The Biomechanical Investigation of Osseointegration Levels in Titanium Implants Simultaniously Placed with Different Bone Grafts.

BACKGROUND: Dental implant-supported prostheses have been scientifically accepted and have been a common treatment choice in the case reconstructing of partial or total tooth loss. In additon, bone grafts (alloplast, xsenograft, allograft) are frequently used in implant and sinus lift surgical procedures. AIM: The aim of this study is to investigate the bone-implant osseointegration levels of titanium implants simultaniously placed with different bone grafts. MATERIALS AND METHODS: In the study, 32 female S. Dawley rats were divided into four groups. In the control group (n = 8), turned surface implants with a 2.5 mm diameter and a 4 mm length were placed in the tibia of the rats without the use of a graft material. In the experimental groups, bone cavities were opened in the tibias of the rats and a synthetic (alloplast) graft (n = 8), human allograft (n = 8), and bovine xsenograft (n = 8) were placed simultaniously with a 2.5 mm diameter and a 4 mm length turned surface titanium implants. The cavities in the experimental groups were opened with a 4 mm diameter and a 5 mm length. After 8 weeks of recovery, all rats were sacrificed at the end of the experimental period. The implants and surrounding bone tissue were removed. The removed tissue was subjected to biomechanical analysis in order to evaluate bone-implant osseointegration and peri-implant new bone formation. The Kolmogorov-Smirnov test, Kruskal-Wallis test, and Mann-Whitney U-test were used in the study. Significance was evaluated at the P < 0.05 level. RESULTS: In the biomechanical analyses, it was determined that there was no statistically significant difference between the control group and the other three groups in which different graft materials were applied in terms of bone-implant osseointegration (P > 0.05). In other words, in the biomechanical analyses, no statistical difference was found between any of the groups. CONCLUSIONS: As a result of this study, it can be thought that different graft materials can be successfully used in peri-implant-guided bone regeneration and may be an alternative to autogenous grafts.

Randomized controlled trial of 8 weeks' vs 12 weeks' interval between neoadjuvant chemoradiotherapy and surgery for locally advanced rectal cancer.

AIM: The aim was to compare the pathological complete response (pCR) rate at 8 compared to 12 weeks' interval between completion of neoadjuvant chemoradiotherapy (CRT) and surgery in patients with locally advanced rectal cancer. METHOD: This was a randomized trial which included a total of 330 patients from two institutions. Patients with locally advanced (T3-4N0M0, TxN+M0) rectal cancer were randomized into 8- and 12-week interval groups. All the patients received long-course CRT (45 Gy in 1.8 Gy fractions and concomitant oral capecitabine or 5-fluorouracil infusion). Surgery was performed at either 8 or 12 weeks after CRT. The primary end-point was pCR. Secondary end-points were sphincter preservation, postoperative morbidity and mortality. RESULTS: Two-hundred and fifty-two patients (n = 125 in the 8-week group, n = 127 in the 12-week group) were included. Demographic and clinical characteristics were similar between groups. The overall pCR rate was 17.9% (n = 45): 12% (n = 15) in the 8-week group and 23.6% (n = 30) in the 12-week group (P = 0.021). Sphincter-preserving surgery was performed in 107 (85.6%) patients which was significantly higher than the 94 (74%) patients in the 12-week group (P = 0.016). Postoperative mortality was seen in three (1.2%) patients overall and was not different between groups (1.6% in 8 weeks vs 0.8% in 12 weeks, P = 0.494). Groups were similar in anastomotic leak (10.8% in 8 weeks vs 4.5% in 12 weeks, P = 0.088) and morbidity (30.4% in 8 weeks and 20.1% in 12 weeks, P = 0.083). CONCLUSION: Extending the interval between CRT and surgery from 8 to 12 weeks resulted in a 2-fold increase in pCR rate without any difference in mortality and morbidity.