Biomechanical evaluation of six zygomatic implants versus four zygomatic implants combined with dental implants in the treatment of different maxillary defects.

BACKGROUND: This study aims to compare the biomechanics of six zygomatic implants (ZIs) and dental implants (DIs) combined with four ZIs with different maxilla defects. METHODS: Three-dimensional constructs of the ZIs, DIs human skulls, and maxillary prostheses were created using SolidWorks Software (Version 2015, Dassault Systems SolidWorks Corporation, Waltham, MA, USA). Eight finite element models of the skull with four different alveolar defect types (0-4) were constructed. Type 0: No defect; Type 1: Bilateral posterior defects; Type 2: Right posterior defect; Type 3: Anterior and left posterior defects; Type 4: Bilateral posterior and anterior defects. In two models with the same defect type (for defect types 0-2), six ZIs or two DIs combined with four ZIs were inserted into the maxilla. Six ZIs were inserted in the maxilla models with defect types 3 and 4. Vertical (150 N) and masseteric (300 N) loads were simulated on the prosthesis. The maximum Von Mises stress in the implants/surrounding bone and bone deformation were evaluated. RESULTS: The maximum Von Mises stresses in bone/implant were found highest in the defect type 2 model with four ZIs combined with two DIs. The lowest maximum Von Mises stress for bone was detected in the model with defect type 0 and with six ZIs. CONCLUSION: Among the four types of defects, the posterior unilateral defect caused the highest stress value.

Biomechanical effects of different miniplate use on bone and miniplate systems in multiple mandible fracture: A finite element study.

PURPOSE: The aim of this study is to evaluate the biomechanical efficiency of different miniplates in the treatment of multiple mandibula fractures. MATERIAL AND METHOD: Mandible, miniplates, and screws were modeled using the Solid Works v2015 (Dassault Systèmes, France) program, Subsequently two fracture lines were created on the right parasymphysis and angulus mandible. Models were divided into two main groups according to the plates used in the anterior fracture line: group A, 2 piece 4-hole-bar-I plate, and group B, ellipse plate. Each group was divided into five subgroups according to the plates used in the posterior fracture line (I, X, G, 3D, E) and 10 study models were created in total. Under three different biting forces (anterior, right, left), maximum von-Mises stresses seen on miniplates/screws, and Pmax/Pmin stresses seen in the cortically/cancellous bone were analyzed using the Ansys 16.2 software (ANSYS, Inc., USA). Data was visualized using a color distribution scale and interpreted. RESULTS: The highest von-Mises stress, seen in plates, was found in the I plate (353.82 MPa) at the angulus region of model A1. The highest Pmax and Pmin stresses, revealed in cortical bone, were found respectively in model A1 (181.63 MPa) and model B2 (115.01 MPa). The ideal results on plates were seen in models B3 and B5, in which E plates were used in the parasymphysis and G/E plates were used in the angulus region. CONCLUSION: Grid and ellipse plates provide successful results and plate geometry is more critical than number in terms of stress distribution.

The effects of mineral trioxide aggregate and second-generation autologous growth factor on pulpotomy via TNF-α and NF-kß/p65 pathways.

This study aims to investigate the effect of Mineral Trioxide Aggregate (MTA), a bioactive endodontic cement, and Concentrated Growth Factor (CGF), a second-generation autologous growth factor, on pulpotomy-induced pulp inflammation. The study utilized the maxillary anterior central teeth of thirty-six young male Sprague Dawley rats. Forty-eight teeth were randomly assigned to two groups (12 rats/group; 24 teeth/group) based on the capping material (MTA or CGF). Subsequently, two subgroups (MTAG and CGFG) were formed per group (12 teeth/group) based on the time following pulpotomy (2-weeks and 4-weeks). The central teeth of the 12 animals assigned to the control group (CG) were not manipulated in any way, both in the 2-week group and in the 4-week group. Tissue samples extracted from rats at the end of the experiment were stained with H&E for histopathological analysis. For immunohistochemical analysis, primary antibodies for TNF-α and NF-kß/65 were incubated. Data obtained from semi-quantitative analysis were assessed for normal distribution using Skewness-Kurtosis values, Q-Q plot, Levene's test, and the Shapiro-Wilk test on statistical software. A P value < 0.05 was considered significant. When compared with the control group, both MTAG and CGFG showed increased edematous and inflammatory areas. In MTAG, edematous and inflammatory areas decreased significantly from the 2nd week (2(2-2), 2(1-2)) to the 4th week (1(1-1), 1(0-1)), while in CGFG, edematous areas decreased (2(2-3), 1.5(1-2)), and inflammatory areas increased significantly (2(2-3), 3(2-2.5)). When compared with the control group, TNF-α and NF-kß/p65 positivity were higher in both MTAG and CGFG. In MTAG, TNF-α [2(1.5-2)] and NF-kß/p65 [1.5(1-2)] positivity decreased significantly from the 2nd week to the 4th week [TNF-α: 1(1-1), NF-kß/p65: 1(1-2)], while no significant change was observed in CGFG. In conclusion, this study revealed a reduction in cells showing TNF-α and NF-kß/p65 positivity in the MTA treatment group compared to the CGF group. Although MTA demonstrated more favorable results than CGF in mitigating pulpal inflammation within the scope of this study, further experimental and clinical investigations are warranted to obtain comprehensive data regarding CGF.

