Temperature Increase In Pulp Chamber Research Articles

How does indirect air-cooling influence pulp chamber temperature in different volume teeth and absence/presence of resin-based composite during light curing?

BackgroundLight-curing of materials during restorative dental procedures poses a risk for pulp tissue overheating. Therefore, the aim of this study was to investigate the effect of indirect air-cooling on pulp chamber temperatures during light-curing of varying volume teeth and absence/presence of resin-based composite (RBC) at different exposure time.MethodsThe volume of 11 human teeth was measured by micro computed tomograph. An experimental rig controlled the thermal environment of the teeth and a thermocouple inserted retrograde into the root canal measured temperature changes. Pulp chamber temperature was measured with and without air-cooling on teeth without and with RBC at 15 s, 30 s and 60 s intervals. Generalized estimating equations were used for statistical analysis.ResultsThe temperature increase with air-cooling (versus no air-cooling) was lower in teeth despite absence/presence of RBC (β = − 4.26, 95%CI − 5.33 and β = − 4.47, 95%CI − 5.60, respectively). With air-cooling, the temperature increase in teeth with RBC was lower compared to teeth without RBC (β = − 0.42, 95%CI -0.79; − 0.05). Higher teeth volume resulted in lower temperature increase with air-cooling than without air-cooling (β = − 0.04, 95%CI -0.07; − 0.01 and β = − 0.17, 95%CI -0.30; − 0.05, respectively).ConclusionsAir-cooling resulted in lower pulp chamber temperature increase. Using air-cooling, the temperature increase was lower in teeth with RBC compared to teeth without RBC. Lower volume teeth resulted in higher temperature increase, thus they seemed to benefit more from air-cooling compared to higher volume teeth. Air-cooling could be an effective tool in controlling pulp temperature increase during light-curing, especially when the tooth volume is small.

Light-curing units used in dentistry: Effect of their characteristics on temperature development in teeth.

This study aimed to investigate pulp chamber and surface temperature development using different LED light curing units (LCUs). Eight brands of LED-LCUs were tested in a laboratory bench model. The pulp chamber and surface temperature were recorded with a type T thermocouple and infrared cameras, respectively. The highest pulp chamber and surface temperature increase was 6.1±0.3°C and 20.1±1.7°C, respectively. Wide-spectrum LED-LCUs produced higher pulp chamber temperature increase at 0 mm and 2 mm but lower at 4 mm. Narrow-spectrum LED-LCUs produced higher surface temperature increase. LED-LCU featuring modulated output mode resulted in lower increase in pulp chamber temperature but higher on surface temperature. LED-LCU with light guide tip delivering an inhomogeneous beam caused higher increase in temperature on the surface and in the pulp chamber. LED-LCUs with different spectral emission, output mode and light guide tip design contributed to different temperature development in the pulp chamber and at the surface of teeth.

Pulp chamber temperature variation evaluation using fiber Bragg grating sensor.

The present in vitro study proposes a novel (to the best of our knowledge) methodology employing a fiber Bragg grating sensor for the evaluation of pulp chamber temperature increase during the polymerization of the composite resin induced by the light-curing process. A fiber Bragg grating temperature sensor (FBGTS) has been developed in view of its ease of insertion into the pulp chamber with minimal widening of the pulpal canal. The temperature increase in the pulpal chamber during the polymerization of the composite resin by light curing has been characterized with varying depths of cavities of 1 mm, 1.5 mm, and 2 mm employing FBGTS. Also, the increase in temperature of the pulpal chamber during the polymerization of the composite resin has been studied with variants of the light-curing device. The obtained results are expected to be an indicator towards the potential hazard caused by heat induced pulpal injuries during the polymerization of composite resins using a light-curing device.

