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    Evaluation of the effect of symphysis trauma on fracture pattern after marginal mandibular resection by finite element analysis
    (Churchill Livingstone, 2025) Cetiner, Yunus; Sancar, Bahadir
    Mandibular fractures following marginal mandibular resection (MMR) remain an unresolved issue. The aim of this study is to determine the regions where stresses are likely to concentrate following trauma to the mandible after Marginal Mandibular Resection (MMR), and to identify the potential locations of postoperative fractures. Additionally, the study aims to establish the minimum bone height that can best resist trauma, with the goal of reducing fracture incidence. Using finite element analysis (FEA), 13 mandibular models were created. MMR was performed with constant mesiodistal diameters but increasing vertical resection heights by 5 mm increments. Seven resections were made in the symphysis and six in the body. A force of 1000 N was exerted to the symphysis. The von Mises (VM), maximum principal (Pmax), and minimum principal (Pmin) stress values were evaluated. The results showed that a residual bone height of 18 mm or less in the symphysis and 17 mm or less in the body leads to fractures under trauma. Residual bone height is a critical factor in preventing iatrogenic fracture following MMR. If insufficient bone height remains after MMR, prophylactic internal fixation should be considered to prevent fractures.
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    Evaluation of the pattern of fracture formation from trauma to the human mandible with finite element analysis. Part 1: Symphysis region
    (Wiley, 2023) Sancar, Bahadir; Cetiner, Yunus; Dayi, Ertunc
    Background/AimThe mandible is the largest, strongest bone in the maxillofacial region. When a fracture occurs in the mandible, its location depends on several factors: the direction of the trauma, the angle of the trauma, masticatory muscles and the quality of the bone. The aim of this study was to evaluate the stresses caused by trauma to the symphysis region from different angles. Materials and MethodsComputer-based mandible models were created, and a 2000 N force was applied to the symphysis at three different angles using finite element analysis. Six trauma situations were simulated with the mouth open or closed. Forces were applied to the symphysis at 90 degrees (Model 1) in the anteroposterior direction, 45 degrees (Model 2) in the anteroposterior-inferosuperior direction and 90 degrees (Model 3) in the inferosuperior direction, when the mouth was open or closed. The resulting stress intensity was assessed using finite element analysis. ResultsAs a result of trauma applied to the symphysis region, maximum stresses were found where the impact originated and at the condyle region (Model 2, open mouth: condyle 1 [1172 MPa]). The open mouth position caused higher stress values than the closed mouth position (Model 2, open mouth: condyle 1 [1172 MPa]; closed mouth: symphysis 4 [82 MPa]). The Model 2, open-mouth state (Model 2, open mouth: condyle 1 [1172 MPa]) sustained higher stresses than all the other models. ConclusionThe stress values in the mandible were affected by the force applied to the symphysis region, the angle of impact arrival and the open or closed state of the mouth. Keeping the mouth closed at the time of trauma reduced the stress value. A closed mouth during trauma directed at the symphysis reduced the possibility of mandible fractures.
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    Evaluation of the pattern of fracture formation from trauma to the human mandible with finite element analysis. Part 2: The corpus and the angle regions
    (Wiley, 2023) Sancar, Bahadir; Cetiner, Yunus; Dayi, Ertunc
    Background/AimsAlthough the mandible is the largest and strongest bone of the facial skeleton, it is frequently broken. The fracture location in the mandible depends on the biomechanical features, direction and angle of the trauma, and masticatory muscles. This study aimed to evaluate the stresses caused by trauma to the corpus and angle regions from different angles. Materials and MethodsAfter computer-based mandible models were created using finite element analysis, a force of 2000 Newton(N) was simulated with the mouth open or closed to the corpus and the angle. To the corpus: at 90 degrees (Model 1) in the lateromedial direction, 45 degrees (Model 2) in the lateromedial-inferosuperior direction, and 90 degrees (Model 3) in the inferosuperior direction. To angle: 90 degrees (Model 4) in the lateromedial direction and 45 degrees (Model 5) in the lateromedial-inferosuperior direction. The resulting stress intensity was assessed using FEA. ResultsFollowing the simulated forces, the maximum stress in the mandible occurred in the condylar region, except in Model 3 (Left(L)Corpus2[36 megapascals(MPa)]) in the mouth-closed condition. After traumas in Model 1 (open-mouth: LCondyle2[547 MPa]) and Model 4 (closed-mouth: LCondyle2[607 MPa]), higher stress values occurred in the condyle. In the mouth open-closed state, there was no significant stress change in the condyle region in Model 1 (open-mouth: LCondyle2[547 MPa], closed-mouth:LCondyle2[546 MPa]) or in Model 2 (open mouth: Right(R)Condyle2[431 MPa], closed-mouth:LCondyle2[439 MPa]). In Model 3, lower stress values occurred in the closed-mouth rather than the open-mouth (LCondyle1[167 MPa]) state. In Models 4 and 5, the stress values increased in the mouth-closed condition compared with the mouth-open condition. ConclusionsStress in the mandible is affected by the location of the trauma and the angle of incidence of the blow. In trauma to both the corpus and the angle, the most common area to be fractured is the condyle.
