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Objective This study aimed to evaluate the effect of various preheating methods applied to bulk-fill composite resins on temperature changes within the pulp chamber. Materials and Methods Ten sound human molars were used. Each tooth was sectioned 2 mm apical to the cementoenamel junction, and the occlusal surface was flattened to leave a 2 mm dentin thickness. Four bulk-fill composite resins were applied at five temperatures (24 °C, 37 °C, 54 °C, 65 °C, and 68 °C) and polymerized using an LED curing unit. Intrapulpal temperature changes were measured with a K-type thermocouple connected to a data logger in a setup simulating pulpal microcirculation. In total, twenty measurements were taken per tooth under each condition. Data were analyzed using one-way ANOVA and post-hoc LSD tests ( p  < 0.05). Results The highest intrapulpal temperature increase was observed at 65 °C in all groups using the VisCalor dispenser. The critical temperature threshold was not exceeded in any sample. Significant differences were found between certain temperatures within individual resin groups ( p  < 0.05), particularly at 65 °C compared to lower temperatures. However, no statistically significant differences were found between different resin types at the same temperatures ( p  > 0.05). Conclusion Preheating of bulk-fill composite resins led to an increase in intrapulpal temperature; however, this rise remained below the threshold that could cause irreversible pulpal damage. Clinical relevance Preheating bulk-fill composites enhances handling and adaptation but may increase intrapulpal temperature. In this study, the temperature rise remained below the critical threshold, suggesting that the procedure is clinically safe.

ObjectivesTo evaluate the effectiveness of the 980-nm diode laser for dentinal tubule occlusion, measure the intrapulpal temperature, and investigate the dental pulp response.Materials and methodsThe dentinal samples were randomly divided into G1–G7 groups: control; 980-nm laser irradiation (0.5 W, 10 s; 0.5 W, 10 s × 2; 0.8 W, 10 s; 0.8 W, 10 s × 2; 1.0 W, 10 s; 1.0 W, 10 s × 2). The dentin discs were applied for laser irradiation and analyzed by scanning electron microscopy (SEM). The intrapulpal temperature was measured on the 1.0-mm and 2.0-mm thickness samples, and then divided into G2–G7 groups according to laser irradiation. Moreover, forty Sprague Dawley rats were randomly divided into the laser-irradiated group (euthanized at 1, 7, and 14 days after irradiation) and the control group (non-irradiated). qRT-PCR, histomorphology, and immunohistochemistry analysis were employed to evaluate the response of dental pulp.ResultsSEM indicated the occluding ratio of dentinal tubules in the G5 (0.8 W, 10 s × 2) and G7 (1.0 W, 10 s × 2) were significantly higher than the other groups (p < 0.05). The maximum intrapulpal temperature rises in the G5 were lower than the standard line (5.5 ℃). qRT-PCR showed that the mRNA expression level of TNF-α and HSP-70 upregulated significantly at 1 day (p < 0.05). Histomorphology and immunohistochemistry analysis showed that, compared with the control group, the inflammatory reaction was slightly higher at the 1 and 7 days (p < 0.05) and decreased to the normal levels at 14 days (p > 0.05).ConclusionsA 980-nm laser at a power of 0.8 W with 10 s × 2 defines the best treatment for dentin hypersensitivity in terms of compromise between the efficacy of the treatment and the safety of the pulp.Clinical relevanceThe 980-nm laser is an effective option for treating dentin sensitivity. However, we need to ensure the safety of the pulp during laser irradiation.

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.

Objectives This study sought to assess intrapulpal temperature rise following two dentin hypersensitivity (DH) treatment protocols using the 810-nm diode laser. Materials and methods In this randomized clinical trial, 45 maxillary and mandibular incisors and premolars were randomly divided into three groups primary phase (no intervention), 1 W diode laser for 10 s (group 1), and 0.5 W diode laser for 60 s (group 2). In all groups, the access cavity was prepared, and the thermocouple was placed in the pulp chamber and fixed by Cavit. Intrapulpal temperature was measured immediately after access cavity preparation and every minute for 10 min in the primary phase. In the second phase group 1, the temperature was measured with 2-s intervals after irradiation for 10 s and group 2, with 15-s intervals after irradiation for 60 s. Data were analyzed using repeated measures ANOVA and t test ( P  ≤ 0.05). Results The mean stabilized baseline temperature was 32 °C. The mean temperature rise was < 5 °C, with no significant difference between groups 1 and 2 ( P  = 0.6). However, 17% and 11% of teeth in groups 1 and 2, respectively, showed a temperature rise > 5 °C. In both experimental groups, the stabilized temperature after laser irradiation was significantly higher than the baseline temperature ( P  < 0.05), with no significant difference between the two groups ( P  > 0.05). Time to stabilize temperature after irradiation in group 1 was significantly shorter than that in group 2 ( P  < 0.05). Conclusion Both the tested protocols seem to be safe regarding intrapulpal temperature rise. However, considering the slight overheating observed in a small percentage of teeth in both groups, caution must be taken in the use of these protocols for the treatment of DH.