Comparative study of intrapulpal temperature stress during Er,Cr:YSGG-supported dental bleaching versus conventional dental power bleaching. An in vitro study

The purpose of this in vitro study was to evaluate the safety of the Er,Cr:YSGG bleaching treatment in terms of pulp chamber temperature increase in teeth, as well as to test two different bleaching gels applied in the same procedure. Our previously published pilot study suggested that the most susceptible teeth during Er,Cr:YSGG-supported bleaching are the maxillary lateral incisors and mandibular incisors. These two types of teeth were used in order to assess the safety of the procedure with regard to tooth vitality. For the needs of this study, 60 teeth were tested (30 maxillary lateral incisors (TT1) and 30 mandibular incisors (TT2)). The experimental procedure involved the use of an Er,Cr:YSGG laser (2780 nm, Waterlase MD, Biolase, USA) with two different bleaching gels. A yellow-colored bleaching agent, with a concentration of 38% H2O2 (Power whitening, WHITEsmile GmbH, Germany) (BG 1), and a purple-colored agent for in-office tooth whitening, with a concentration of 35% H2O2 (Laser-White20, Biolase) (BG 2), were utilized in the experiment. The tip employed was a 6-mm-long Z-type glass tip (MZ8) of 800 μm diameter. As to the applied power settings, the average output power was set at 1.25 W and the pulse duration at 700 μs (S-mode), while the pulse repetition rate was 10 Hz. The results showed that during Er,Cr:YSGG-supported tooth bleaching, the temperature rise in the pulp chamber did not exceed the temperature threshold of 5.6 °C, regardless of the bleaching gel used (2.03 ± 0.55 °C for BG1 and 1.53 ± 0.48 °C for BG2) and can therefore be considered a safe procedure. Moreover, a time-consistent higher temperature difference was observable during the BG1 application, compared to that of BG2.

Modern high powered led curing lights and their effect on pulp chamber temperature of bulk and incrementally cured composite resin.

Pulpal temperature changes induced by modern high powered light emitting diodes (LEDs) are of concern when used to cure composite resins. This study showed an increase in pulp chamber temperature with an increase in power density for all light cure units (LCU) when used to bulk cure composite resin. Amongst the three LEDs tested, the Elipar Freelight-2 recorded the highest temperature changes. Bulk curing recorded a significantly larger rise in pulp chamber temperature change than incrementally cured resin for all light types except for the Smartligh PS. Both the high powered LED and the conventional curing units can generate heat. Though this temperature rise may not be sufficient to cause irreversible pulpal damage, it would be safer to incrementally cure resins.

Effect of simulated pulpal blood flow rate on the rise in pulp chamber temperature during direct fabrication of exothermic provisional restorations.

To evaluate exvivo the effect of several simulated pulpal blood flow rates on the change in pulp chamber temperature during direct fabrication of a provisional restoration using a polymethylmethacrylate (PMMA) resin. Fifteen noncarious human premolars were prepared for complete coverage restorations. A curved needle connected to a peristaltic pump simulated the pulp blood flow. Two K-type thermocouples connected to a digital thermometer were placed in the pulp chamber, and the assembly was placed in an incubator at 37°C. Three provisional crowns were made for each specimen using no water flow (group 1), a 1-mLmin-1 flow rate (group 2) and a 0.5-mL/min-1 flow rate (group 3). The pulp chamber temperature was recorded continuously during polymerization until the temperature increase peaked and started to decrease and reached the baseline temperature (37°C). The temperature increase was measured for the three water flow conditions. Data were analysed statistically using descriptive statistics, repeated measures one-way analysis of variance (anova) with Greenhouse-Geisser correction and Bonferroni tests. The level of significance was set at P<0.05. All of the groups were associated with an increased pulp chamber temperature. Groups with flow rates at 1 and 0.5mLmin-1 had a significantly lower temperature rise when compared to the group without water flow (P<0.001). Direct fabrication of provisional restorations can cause a critical increase in pulp chamber temperature. However, in the presence of simulated pulpal blood flow rates of 1 or 0.5mLmin-1 , the increase in pulp chamber temperature did not exceed the critical threshold (5.6°C).