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    Investigation of the effect of impacted third molar position and orientation on bad split fractures in sagittal split ramus osteotomy using finite element analysis
    (Bmc, 2025) Ustundag, Irfan; Mecu, Erkan; Cetiner, Yunus; Simsek, Mehmet Sait
    Background This study aims to evaluate the impact of different angular orientations and buccolingual positions of impacted third molars on the incidence of bad splits during sagittal split ramus osteotomy using finite element analysis. Materials and methods A total of 12 mandibular models were constructed, each representing a unique combination of third molar orientations (vertical, distoangular, horizontal, mesioangular) and positions (buccal, lingual, central). A force of 20 N was applied from the osteotomy line toward the proximal and distal segments to simulate the working principle of the Smith Spreader instrument. Results The maximum principal stress followed the order: vertical > distoangular > horizontal > mesioangular. In terms of positional stress distribution, the buccal position generated the highest stress, followed by lingual and central positions. Similar trends were observed across all stress criteria evaluated. Conclusion The orientation and position of impacted third molars have a direct effect on the risk of bad splits during SSRO. Mesioangular and centrally positioned teeth were associated with lower stress levels, indicating lower risk, while vertically oriented and buccally or lingually positioned molars showed significantly higher stress concentrations. Thus, extraction of high-risk impacted third molars prior to surgery is recommended to reduce the likelihood of complications.
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    Prelacrimal recess morphology in unilateral cleft lip and palate: A cone-beam computed tomography study with surgical implications
    (Churchill Livingstone, 2025) Cetiner, Yunus; Ozen, Duygu Celik; Duman, Suayip Burak
    Cleft lip and palate(CLP) is a deformity that affects the anatomical structure of the nose and the maxillary sinus (MS). In the management of MS pathologies, the prelacrimal recess approach(PLRA), a minimally invasive technique within endoscopic sinus surgery, holds significant importance. This study aims to evaluate the morphometric characteristics of the nasolacrimal duct(NLD) and the prelacrimal recess(PLR), as well as the feasibility of the prelacrimal recess approach(PLRA), in patients with unilateral cleft lip and palate(UCLP) using cone-beam computed tomography(CBCT). CBCT images of both the cleft and non-cleft sides of 60 patients with UCLP were retrospectively analyzed. Morphometric measurements related to the anatomy of the NLD and the PLR were performed and statistically compared.In these patients, the mediolateral diameter of the NLD was found to be significantly narrower on the cleft side(5.10 f 1.29 mm) compared to the non-cleft side(5.74 f 1.28 mm)(p = 0.03). The mediolateral thickness of the PLR was also significantly thinner on the cleft side(1.89 f 1.46 mm) than on the non-cleft side(2.91 f 1.95 mm)(p = 0.01). However, no significant difference was observed in the anteroposterior length of the PLR between the cleft side(5.08 f 2.54 mm) and the non-cleft side (4.64 f 2.67 mm)(p = 0.35).The prelacrimal recess and nasolacrimal canal on the cleft side may be affected in patients with UCLP. CBCT serves as a valuable tool in identifying these anatomical variations, which are frequently associated with congenital deformities such as UCLP and should be carefully considered during surgical planning.
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    Reconstruction of Oronasal Fistulas with Multiple Techniques: A Case Series Including an Orthodontic Appliance-Induced Defect
    (Springer India, 2026) Ciftci, Sezai; Cetiner, Yunus; Ozden, Samet
    Purpose To assess the effectiveness of various surgical techniques for repairing oronasal fistulas (ONFs) and to present clinical cases utilizing multilayer closure and tongue flap combinations. Materials Four ONF patients underwent different repairs: three-layer closure for an orthodontic appliance-induced fistula, double palatal flap with buccal fat pad for a congenital fistula, anteriorly based tongue flap for a recurrent fistula, and autogenous bone grafting with flap reconstruction for dual fistulas. Results Complete closure was achieved in three patients (75%), with one small asymptomatic residual fistula. No major complications were observed during 6-12 months of follow-up. The appliance-induced fistula appears to be the first reported case linked directly to orthodontic devices. Conclusion ONF repair remains complex, with outcomes influenced by defect size and tissue quality. Local flaps are adequate for small defects, whereas larger or recurrent cases benefit from advanced reconstructive methods. Long-term orthodontic appliance use may increase fistula risk, highlighting the need for close monitoring.
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    The effect of specialization on morbidity in lower third molar extraction
    (Elsevier, 2025) Sancar, Bahadir; Musulluoglu, Ferhat; Cetiner, Yunus
    Objectives: Extracting impacted third molar teeth is one of the most common procedures in maxillofacial surgery. After these operations, symptoms such as trismus, pain, and swelling are seen, negatively affecting patient comfort and defined as postoperative morbidities. The surgeon's experience is one of the considerable factors affecting postoperative morbidity. Methods: With our research, we extracted the mandibular impacted molar teeth of 100 patients by oral, teeth, and maxillofacial surgeons and oral and maxillofacial surgery assistants(research assistant). We recorded all patients' pain, swelling, and maximum incisal opening measurements three times: preoperative, postoperative second day, and seventh postoperative day. We determined the operation times by recording the time between the first incision and the last suture. Results: When we compared oral and maxillofacial surgeons and oral and maxillofacial surgery assistants (research assistant), the operating time of the surgeon was shorter (p < 0.001). When we evaluated the facial swelling on the postoperative second and seventh days, we found that the patients operated on by the surgeon had less swelling (p < 0.001, p:0.005). In our postoperative second-day measurement, the oral openness of the patients operated by the surgeon was greater (p:0.035). Conclusion: Performing the impacted third molar operations by an oral and maxillofacial surgeon reduces postoperative morbidity.