Influence of Material, Sterilization, and Disinfection on the Accuracy of Three-Dimensional Printed Surgical Templates: An In Vitro Study.

OBJECTIVES: To evaluate the influence of the three-dimensional (3D) printing technology, material, sterilization, and disinfection on the accuracy of guided surgical templates. MATERIAL AND METHODS: Fifty printed resin surgical templates were designed and fabricated using a digital light processing 3D printer with a photopolymerizing resin, and 50 printed metal surgical templates were designed and fabricated using a selective laser melting 3D printer with a titanium alloy. Templates from both groups were randomly divided into five subgroups involving different sterilization and disinfection procedures. The group without any sterilization or disinfection procedure served as the control group, whereas the other groups were used as the study groups (hydrogen peroxide gas plasma sterilization, 5% povidone-iodine disinfection, 75% ethyl alcohol disinfection, and steam autoclave sterilization). Implant simulations were performed on the 3D-printed resin models, and postoperative impressions were acquired with scan bodies attached to the implants. All surgical templates were digitally scanned. The root mean square was used to determine and quantify fabrication accuracy and reproducibility, and the definitive and planned implant positions were compared. RESULTS: The printed resin templates exhibited lower fabrication accuracy and reproducibility, as well as higher 3D deviations, after steam autoclave sterilization (p < 0.001); however, the printed metal templates were not affected by the different sterilization or disinfection procedures (p > 0.05). CONCLUSIONS: Printed metal surgical templates are viable alternatives for guided implant surgery. Preoperative steam or gas plasma sterilization is recommended, especially for metal templates, as resin templates show deformation and decreased accuracy after steam sterilization. TRIAL REGISTRATION: chictr.org.cn number: ChiCTR2400081334.

The three-dimensional stability and accuracy of 3D printing surgical templates: An In Vitro study.

OBJECTIVE: To evaluate the three-dimensional (3D) stability and accuracy of additively manufactured surgical templates fabricated using two different 3D printers and materials. MATERIALS AND METHODS: Forty surgical templates were designed and printed using two different 3D printers: the resin group (n = 20) used a digital light processing (DLP) 3D printer with photopolymer resin, and the metal group (n = 20) employed a selective laser melting (SLM) 3D printer with titanium alloy. All surgical templates were scanned immediately after production and re-digitalized after one month of storage. Similarly, the implant simulations were performed twice. Three-dimensional congruency between the original design and the manufactured surgical templates was quantified using the root mean square (RMS), and the definitive and planned implant positions were determined and compared. RESULTS: At the postproduction stage, the metal templates exhibited higher accuracy than the resin templates (p < 0.001), and these differences persisted after one month of storage (p < 0.001). The resin templates demonstrated a significant decrease in three-dimensional stability after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05). No significant differences in implant accuracy were found between the two groups. However, the resin templates showed a significant increase in apical and angular deviations after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05). CONCLUSION: Printed metal templates showed higher fabrication accuracy than printed resin templates. The three-dimensional stability and implant accuracy of printed metal templates remained unaffected by one month of storage. CLINICAL SIGNIFICANCE: With superior three-dimensional stability and acceptable implant accuracy, printed metal templates can be considered a viable alternative technique for guided surgery.

Guided bone regeneration for peri-implant augmentation: A retrospective study comparing two surgical techniques with a mean follow-up of 26 months.

OBJECTIVES: To introduce a modified guided bone regeneration (GBR) technique using intact periosteum and deproteinized bovine bone mineral (DBBM) for peri-implant augmentation and compare the clinical outcomes with those of conventional GBR. MATERIALS AND METHODS: Patients who received peri-implant augmentation in posterior sites between 2015 and 2021 were reviewed in this study. Group A was treated with a modified GBR technique, and Group B was treated with conventional GBR. For group comparison, propensity score matching was performed with a sensitivity analysis. The implant survival rate, dimensional changes in hard tissue, marginal bone loss (MBL), and peri-implant parameters were evaluated. RESULTS: In total, 114 implants from 98 patients were included. The implant survival rates were 95.74% in Group A and 95.00% in Group B during the follow-up period. At 6 months, the median horizontal thickness was recorded at 0.87 mm (IQ1-IQ3 = 0.00-1.75 mm) in Group A, exhibiting a relatively lower value compared to the corresponding measurement of 0.98 mm (IQ1-IQ3 = 0.00-1.89 mm) in Group B (p = .937). Vertical height displayed no statistically significant intergroup difference between the two groups (p = .758). The mean follow-up period was 25.83 ± 12.93 months after loading in Group A and 27.47 ± 21.29 months in Group B (p = .761). MBL and peri-implant parameters were comparable between the two groups. CONCLUSIONS: Within the limitations of this study, the modified GBR technique using intact periosteum and DBBM grafting might be a viable alternative to correct bone defects around implants in molar and premolar sites.

Prevalence of cerebral palsy in children aged 1 - 6 in Guangxi, China.

OBJECTIVE: To study the prevalence of cerebral palsy (here in after referred to CP) in children aged 1 - 6 in Guangxi, China, and its epidemiologic characteristics and relevant risk factors. METHODS: Investigations on the prevalence and etiology of CP in children at ages of 1 - 6 were conducted in Nanning, Hengxian and Qinzhou of Guangxi from June to December in 1998, with a cluster sampling. RESULTS: Totally, 150 806 children aged 1 - 6 were investigated in Nanning, Hengxian and Qinzhou of Guangxi, with 89 418 boys and 61 388 girls. Among them, 193 children were diagnosed as CP, with a prevalence rate of 1.28 per thousand, higher in boys (136 cases, 1.52 per thousand ) than in girls (57 cases, 0.93 per thousand ), with statistical significance (chi(2) = 9.536 7, P = 0.02). Logistic regression analysis showed that risk factors for CP were children who could not cry after birth (neonatal asphyxia), Apgar score less than eight, delivery at lower level of maternity hospital, number of mother's gravidity, no prenatal checks for mothers, and taking antipyretics and preserved food with salt during pregnancy. CONCLUSIONS: Prevalence of CP in children of Guangxi was at a lower level in comparison with that in other areas at home and abroad, which, maybe, was related with the lower neonatal survival and higher infant mortality.