Background
Different designs of surgical drilling systems have been developed for the purpose of static Computer‐Assisted Implant Surgery (sCAIS), but there is at present little understanding of how design principles affect the accuracy of implant placement.
Purpose
The aim of this in vitro study was to compare the accuracy of implant placement among five drilling systems of sCAIS in a controlled experimental setting.
Materials and Methods
Twenty‐five 3D printed models with two edentulous bilateral premolar spaces were allocated to five different drilling systems: group A: sleeve‐in‐sleeve, group B: sleeve‐in‐sleeve with self‐locking, group C: mounted sleeve‐on‐drill, group D: integrated sleeve‐on‐drill with metal sleeve in the guide, group E: integrated sleeve‐on‐drill without metal sleeve. Models were scanned with CBCT and optical scanner. All implants were digitally planned and 10 implants placed with sCAIS in each group. Postoperative 3D deviation of placed vs planned position was measured by means of platform, apex and angular deviation. Data was analyzed using Kruskal‐Wallis test (P ≤ .05). Pairwise comparisons were tested with Dunn's test with adjusted P values.
Results
The overall platform deviation ranged from 0.42 ± 0.12 mm (group B) to 1.18 ± 0.19 mm (group C). The overall apex deviation ranged from 0.76 ± 0.22 mm (group B) to 1.95 ± 0.48 mm (group D). The overall angular deviation ranged from 2.50 ± 0.89 degree (group B) to 5.30 ± 1.04 degree (group E). Group A and B showed significantly less angular deviation than groups D and E (P < .05). There was no statistically significant differences in all parameters between group A and B, as well as between group D and E (P > .05).
Conclusions
Significant differences were found with regards to accuracy among the five sCAIS systems tested, suggesting that the drilling protocol, the devices used and the design principles of the guides could influence the accuracy of implant placement.
Suitable diet for cancer survivors remains an unresolved challenge. Increased glucose utilization is a hallmark of various cancers. Therefore, alternative carbohydrate supplying normal tissue but retarding cancer growth is needed. This study investigated the effect of sugar alcohols on the proliferation of oral cancer cells compared to nontransformed cells and explored the mechanism. Six oral squamous cell carcinoma (CAL-27, FaDu, SCC4, SCC9, SCC15, and SCC25) and one nontransformed oral keratinocyte (OKF6/TERT2) lines were cultured in media containing 1 mg/ml glucose and 5.8 mg/ml xylitol or sorbitol, yielding equal energy input to control group (4.5 mg/ml glucose). Partial substitution of glucose with sugar alcohols especially xylitol significantly suppressed proliferation of oral cancer but not nontransformed cells. Despite the addition of isocaloric quantities of the sugars, cancer cells exposed to low glucose plus xylitol had retarded ATP generation and decreased activity of phosphofructokinase (PFK), the rate-limiting enzyme in glycolysis. Furthermore, D-xylulose, its key metabolic intermediate, enhanced the anticancer effect of xylitol. These findings suggested a selective anticancer activity of xylitol and the potential mechanism involving inhibition of glucose utilization. Partial substitution of glucose with xylitol may be a proper nutrient for oral cancer survivors, deserving further investigation in animal and clinical settings.
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