± 1.34) for Group III. There were no statistically significant differences (p>0.05) between Groups I and II, but both of them differed significantly from Group III (p<0.05). In conclusion, the use of Er:YAG laser and high-speed handpiece for cavity preparation resulted in similar temperature increase. Although ultrasound tips generated significantly higher intrapulpal temperature increase, it remained below the critical value of 5.5°C and may be considered safe for use.

Intrapupal temperature variation during Er,Cr: YSGG enamel irradiation on carries prevention

Studies have shown the cariostatic effect of Er,Cr:YSGG (2.78 μm) laser irradiation on human enamel and have suggested its use on caries prevention. However there are still no reports on the intrapulpal temperature increase during enamel irradiation using parameters for caries prevention. The aim of this in vitro study was to evaluate the temperature variation in the pulp chamber during human enamel irradiation with Er,Cr:YSGG laser at different energy densities. Fifteen enamel blocks obtained from third molars (3 x 3 x 3 mm) were randomly assigned to 3 groups (n=5): G1 – Er,Cr:YSGG laser 0.25 W, 20 Hz, 2.84 J/cm2, G2 – Er,Cr:YSGG laser 0.50 W, 20 Hz, 5.68 J/cm2, G3 – Er,Cr:YSGG laser 0.75 W, 20 Hz, 8.52 J/cm2. During enamel irradiation, two thermocouples were fixed in the inner surface of the specimens and a thermal conducting paste was used. One-way ANOVA did not show statistically significant difference among the experimental groups (α=0.05). There was intrapulpal temperature variation ≤0.1°C for all irradiation parameters. In conclusion, under the tested conditions, the use of Er,Cr:YSGG laser with parameters set for caries prevention lead to an acceptable temperature increase in the pulp chamber.

Temperature rise during orthodontic bonding with various light-curing units--an in vitro study.

The purpose of this in vitro study was to investigate the temperature changes in the pulp chamber during bracket bonding using three different light sources. Bracket bonding was performed on one lower first premolar and one lower central incisor at two different distances (surface and 10 mm). The measurements were taken with a J-type thermocouple wire, placed in the pulp chamber and connected to a data logger. Analysis of variance revealed that pulp chamber temperature changes were influenced by the light source, the tooth type, and the distance from the tip of the light guide to the bracket surface. Halogen induced significantly higher intrapulpal temperature changes than light-emitting diode and Xenon Plasma Arc (PAC) (P = .000). The temperature increase was significantly higher when the light-guide tip was positioned at the surface of the teeth than at the 10-mm distance with all light-curing units (P = .000). All light-curing units produced higher intrapulpal temperature increase in the mandibular incisor than in the premolar. Power PAC produced significantly higher heat changes in the incisor than in the premolar. Orthodontic bonding with different light-curing units did not exceed the critical 5.5 degrees C value for pulpal health.

Surface and intra-pulpal temperature rises during tooth bleaching: an in vitro study

To measure the surface and intra-pulpal temperature increases in vitro on upper and lower anterior teeth during tooth whitening procedures. A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Intra-pulpal temperature readings were made on upper and lower central incisors, lateral incisors and canines. Four lamps recommended for tooth bleaching were tested; a plasma arc lamp, a xenon-halogen lamp, a standard halogen lamp and a diode laser lamp. Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. The increase in surface temperature readings ranged from 0.44 degrees C (luma arch) to 86.3 degrees C (laser) with no bleaching gel present. Intra-pulpal temperature increases ranged from 0.30 degrees C to 15.96 degrees C. The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. The increase in the intrapulpal temperature with most bleaching lamps was below the critical threshold of a 5.50 degrees C increase thought to produce irreversible pulpal damage. The only lamp that produced an intrapulpal temperature increase above this threshold was the laser-based lamp and caution is advised when using this equipment.

Intra-pulpal temperature rises in power bleaching

Objective To measure the surface and intra-pulpal temperature increases in vitro on upper and lower anterior teeth during tooth whitening procedures. Method A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Intra-pulpal temperature readings were made on upper and lower central incisors, lateral incisors and canines. Four lamps recommended for tooth bleaching were tested; a plasma arc lamp, a xenon-halogen lamp, a standard halogen lamp and a diode laser lamp. Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. Results The increase in surface temperature readings ranged from 0.44°C (luma arc) to 86.3°C (laser) with no bleaching gel present. Intra-pulpal temperature increases ranged from 0.30°C to 15.96°C. The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. Conclusions The increase in the intrapulpal temperature with most bleaching lamps was below the critical threshold of a 5.50°C increase thought to produce irreversible pulpal damage. The only lamp that produced an intrapulpal temperature increase above this threshold was the laser-based lamp and caution is advised when using this equipment.

Effect of light-enhanced bleaching on in vitro surface and intrapulpal temperature rise.

This study investigated the effect of the presence, absence, and aging of a heat-enhancing compound (colorant) added to bleaching gel on the temperature rise of the gel itself, as well as the temperature rise within the pulp chamber, when a tooth was exposed to a variety of light-curing units in vitro. An extracted human upper central incisor was fitted with thermocouples placed in the pulp chamber as well as on the facial tooth surface. A temperature-controlled simulated intrapulpal fluid flow was provided to the tooth, and bleaching agent (Opalesence XTRA, Ultradent) containing heat-enhancing colorant, aged colorant, or no colorant was applied to the facial surface. The tooth and light-curing unit were placed in a thermostatically controlled oven at 37 degrees C, and real-time gel and intrapulpal temperature values were recorded digitally. Light-curing units used were a plasma arc light (PAC) (PowerPac, ADT), a conventional quartz tungsten halogen source (QTH) (Optilux 501, Demetron/Kerr), the QTH light used in high-power (bleaching) mode, and an argon ion laser (AccuCure 3000, LaserMed). An exposure scenario simulating light-enhanced bleaching of 10 upper teeth was developed. Temperature rise over the pre-exposure, baseline value associated with the last light exposure in the bleaching sequence was calculated for each curing and bleaching combination. Five replications for each test condition were made. Temperature rise values were compared using analysis of variance (ANOVA) at a preset alpha of 0.05. When fresh colorant-containing bleach was used, the PAC light increased bleach temperature 39.3 degrees C above baseline. With no added colorant, temperature rise was 37.1 degrees C. The QTH light in bleach mode resulted in gel temperature 24.8 degrees C above baseline, whereas the temperature increase was only 11.5 degrees C when no colorant was used. Conventional QTH light use increased fresh bleach temperature by 17.7 degrees C, whereas an increase of only 11.1 degrees C was measured without colorant. The argon ion laser produced equivalent temperature rise regardless of the presence or freshness of the colorant, approximately 9.4 degrees C. Intrapulpal temperatures were all significantly lower than those recorded in the bleaching gel and ranged from 5 degrees to 8 degrees C. As a rule, the presence of fresh heat-enhancing colorant in the bleaching gel resulted in a significant intrapulpal temperature increase (approximately 1 degrees C) over that reached using other lights. The PAC and the QTH light used in bleach mode induced greater intrapulpal temperature rise than the laser. Freshness of bleaching agent incorporating light-activated, heat-enhancing colorant influences temperature rise of bleaching gel and also may increase intrapulpal temperature values. Use of intense lights does elevate bleach temperature and also results in increased intrapulpal temperature that may further impact on patient sensitivity and pulpal health resulting from this treatment.