Objective:To observe the temperature vaxiation in the pulp chamber during Nd-YAG laser irradiation at tooth cervical portion.Methods:60 extracted permanent teeth were divided into 3 groups (anterior teeth,premolars and molars,n =20).The teeth in each group were further divided into 4 subgroups according to the laser power setting (0.4 W,0.8 W)and interval time(1 0 s,20 s)(n =5).After canal preparation the teeth were fixed and filmed using the parallel projection technique.the thickness of the buccal pulp chamber wall was measured by graphic analyzing software.The buccal cervical portion of the teeth was irradiated through 200 μm optical fiber,Temperature in the pulp was measured by K type thermo-electric couples fixed to the pulp chamber wall.Re-sults:The temperature inside the chamber increased with the higher power setting(P <0.01 ),under the same power setting,longer irradiation duration caused higher temperature rise(P <0.01 ).Greater chamber wall thickness was associated with lower temperature rise.Conclusion:The temperature rise in the pulp chamber during laser irradiation is correlated with laser power setting and the thickness of the irradiated tooth tissue.

Objective: To evaluate the surgical treatment of calcaneal fracture malunion. Methods: A retrospective analysis was conducted of the 19 patients with calcaneal fracture malunion (19 feet) who had been treated from January 2011 to September 2017 at Departments of Joint Surgery and Orthopedic Trauma, The Third Affiliated Hospital, Sun Yat-Sen University. They were 16 males and 3 females with the average age of 36.2 years (from 22 to 57 years). According to Stephens-Sanders classification, the malunion was defined as type Ⅰ in 10 cases, as type Ⅱ in 6 and as type Ⅲ in 3. The patients with malunion of type Ⅰ were treated by lateral wall osteotomy and decompression of long and short peroneus muscles to preserve the subtalar joint, those with malunion of type Ⅱ by lateral wall osteotomy and decompression of long and short peroneus muscles followed by subtalar joint fusion, and those with malunion of type Ⅲ by lateral wall osteotomy, decompression of long and short peroneus muscles, medial oblique osteotomy for correction of varus deformity and subtalar joint fusion via both the medial and lateral approaches. The Maryland functional scores were used to assess the postoperative surgical efficacy. Results: No such complications happened as incision or implant infection, screw breakage or joint non-fusion. Of the 19 patients, 17 were followed up for 18 to 26 months (mean, 20.5 months). The Maryland scores at the final follow-ups were 90.2±7.3, significantly higher than the preoperative values (38.6±5.5) (t=53.370, P<0.001). Conclusions In the surgical treatment of calcaneal fracture malunion, satisfactory clinical efficacy can be achieved by lateral wall osteotomy and preservation of the subtalar joint for patients with maunion of Stephens-Sanders type Ⅰ, and by subtalar fusion for those with maunion of Stephens-Sanders types Ⅱ-Ⅲ.