The effects of chlorhexidine gel and tranexamic acid application after tooth extraction on the risk of alveolar osteitis formation: a double blind clinical study.

BACKGROUND: Alveolar osteitis(AO), one of the most common complications occurring in 1-10% of cases following tooth extraction, occurs due to the disruption of clot formation in the extraction socket. This study aims to evaluate the effect of using absorbable gelatin sponge, chlorhexidine gel, and tranexamic acid agents on the development of AO following extraction. METHODS: Between March and October 2023, the teeth of 98 healthy patients (average age: 38, range: 19-62) with extraction indications were extracted at Recep Tayyip Erdogan University, Faculty of Dentistry, Department of Oral and Maxillofacial Surgery. 113 extraction sockets(85 molars and 28 premolars) were randomly treated with absorbable gelatin sponge(AGS), chlorhexidine gel with AGS, and tranexamic acid with AGS. Pain and edema levels were recorded using visual analog scale(VAS) ranging from 0 to 10 by the patients. Additionally, presence of halitosis, trismus and exposed bone was noted on forms on 3rd and 7th days (recorded as present or absent). The study prospectively aimed to prevent AO using 3 different dental agents in the extraction sockets. Statistical analyses of the study were conducted using the SPSS software package. RESULTS: Alveolitis was observed in 12 out of 113 tooth extractions(%10.6). Pain and edema scores significantly decreased in absorbable gelatin sponge group on the 7th day (p < 0.05). Pain score on the 7th day in chlorhexidine group and age, edema score on the 7th day in tranexamic acid group, were found to be significantly higher (p < 0.05). CONCLUSION: Incidence of AO, can be reduced by placing agents in the extraction socket, preventing post-extraction pain experienced by patients. CLINICAL TRIALS ID: NCT06435832.

Electrophysiological and histopathological evaluation of the effectiveness of melatonin and glatiramer acetate for traumatic facial nerve injuries.

AIM: This study aimed to evaluate the effect of systemic/local use of melatonin and glatiramer acetate on regeneration in traumatic nerve injury models. MATERIALS AND METHODS: A total of 42 male Wistar albino rats were randomly divided into 6 groups: healthy control (Group 1), injured control (Group 2), local melatonin (Group 3), systemic melatonin (Group 4), local glatiramer acetate (Group 5), and systemic glatiramer acetate (Group 6). In all groups, electromyography recordings of the facial nerve were obtained after surgery and before sacrifice, and the damaged nerve region was histopathologically examined after sacrifice. RESULTS: In the electrophysiological evaluation, the control group had the greatest decrease in amplitude and extension in latency time following surgery than the treatment groups. Furthermore, a significant decrease in the degenerative axon count, edematous areas, and fibrotic areas as well as a significant increase in axonal surface areas was observed in all the treatment groups compared with the damage control group. CONCLUSIONS: Although both glatiramer acetate and melatonin are beneficial in regeneration in traumatic facial nerve injuries, it can be concluded that systemic use of melatonin can yield more positive results than glatiramer acetate and local use of both two drugs.

Evaluation of Turkish dentists' knowledge about oral cancer and oral mucosal lesions.