In the present work, the influence of external cooling on the temperature rise in the tooth pulpal chamber during femtosecond laser ablation was investigated. The influence of the cooling method on the morphology and constitution of the laser-treated surfaces was studied as well. The ablation experiments were performed on dentin specimens using an Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs, 1030 nm). Cavities were created by scanning the specimens at a velocity of 5 mm/s while pulsing the stationary laser beam at 1 kHz and with fluences in the range of 2–14 J/cm 2 . The experiments were performed in air and with surface cooling by a lateral air jet and by a combination of an air jet and water irrigation. The temperature in the pulpal chamber of the tooth was measured during the laser experiments. The ablation surfaces were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The temperature rise reached 17.5 °C for the treatments performed with 14 J/cm 2 and without cooling, which was reduced to 10.8 ± 1.0 and 6.6 ± 2.3 °C with forced air cooling and water cooling, respectively, without significant reduction of the ablation rate. The ablation surfaces were covered by ablation debris and resolidified droplets containing mainly amorphous calcium phosphate, but the amount of redeposited debris was much lower for the water-cooled specimens. The redeposited debris could be removed by ultrasonication, revealing that the structure and constitution of the tissue remained essentially unaltered. The present results show that water cooling is mandatory for the femtosecond laser treatment of dentin, in particular, when high fluences and high pulse repetition rates are used to achieve high material removal rates.

This study was done to determine the amount of lasing time required to remove ceramic brackets safely without causing intrapulpal damage by using Er:YAG laser with the scanning method. Part 1: 80 bovine mandibular incisors with ceramic brackets were randomly assigned into four groups of 20 as one control and three study groups. In the study groups, brackets were debonded after lasing for 3, 6, and 9 s, whereas debonding was performed without lasing in the control group. Shear bond strengths and ARI scores were also measured. Part 2: 30 human premolars with ceramic brackets were randomly divided into three groups of ten, as 3, 6, and 9 s of lasing durations. Intrapulpal temperature was measured at the same lasing times by a thermocouple. Statistically significant lower shear bond strengths were found in study groups compared to the control. A negative correlation was seen between the bond strengths and ARI scores in such a way that, as the shear bond strengths decreased, the ARI scores increased. Temperature increases for all the study groups were measured below the 5.5°C benchmark. All lasing times were effective for debonding without causing enamel tear outs or bracket failures. The temperature proportionally increased with the extension of the lasing duration. Six-second lasing by the scanning method using Er:YAG laser was found to be the most effective and safest way of removing the ceramic brackets without causing damage to the enamel and pulpal tissues.

Objectives: It was aimed to investigate the temperature changes in primary teeth pulp chamber during the curing/setting of bulk-fill restorative materials with different nanoparticle contents. Methods: Twenty-five extracted, primary mandibular second molars were prepared as a Class II cavity. Five bulk-fill restorative materials consisting of Equia Fil (HVGIC), glass carbomer (GC) cement, Sonic Fill (SF), X-tra Fil (XF), and Quix Fil (QF) were tested. The measurement of the pulp chamber temperature changes (starting temperature 37°C) during setting/curing was performed with a J type thermocouple. The data, differences between highest and initial temperature values, were recorded and analyzed by one-way ANOVA. Results: The temperature changes in the pulp chamber were in EF (2.81°C), GC (7.92°C), SF (3.33°C), XF (3.43°C), and QF (3.02°C). There were statistically significant differences between temperature changes in groups (P < 0.05). Conclusion: The tested bulk-fill resin composites and high-viscosity glass ionomer cement do not increase the intrapulpal temperature in primary teeth during the curing/setting.

