A retrospective cohort study on the aetiology and characteristics of maxillofacial fractures presenting to a tertiary centre in the UK

Mandibular biomechanics rehabilitated with different prosthetic restorations under normal and impact loading scenarios

BACKGROUND

Restorative treatment options for edentulous patients range from traditional dentures to fixed restorations. The proper selection of materials greatly influences the longevity and stability of fixed restorations. Most prosthetic parts are frequently fabricated from titanium. Ceramics (e.g. zirconia) and polymers (e.g. PEEK and BIOHPP) have recently been included in these fabrications. The mandibular movement produces complex patterns of stress and strain. Mandibular fractures may result from these stresses and strains exceeding the critical limits because of the impact force from falls or accidents. Therefore, it is necessary to evaluate the biomechanical behavior of the edentulous mandible with different restorations under different loading situations.

OBJECTIVE

This study analyzes the biomechanical behavior of mandibles after four prosthetic restorations for rehabilitation under normal and impact loading scenarios.

MATERIAL AND METHODS

The mandibular model was constructed with a fixed restoration, which was simulated using various materials (e.g. Titanium, Zirconia & BIOHPP), under frontal bite force, maximum intercuspation, and chin impact force. From the extraction of tensile and compressive stresses and strains, as well as the total deformation of mandible segments, the biomechanical behavior and clinical situations were studied.

RESULTS

Under frontal bite, the anterior body exhibited the highest tensile (60.34 MPa) and compressive (108.81 MPa) stresses using restoration 4, while the condyles and angles had the lowest tensile (7.12 MPa) and compressive (12.67 MPa) stresses using restoration 3. Under maximum intercuspation, the highest tensile (40.02 MPa) and compressive (98.87 MPa) stresses were generated on the anterior body of the cortical bone using restoration 4. Additionally, the lowest tensile (7.7 MPa) and compressive (10.08 MPa) stresses were generated on the condyles and angles, respectively, using restoration 3. Under chin impact, the highest tensile (374.57 MPa) and compressive (387.3 MPa) stresses were generated on the anterior body using restoration 4. Additionally, the lowest tensile (0.65 MPa) and compressive (0.57 MPa) stresses were generated on the coronoid processes using restoration 3. For all loading scenarios, the anterior body of the mandible had the highest stress and strain values compared with the other segments. Compared to the traditional titanium restoration.2, restoration.1(zirconia) increases the tensile and compressive stresses and strains on the mandibular segments, in contrast to restoration.3 (BIOHPP). In addition, zirconia implants exhibited higher displacements than the other implants.

CONCLUSION

In the normal loading scenario, the tensile and compressive stresses and strains on the mandible were within the allowable limits when all restorations were used. Under the chin impact loading scenario, the anterior body of the mandible was damaged by restorations 1 and 4.

Predictors of Facial Fractures in Trauma Patients: Retrospective Review at a Level I Trauma Center

BACKGROUND

The incidence and causes of facial fractures differ between patients, but patterns arise within populations. These patterns vary by gender, age, and between countries. This study aims to determine variables to identify patients at risk for facial fractures in a United States trauma population.

METHODS

This is a single-center study of Trauma Registry data, inclusive of years July 1, 2016, to January 31, 2022. Inclusion criteria were based upon all trauma patients. Confirmation of a non-isolated facial fracture (dependent variable) was verified using ICD10 diagnosis codes. A logistic regression was performed in SPSS to ascertain the effects of predictor variables on the likelihood that a trauma patient will experience a facial fracture.

RESULTS

20377 patients were included in the analysis based upon the requirements specified in the methods section; 1575 (7%) had a positive facial fracture. The logistic regression model was statistically significant (N = 18507, P < .01). Significant risk factors for facial fracture identified included helicopter transport (OR = 1.35, P < .01) and increasing injury severity scores (OR = 1.07, P < .01). Modes of injury most likely to predict facial fracture included assault (OR = 6.62, P < .01), moped (OR = 2.02, P < .01), and motorcycle trauma (OR = 1.55, P < .01). The discharge disposition most likely among facial fracture patients included short-term general hospital (OR = 1.71, P < .01) and intermediate care facility (OR = 4.47, P < .01).

CONCLUSIONS

Patients with traumatic injuries from assault, moped, and motorcycle accidents were more likely to present with facial fractures. These patients had more severe injuries, seen as increased ISS scores, higher likelihood of transport by helicopter, and the need for additional care after discharge.

Bond Strength and Adhesion Mechanisms of Novel Bone Adhesives

Bone adhesives offer distinct advantages over the use of screws to attached internal fixation plates (IFPs). As the chemical composition of bone is similar to dentine, it is possible that the types of monomers used to make dentine adhesives could be utilised to affix IFPs to bone. The ability to attach a bio-resorbable IFP to porcine bone was assessed for the monomer 10-methacryloyloxydecyl dihydrogen phosphate (MDP), used either as a homopolymer or a copolymer with urethane dimethacrylate (MDP + U). Additionally, the addition of a priming step (MDP + U + P) was evaluated. The chemical interactions of the monomers with bone were assessed using XRD and imaged using TEM, revealing the formation of nano-layered structures with the MDP primer, something we believe has not been reported on bone. In a 6-week artificial aging study both MDP + U and MDP + U + P demonstrated adequate shear bond strength to affix bio-resorbable IFPs. The cytotoxicity profiles of the adhesive formulations were determined using indirect and direct contact with MC3T3 cells, with indirect conditions suggesting the MDP + U + P is as cytocompatible as the resorbable IFP. The findings of this study suggest our newly developed adhesive has the potential to be used as a bone adhesive to affix bioresorbable IFPs.