Assessment of jaw bone mineral density, resorption rates, and oral health in patients with severe hemophilia: a case-control study.

OBJECTIVE: Knowledge about oral hygiene, gingival bleeding, mineral density, and resorption of jaw bones in patients with hemophilia is limited. We evaluated the periodontal and bone status in such patients.  Material and methods: Forty-eight patients with severe type A/B hemophilia and 49 age- and sex-matched controls were included. Assessments included simplified oral hygiene index (OHI-S), calculus index, debris index, gingival index (GI), gingival bleeding time index (GBTI), and decayed, missing, and filled teeth index (DMFTI). Bone resorption was evaluated using panoramic mandibular index (PMI), mental index (MI), and alveolar crest ratio (ACR). Mineral density in the condyle, angulus, and premolar areas was assessed using fractal analysis, with fractal dimensions denoted as condyle fractal dimension (CFD) for the condyle, angulus fractal dimension (AFD) for angulus, and premolar fractal dimension (PFD) for premolar region. RESULTS: The mean scores were DMFTI = 11.77, OHI-S = 2.44, PMI = 0.268, MI = 5.822, GI = 3.02, GBTI = 2.64, ACR = 2.06, CFD = 1.31, AFD = 1.31, and PFD = 1.17 in the hemophilia group and DMFTI = 11.449, PMI = 0.494, MI = 7.43, GI = 0.67, GBTI = 0.98, OHI-S = 1.45, ACR = 2.87, CFD = 1.35, AFD = 1.35, and PDF = 1.23 in the control group. Differences were significant for all parameters (p < 0.005) except for the DMFTI index.  Conclusions: Because of poor oral hygiene, high bone resorption, and low bone mineral density in these patients, clinicians should consider potential bone changes when planning to treat these patients.

Comparison of implant placement at crestal and subcrestal levels in aesthetic zone: A finite element analysis.

PURPOSE: The success rate of the implant treatment, including aesthetics and long-term survival, relies heavily on preserving crestal peri-implant bone, as it determines the stability and long-term outcomes. This study aimed to demonstrate the stress differences in the crestal bone resulting from dental implant placement at various depths relative to the crestal bone level using finite element analysis. MATERIALS AND METHODS: Three study models were prepared for implant placement at the crestal bone level (CL), 1 mm depth (SL-1), and 2 mm depth (SL-2). Implants were placed in the maxillary central incisor region of each model, and 100 N vertical and oblique forces were applied. The von Mises, maximum principal (tensile), and minimum principal (compressive) stresses were evaluated. RESULTS: The CL model exhibited the highest stresses on the implant, abutment, and abutment screws under vertical and oblique forces. For maximum principal stress in the crestal bone under vertical force, the SL-2, SL-1, and CL models recorded values of 6.56, 6.26, and 5.77 MPa, respectively. Under oblique forces, stress values for SL-1, SL-2, and CL were 25.3, 24.91, and 23.76 MPa, respectively. The CL model consistently exhibited the lowest crestal bone stress at all loads and the highest stress values on the implant and its components. Moreover, considering the yield strengths of the materials, no mechanical or physiological complications were noted. CONCLUSIONS: Placing the implant at the crestal level or subcrestally beyond the cortical layer could potentially reduce stress and minimize crestal bone loss. However, further studies are warranted for confirmation.

Impact of bone levels on stress distribution around all-on-four concept: A 3-D finite element analysis.

This study aimed to investigate the impact of implant placement levels within the bone on stress distribution in the context of the All-on-Four concept. In this Finite Element Analysis(FEA), two 4.1 mm x 10 mm implants were axially placed in the anterior region of the jawbone, while two 4.1 mm x 14 mm implants were tilted at 30 ° in the posterior region following the all-on-four concept. In the EC scenario, all implants were inserted at the equicrestal level. In other scenarios, implants were positioned at 1 mm and 2 mm subcrestal levels (SC1, SC2). In all groups, the prosthesis was designed to replicate a group-function occlusion. A total load of 450 N was applied to the prosthesis. Upon deeper implant placement below the crest level, a trend of decreasing Von Mises stresses was observed in both implants and implant fragments. The highest Pmax value in the bone was recorded in SC-2, characterized by the absence of cortical bone support, with values of 3.16 N/mm2 in the anterior region and 1.55 N/mm2 in the posterior region. Conversely, the lowest Pmax values were noted in SC-1 for the anterior implant (2.67 N/mm2) and the EC for the posterior implant (0.87 N/mm2). Implant placements devoid of cortical bone support result in stress transmission from the implant and its components to the peri-implant bone. Optimal stress minimization is achieved by placing anterior axial angle implants deeper than the crest level while retaining cortical bone support and positioning posterior tilted implants at the crest level.