Whitening gel and light source influence on pulp chamber temperature

The chemical injury caused to the pulp by the penetration of the whitening gel is already known, but another possible cause may be the heat generated by the irradiation of the whitening gel with light sources to accelerate the whitening reaction. Objective: To evaluate in vitro the temperature increasing in the pulp chamber during in-office bleaching with different gel concentrations and light sources. Material and methods: A maxillary human central incisor was used in the 6 groups evaluated. The specimen was sectioned 3 mm apical to the cementoenamel junction. The root canal and pulp chamber were cleaned and widened with a diamond bur to receive the sensor of a thermocouple thermometer. The following hydrogen peroxide gel concentrations were evaluated: 35%, 25%, 15%, and 10%; and the following light sources were applied: blue hybrid LED/laser and violet hybrid LED/laser. The specimen bleaching was repeated 6 times per group. As a control, the temperature was measured with the application of light, without applying any gel. Results were evaluated with one-way ANOVA and Tukey’s test (α = 5%). Results: Significant differences between groups were observed (p &lt; 0.05). The blue LED without the gel induced the smallest heat (37.5 ± 0.2) and the blue LED with 15% gel caused the highest heat (38.2 ± 0.3). The combination of violet LED with the 10% gel caused no significant increase in temperature compared to the control in which light was used without gel (p&gt; 0.05). Conclusion: No increase in pulp chamber temperature was higher than 2°C.

The effect of bleaching gel and (940nm and 980nm) diode lasers photoactivation on intrapulpal temperature and teeth whitening efficiency.

This invitro study aimed to investigate the whitening efficacy of 940nm and 980nm diode laser photoactivation in tooth bleaching by analysing pulp chamber temperature, as well as the change in tooth colour. Root canals of thirty extracted human lower premolars were prepared. Laserwhite* 20 bleaching agent containing 38% of hydrogen peroxide was photoactivated with 7W output power of 940nm and 980nm diode lasers for 120 s. Bleaching gel reduced 27-29% of the temperature from reaching the pulp chamber. For shade assessment, only the groups photoactivated using diode lasers showed statistically significant differences from control group P<0.001. Within the studied parameters, both 940nm and 980nm diode lasers produced a safe pulp temperature increase. Diode laser photoactivation of bleaching gel resulted in more efficient teeth whitening. Photoactivation with 940nm diode laser yielded the highest change in colour with only minor increase in pulp chamber temperature.

LED Curing Lights and Temperature Changes in Different Tooth Sites.

Objectives. The aim of this in vitro study was to assess thermal changes on tooth tissues during light exposure using two different LED curing units. The hypothesis was that no temperature increase could be detected within the dental pulp during polymerization irrespective of the use of a composite resin or a light-curing unit. Methods. Caries-free human first molars were selected, pulp residues were removed after root resection, and four calibrated type-J thermocouples were positioned. Two LED lamps were tested; temperature measurements were made on intact teeth and on the same tooth during curing of composite restorations. The data was analyzed by one-way analysis of variance (ANOVA), Wilcoxon test, Kruskal-Wallis test, and Pearson's χ 2. After ANOVA, the Bonferroni multiple comparison test was performed. Results. Polymerization data analysis showed that in the pulp chamber temperature increase was higher than that without resin. Starlight PRO, in the same condition of Valo lamp, showed a lower temperature increase in pre- and intrapolymerization. A control group (without composite resin) was evaluated. Significance. Temperature increase during resin curing is a function of the rate of polymerization, due to the exothermic polymerization reaction, the energy from the light unit, and time of exposure.

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).

