Assessment of compression and strength of divergent screws mounted on miniplates and dynamic compression plate in fixation of mandibular body fractures: an in vitro study.

Achieving compression in the fracture line gap by open reduction and internal fixation leads to more primary bone healing and therefore hastens the healing process and patient's rehabilitation. We aimed to evaluate the application of compression by a modification in screw insertion in miniplates to improve the efficiency of the previous relevant methods. In this in vitro experimental study 20 sheep hemimandibles were prepared. Following intentional fracturing of the hemimandibular bodies, the specimens were divided into two: the control and study groups (n=10 each). The control group was fixed with straight four-hole dynamic compression plate (DCP) without a bar and with parallel screws. The study group was fixed with a straight four-hole miniplate without a bar. Screws were divergently inserted into the bone with an angle of 45°. The differences in the fracture line gap were measured before and after fixation considering the indicators of compression. The strength of the fixation was also assessed with a universal testing machine. The control group provided more compression than the study group (p=0.4). There was no difference in the strength of fixation between the two groups. It is concluded that the application of the miniplates with divergent screws instead of DCP could encompass the advantages of both perspectives such as intraoral incisions and compressive force and prevent the disadvantages of compression plates such as hard adaptation.

Clinical outcomes of dental implants after use of tenting for bony augmentation: a systematic review.

The reconstruction of severely atrophic ridges is often challenging and complicated. We searched the Medline, Embase, and Cochrane databases for articles up to October 2015 that reported the success of all types of tenting for bony regeneration. We extracted data on the size and site of the defect, the number of patients, vertical and horizontal augmentation, survival of dental implants, and complications. Thirteen studies were included, which yielded data on 423 patients with 1111 dental implants. Follow-up periods were more than five years, severely resorbed mandibles were augmented vertically by up to 10mm, and the survival rate of the implants was over 97%. The mean (SD) gain in horizontal width by screw tenting was 3 (0.63)mm, and over 97.6% of dental implants in cortical tenting investigations survived. A tenting approach may reduce the need for large autogenous bone grafts in the reconstruction of severely atrophic ridges and local bony defects, and improves the survival of implants.

Assessment of compression and strength of divergent screws mounted on miniplates for fixation of mandibular fractures: an in vitro experimental study.

An efficient band of tension is critical for the adequate fixation of mandibular fractures, so fixation devices that compress are helpful. We aimed to evaluate the possibility of creating compression using screws inserted divergently into miniplates placed in the tension zone of mandibular fractures and record the effects on the strength of fixation. For this in vitro experimental study we prepared 20 sheep hemimandibles. After angle fractures had been created, the specimens were divided into standard and study groups (n=10 in each). In the standard group the tension zones were fixed in the standard manner with 4-hole miniplates and 4 parallel screws. Those in the study group were fixed as for the standard group but with 4×45° divergent screws. The differences in the gap in the fracture line before and after fixation were measured as indicators of compression. The strength of fixation was also assessed with a universal testing machine in vitro. The amount of compression was significant only in the study group (p<0.001), and there was no difference in the strength of fixation between the two groups (p=0.7). We conclude that divergent drilling and insertion of screws creates more horizontal force when miniplates are used, and results in reduction in the size of the probable gap in the fracture line. Insertion of divergent screws in miniplates may create compression between fractured segments without jeopardising the strength of fixation.