BACKGROUND/PURPOSE: Oral cancer, including malignancies of the tongue, lips, floor of the mouth, cheek mucosa, gums, palate, and oropharynx, is life-threatening. Early diagnosis and appropriate treatment are crucial for long-term survival. Dentists frequently encounter oral cancers due to the nature of their work. This study aimed to evaluate the knowledge and experience of dentists in Turkey regarding oral cancers. MATERIALS AND METHODS: A total of 361 participants were included in the study, and survey questions were sent via email. The survey consisted of 16 questions measuring demographic data and knowledge about oral cancerous lesions. Participants were grouped based on their specialization and knowledge level, and differences in responses among groups were examined. RESULTS: Only 21.3% of the participants felt they had sufficient knowledge and experience about oral cancerous lesions. Overall, the correct answer rates indicated a moderate level of knowledge and experience. When grouped by specialization, oral surgeons had the highest accuracy in their responses (p < 0.05). CONCLUSION: Dentists are the professional group that most frequently encounters clinically oral cancerous lesions. Therefore, it is critically important for them to be knowledgeable and experienced to reduce morbidity and mortality through early diagnosis. This study evaluated the knowledge status of dentists in Turkey regarding oral cancer and highlighted the need for improved education.

Is there a relationship between third-molar impaction types and the dimensional/angular measurement values of posterior mandible according to Pell & Gregory/Winter Classification?

OBJECTIVE: The aim of this study was to examine the relationship between ramus height, gonial angle and impaction classifications of mandibular third molars. METHODS: A total of 829 mandibular third molars in 601 patient's orthopantomography (OPG) and cephalometric radiography records were evaluated. Gonial angle was measured on cephaloametric radiography and ramus height was measured on OPG. Impacted third molars were classified according to Pell & Gregory Vertical/Winter classification on OPG. The relationship between the impaction classifications and ramus height/gonial angle was evaluated. RESULTS: Statistically significant difference was found in Pell & Gregory Classification types in terms of ramus height/gonial angle (p < 0.001). Significant difference was found in terms of Gonial angle in Winter Classifications (p < 0.001). Ramus height was found to be lower than 3.8 cm in patients with an angle less than 123.8° (sensitivity 78%, specificity 84%). CONCLUSIONS: Correlation between ramus height/gonial angle and impaction classification types of mandibular third-molar teeth was detected.

Evaluation of sphenoid sinus variations by using cone beam computed tomography in patients with cleft lip/palate.

OBJECTIVE: The purpose of this study is to evaluate the sphenoid sinus variations in patients with cleft lip/palate. METHODS: Sixty three (63) patient's cone beam computed tomography (CBCT) images, taken from the head and neck region, were evaluated. Images were divided into two groups; [Group 1; patients with cleft lip/palate (CLP Group) (n = 23) Group 2; patients without cleft lip/palate (control group) (n = 40)]. The main pneumatization types (conchal, sellar, and presellar) of sphenoid sinuses were assessed on sagittal sections of the CBCT images. The sphenoid body, lateral and lesserwing types were evaluated on coronal sections and anterior type pneumatization was evaluated on axial sections. RESULTS: The mean age ranged from 12 to 26 (16.57 ± 4.46) in Group 1 and 12 to 25 (16.58 ± 3.71) in Group 2. In both groups, the male and female distribution was found similar (P = 0.342). The sellar type was the most common pneumatization type of sphenoid sinus both for the Group 1 (91.3%) and Group 2 (80%). Any statistically significant difference was not found between the two groups in terms of the incidence of pneumatization types. Combined type pneumatization was detected in 65.6% of the Control group and 76.2% of the CLP group. CONCLUSIONS: In this study, the prevalence of sphenoid sinus pneumatization types in CLP patients was compared with the normal population. Any significant difference was not determined in the two groups.

Effect of Root Resection Length and Graft Type Used After Apical Resection: A Finite Element Study.

PURPOSE: Apical resection is a surgical technique that involves removing a tooth's root tip and sealing the apical extent of the root canal system. However, evidence-based information on the biomechanical effects of apically resected tooth determinants is lacking. The aim of the present study was to examine the biomechanical effects of using different graft materials and the effect of different resection quantities on the tooth radix. MATERIALS AND METHODS: Thirty finite element models of mandibular central incisors with 1-cm defects in their apical regions were constructed using SolidWorks software (SolidWorks, Waltham, MA). Resections of 0, 1, 2, 3, 4, and 5 mm were created at the root tips, and tissue regeneration was simulated in the empty cavity models using the material properties of healed bone, an allograft, a xenograft, and hydroxyapatite to the grafts used to fill the apical sites. A 100-N force was applied to the various groups of teeth in the oblique (45°) direction, and the maximal von Mises stress and displacement values were determined using Ansys, version 16, software (ANSYS, Inc, Canonsburg, PA). RESULTS: The highest of these values was observed in the 5-mm resected and empty model. Increasing the resection amount caused the stress and displacement to increase. The lowest stress and deformation values were seen in the hydroxyapatite group, followed by the xenograft group and the allograft group. CONCLUSIONS: The results of the present study have shown that grafting into the apical defect provides biomechanical support for resection of the root structure.