It is suggested that pulpal fluid circulation has an impact on pulp temperature increase during heat-generating dental treatment procedures. Thus, the aim of the study was to assess the effect of a simulated pulpal fluid circulation on temperature changes inside the pulp chamber following laser irradiation of the tooth surface. Twenty freshly extracted human multirooted teeth were included and cross-sectioned along the long axis exposing two root canals each. The pulp chamber and root canals were cleaned from remaining soft tissues to achieve access for a temperature sensor and two cannulas to allow fluid circulation. Cross sections were glued together, and the roots were encased with silicone impression material to ensure the position of the connected devices. Each tooth was irradiated by employing a neodymium-doped yttrium orthovanadate (Nd:YVO 4 ) laser at 1,064 nm with a pulse duration of 9 ps and a repetition rate of 500 kHz. A commercially available scanning system (SCANcube 7, SCANLAB) deflected the beam by providing rectangular irradiated areas of 0.5 mm edge length. Measurements were performed with four different settings for fluid circulation: without any water and with water (23 °C) at a flow rate of 6, 3, and 0 ml/min. The primary outcome measure was the maximum temperature difference (Δ T ) after laser irradiation. Highest temperature changes (median 3.6 K, range 0.5–7.1 K) could be observed without any fluid inside the pulp chamber. Water without circulation decreased Δ T values statistically significantly (median 1.4 K, range 0.2–4.9 K) ( p  < 0.05). Lowest temperature changes could be observed with a water flow rate of 6 ml/min (median 0.8 K, range 0.2–3.7 K) ( p  < 0.05). Pulpal fluid circulation has a cooling effect on temperature increase caused by laser irradiation of dental hard tissues. Studies on heat generation during dental treatment procedures should include this aspect to assess a potential thermal injury of pulp tissue.

Statement of Problem: The provisional restorative materials in fixed prosthodontics are basically bis-GMA resins which releases exothermic temperature while polymerization which can damage the pulp. Intrapulpal temperature exceeding 42.5°C found to result in irreversible damage to the pulp. The remaining thickness of dentine after tooth preparation control the conduction of heat released by the resins. Purpose:(1) To quantify the temperature changes in the pulp chamber using different provisional restorative materials. (2) To evaluate the peak temperature time of different materials used. (3) To compare the intrapulpal temperature changes with a variation in the width of the finish line. Methodology: Two intact mandibular molars were selected and designated as Specimen A and B. Tooth preparation was done to prepare a finish line of 1.2 mm and 1 mm width, respectively. Three provisional restorative materials were considered and they were grouped as Group I-Cool temp, Group II-Protemp-4, Group III-Integrity. A J thermocouple probe was placed into the pulp chamber to determine the rise in temperature. The temperature was recorded during polymerization at 30-s intervals until the peak temperature was reached. The same procedure was repeated for fabricating remaining provisional crowns. A total of 45 provisional crowns were fabricated for each specimen. Results: Kruskal-Wallis test revealed that there was a significant difference in the temperature changes associated with the provisional restorative materials used. All the three provisional restorative materials were compared for 1.2 mm and 1 mm wide finish line. Integrity produced the highest temperature rise and the maximum temperature recorded was 40.2°C in 1.2 mm wide finish line. However, for a 1 mm wide finish line, Protemp-4 produced the highest temperature rise and the maximum temperature recorded was 40.3°C. It was observed that peak temperatures with Specimen B were more when compared with Specimen A. Conclusion: Cool temp showed least temperature rise in the pulp chamber. The order of rise in intrapulpal temperature in tested provisional materials using direct technique would be Cool temp, Integrity, and Protemp-4.

This in vitro study was designed to measure and compare the amount of temperature rise in the pulp chamber of the teeth exposed to different light curing units (LCU), which are being used for curing composite restorations. The study was performed in two settings; first, an in vitro and second was mimicking an in vivo situation. In the first setup of the study, three groups were formed according to the respective three light curing sources. i.e. quartz-tungsten-halogen (QTH) unit and two light-emitting diode (LED) units (second and third generations). In the in vitro setting, direct thermal emission from three light sources at 3 mm and 6 mm distances, was measured with a k-type thermocouple, and connected to a digital thermometer. For a simulation of an in vivo situation, 30 premolar teeth were used. Class I Occlusal cavity of all the teeth were prepared and they were restored with incremental curing of composite, after bonding agent application. While curing the bonding agent and composite in layers, the intrapulpal temperature rise was simultaneously measured with a k-type thermocouple. The first setting of the study showed that the heat produced by irradiation with LCU was significantly less at 6 mm distance when compared to 3 mm distance. The second setting of the study showed that the rise of intrapulpal temperature was significantly less with third generation LED light cure units than with second generation LED and QTH light cure units. As the distance from the light source increases, less irradiation heat is produced. Third generation LED lights cause the least temperature change in the pulp chamber of single rooted teeth.