Erratum

In Operative Dentistry, 2010, 35-3, 308–313, Microleakage in Class II Restorations: Open vs Closed Centripetal Build-up Technique, the correct order of the authors is: A Fabianelli, A Sgarr, C Goracci, A Cantoro, S Pollington &amp; M Ferrari. This update has been posted online.Also in Operative Dentistry, 2010, 35-3, 353–361, Parameters Influencing Increase in Pulp Chamber Temperature with Light-curing Devices: Curing Lights and Pulpal Flow Rates, S-H Park, J-F Roulet &amp; SD Heintze, Figures 1–3 have been updated online.

Parameters Influencing Increase in Pulp Chamber Temperature with Light-curing Devices: Curing Lights and Pulpal Flow Rates

This laboratory study examined the effects of curing lights with different light intensities and changing flow rate on the increase in pulpal temperature during the light curing process and the rate of the subsequent decrease in temperature after the termination of light curing. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of the 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. The tubes were connected to a pump to control the flow rate. The water flow rate was set to 4.2 microl/minute, 28 microl/minute or 70 microl/minute. At each flow rate, the unprepared tooth was light cured from the buccal side 1 mm from the buccalsurface, using four different curing lights. The temperature data were recorded and stored on a computer every second for three minutes. The curing lights that were used were: Astralis 10 (QTH(high), Ivoclar Vivadent), Bluephase 16i (LED(conv), Ivoclar Vivadent) and two experimental LED-curing lights (LED(exp2000), LED(exp3000), Ivoclar Vivadent). The power densities were 1200 mW/cm2, 1600 mW/cm2, 2000 mW/cm2 and 3000 mW/cm2, respectively. The curing lights, LED(conv), LED(exp2000) and LED(exp3000) were activated for 60 seconds, and the QTH(high) was activated for 30 sec- onds. The maximum intrapulpal temperature (TM) and rate of temperature change at 30 seconds after turning off the light (S(30LO)) were analyzed by two-way ANOVA with a post-hoc Tukey test (p < 0.05). The influencing factors were the flow rates and curing lights. The T(MAX) ranged from 41.0 degrees C to 53.5 degrees C. There was a difference between the curing lights (p < 0.05), with LED(exp3000) > LED(exp2000) > LED(conv) > QTH(high). There was no difference in T(MAX) between the different flow rates (p > 0.05). Both the curing lights and flow rates affected the SE(30LO) (p < 0.05). The S(30LO) was LED(exp3000) < LED(exp2000) > LEDon, , QTH(high) (p < 0.05). The S(30LO) at 70 microl/minutes was higher than at 4.2 pd/minutes and 28 microl/minutes (p < 0.05). Because the increase in temperature is directly related to the light intensity and exposure time, curing devices with high power density (> 1200 mW/cm2) should only be activated for a short period of time (< 15 seconds) even in teeth without cavity preparation. The flow rate had only a negligible effect on the temperature increase.

Influence of the degree of dentine mineralization on pulp chamber temperature increase during resin-based composite (RBC) light-activation

Objectives To analyse the influence of the degree of dentine mineralization on the pulp chamber temperature increase during composite light-activation. Methods Dentine discs (2 mm thick) obtained from recently extracted teeth or those with extensive dentine sclerosis were analysed by FT-IR spectrometry in order to choose the two discs with the greatest difference in the degree of mineralization. A model tooth was set up with the dentine discs between a molar with the pulp chamber exposed and a crown with a standardized class II cavity. A K-type thermocouple was introduced into the molar root until it came into contact with the dentine discs and the cavity was filled with P60 resin composite. The temperature rise was measured for 120 s after light-activation began: Standard ( S) 600 mW/cm 2/40 s; Ramp ( R) 0 → 800 mW/cm 2/10 s + 800 mW/cm 2/10 s; Boost ( B) 850 mW/cm 2/10 s and LED ( L) 1.300 mW/cm 2/40 s ( n = 10). The same protocol was repeated after grinding the dentine discs to 1.0 and 0.5 mm thickness. Results The temperature increase was significantly higher in dentine with high degree of mineralization ( p < 0.05). With respect to the dentine thickness, the following result was found: 2 mm < 1 mm < 0.5 mm ( p < 0.05). The light-activation mode also presented significant difference as follows: S > R = L > B ( p < 0.05). Conclusions The higher the degree of dentine mineralization the greater the increase in pulp chamber temperature. The temperature increase was influenced by the light-polymerization mode and dentine thickness.

Surface and pulp chamber temperature rises during tooth bleaching using a diode laser: a study in vitro

To measure the surface and pulp chamber temperature increases in vitro on upper and lower anterior teeth during a tooth whitening procedure using a diode laser. A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Pulp chamber temperature readings were made on upper and lower central incisors, lateral incisors and canines. A diode laser recommended for tooth bleaching was tested at three different power settings (1W, 2W, 3W). Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. The increase in surface temperature readings ranged from 37 degrees C (1W) to 86.3 degrees C (3W) with no bleaching gel present. Pulp chamber temperature increases ranged from 4.3 degrees C (1W) to 16 degrees C (3W). The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. The increase in the pulp chamber temperature with the laser used at 1-2W was below the critical temperature increase of 5.5 degrees C thought to produce irreversible pulpal damage. However, a power setting of 3W produced a pulp chamber temperature increase above this threshold (16 degrees C) and caution is advised when using this setting.

Tooth bleaching using a diode laser

Objective To measure the surface and pulp chamber temperature increases in vitro on upper and lower anterior teeth during a tooth whitening procedure using a diode laser. Method A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Pulp chamber temperature readings were made on upper and lower central incisors, lateral incisors and canines. A diode laser recommended for tooth bleaching was tested at three different power settings (1W, 2W, 3W). 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 37°C (1W) to 86.3°C (3W) with no bleaching gel present. Pulp chamber temperature increases ranged from 4.3°C (1W) to 16°C (3W). The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. Conclusions The increase in the pulp chamber temperature with the laser used at 1-2W was below the critical temperature increase of 5.5°C thought to produce irreversible pulpal damage. However, a power setting of 3W produced a pulp chamber temperature increase above this threshold (16°C) and caution is advised when using this setting.

The effect of dentin desensitizers on thermal changes in the pulp chamber during fabrication of provisional restorations.

The purpose of this study was to evaluate the effect of two dentin desensitizers on the pulp chamber temperature increase during fabrication of provisional restorations by a direct method. Sixty intact extracted mandibular third molars were prepared for a metal-ceramic complete crown. Then the teeth were randomly divided into three groups of 20 each. Group 1, no dentin desensitizer was used as the control group; group 2, a resin-based dentin desensitizer was selected; and group 3, the prepared teeth surfaces were coated with polyurethane cyanoacrylate adhesive. Each of the three groups was further divided into two polymerizing systems (autopolymerizing and a photopolymerizing) of 10 each. After insertion of the resin-filled matrix, the temperature change in the pulpal chamber was recorded with thermocouple connected to a data logger. anova indicated no significant differences for all combinations of desensitizing agents and curing methods (P > 0.05). When light cured composite or chemical curing acrylics were used to make temporary crowns, the presence of desensitizing agent did not reduce the temperature transmitted from the provisional material; the residual temperature rise transmitted was of such a magnitude as to cause concern regarding possible thermal injury to pulp.

In-vitro pulp chamber temperature rise during composite resin polymerization with various light-curing sources

Objectives: The purpose of this in vitro study was to measure the pulp chamber temperature increase induced during composite resin polymerization with various visible light-curing units. Methods: A Class II cavity was prepared in an extracted molar tooth, leaving a dentin layer 1 mm thick between pulp chamber and proximal cavity wall. A 2 mm composite resin layer was applied to the proximal box and light-cured with the selected curing units: Heliolux II (H; 320 mW/cm 2), QHL 75 (Q; 505 mW/cm 2), Astralis 5 (A; 515 mW/cm 2), Optilux 500 (O; 670 mW/cm 2), Elipar Highlight (EH; 730 mW/cm 2), ADT 1000 PAC (P; 1196 mW/cm 2). Light-curing took place for 40 s (H, A, Q, O, EH), 5 and 10 s (P). Measurement of pulp chamber temperature changes (starting temperature: 37.0±0.1°C) during polymerization was performed with a K-type thermocouple positioned at the pulp–dentin junction. Mean values were calculated from 10 measurements with each light-curing unit. ANOVA and Dunnett t-test were used for statistical analyses. Results: Maximum temperature changes varied significantly depending on the light-curing unit used: 2.9±0.3°C (H), 4.7±0.5°C (A), 5.4±0.3°C (P, 5 s), 5.6±0.4°C (Q), 6.1±0.2°C (EH, 2-step mode: 100 mW/cm 2 over 10 s, 730 mW/cm 2 over 30 s), 6.9±0.4°C (EH), 7.3±0.3°C (O), 7.8±0.9°C (P, 10 s). Significance: It is concluded that light-polymerization with curing units characterized by high energy output (A,EH,O,P,Q) causes significantly higher pulp chamber temperature changes as compared to the conventional curing light (H). Therefore, clinicians should be aware of the potential thermal hazard to the pulp which might result from visible-light curing of composite resins.

Tooth surfiace and pulp chamber temperatures developed during electrothermal bonding

The rationale of electrothermal bonding is based on the premise that when an electric current is passed across the beaks of tweezers holding a stainless steel orthodontic bracket, heat will be generated by virtue of the electrical resistance of the steel bracket. This study was carried out to evaluate the temperatures generated on the tooth surface at the bracket/tooth interface and within the pulp chamber during electrothermal bonding. Temperatures were recorded with 5 and 7.5 A current levels applied as a 1 second pulse with time intervals between pulses of 1, 2, 3, and 4 seconds. The data showed that after three pulses with a 5 A current, the temperature on the tooth surface ranged between 43.3° C (4 second intervals) to 53.6° C (1 second intervals). By using a 7.5 A current, the temperature ranged from 77.5° C (4 second intervals) to 85.9° C (1 second intervals). The pulp chamber temperatures were evaluated in vitro for a mandibular incisor, the maxillary central and lateral incisors, a canine, a premolar, and a molar. The pulp chamber temperature of a mandibular incisor responded most, whereas that of premolars and molars responded least to temperature changes on the labial surface. The increase in mandibular incisor pulp chamber temperature after three pulses was 2.1° C for 5 A and 2.8° C for 7.5 A current while for a premolar the increase ranged from 0.9° C to 1.6° C. On the basis of current evidence the increase in pulp chamber temperatures during electrothermal bonding may be considered to be clinically safe. (Am J Orthod Dentofac Orthop 1996;109:506-14.)

Heat generated by grinding during removal of ceramic brackets

When ceramic brackets fracture during treatment or at the time of debonding, it may become necessary to remove residual fragments by grinding with a handpiece. However, the grinding of ceramic surfaces may generate temperatures high enough to have detrimental effects on dental pulp. Intrapulpal temperature measurements were made on extracted teeth during bracket grinding with a small thermocouple probe fixed to the pulpal wall subjacent to the bracket position. These measurements were then compared with established threshold temperatures that have been reported to cause pulpal pathosis. We removed 122 ceramic brackets (A-Company Starfire, GAC Allure, and Unitek Transcend) from eight extracted teeth by grinding with high-speed diamond burs or low-speed green stones, both with and without air or water coolant. It was determined that low-speed grinding without coolant resulted in a significant (p less than 0.001) increase in pulp chamber temperature for all three types of brackets. Neither high-speed nor low-speed grinding during bracket removal caused a rise in pulp chamber temperature when combined with air or water coolant.