Biomechanical Evaluation of Zygomatic Implant Use in Patients With Different Buccal Maxillary Defect Levels.

PURPOSE: The purpose of this study was to examine the biomechanics of zygomatic implants that were planned on an atrophic maxilla with five different buccal defect types and two different bone types. MATERIALS AND METHODS: Three-dimensional models of zygomatic implants, human skulls, and maxillary prostheses were modeled with SolidWorks software. Ten finite element models of skulls with five different buccal defect types and two different bone types were constructed to mimic various clinical scenarios. Two bilateral zygomatic implants and two anterior dental implants were inserted into all models. The data were processed by ANSYS Workbench software. 150-N vertical occlusal and 300-N masseteric loads were simulated on a modeled prosthesis. The stresses on and deformations of the bones and implants were then observed and compared. RESULTS: Maximum Von Mises stress was found in skulls modeled with a type 4 defect and D3 bone type. Minimal stress values were found in the skull model with a type 1 buccal bone defect and D2 bone type. Displacement values were correlated with stress values. CONCLUSION: Cortical bone anchorage and bone type of zygomatic implants positively affect their biomechanics. Alveolar crest support has an effective role in the biomechanics of zygomatic implants.

Influence of implant number, length, and tilting degree on stress distribution in atrophic maxilla: a finite element study.

This study aims to evaluate the stress values, created in peri-implant region as a consequence of loading on fixed hybrid dentures that was planned with different implant numbers, lengths, or tilting angulations. Thirteen three-dimensional (3D) finite element analysis models were generated with four, five, or seven implants (group A, B, and C). Except the distal implants, all implants were modeled at 4.1 mm (diameter) and 11.5 mm (length) in size. Distal implants were configured to be in five different lengths (6, 8, 11.5, 13, and 16 mm) and three different implant inclination degrees (0°, 30°, and 45°). A 150-N load was applied vertically on prosthesis. Released stresses were evaluated comparatively. The lowest von Mises stress values were found in group C, in the 11.5-mm implant model. Tilting the distal implants 30° caused higher stress values. In 45°-tilting implant models, lower stress values were recorded according to the 30°-tilting models. The ideal implant number is seven for an edentulous maxilla. Tilting the implants causes higher stress values. A 45° inclination of implant causes lower stress values according to the 30° models due to a shorter cantilever. The ideal implant length is 11.5 mm.

Biomechanical evaluation of implant-supported prosthesis with various tilting implant angles and bone types in atrophic maxilla: A finite element study.

BACKGROUND AND OBJECTIVE: The purpose of this study is to evaluate and compare bone stress that occurs as a result of using vertical implants with simultaneous sinus augmentation with bone stress generated from oblique implants without sinus augmentation in atrophic maxilla. METHODS: Six, three-dimensional (3D) finite element (FE) models of atrophic maxilla were generated with SolidWorks software. The maxilla models were varied for two different bone types. Models 2a, 2b and 2c represent maxilla models with D2 bone type. Models 3a, 3b and 3c represent maxilla models with D3 bone type. Five implants were embedded in each model with different configurations for vertical implant insertion with sinus augmentation: Model 2a/Model 3a, 30° tilted insertion; Model 2b/Model 3b and 45° tilted insertion; Model 2c/Model 3c. A 150 N load was applied obliquely on the hybrid prosthesis. The maximum von Mises stress values were comparatively evaluated using color scales. RESULTS: The von Mises stress values predicted by the FE models were higher for all D3 bone models in both cortical and cancellous bone. For the vertical implant models, lower stress values were found in cortical bone. Tilting of the distal implants by 30° increased the stress in the cortical layer compared to vertical implant models. Tilting of the distal implant by 45° decreased the stress in the cortical bone compared to the 30° models, but higher stress values were detected in the 45° models compared to the vertical implant models. CONCLUSIONS: Augmentation should be the first treatment option in atrophic maxilla in terms of biomechanics. Tilted posterior implants can create higher stress values than vertical posterior implants. During tilting implant planning, the use of a 45° tilted implant results in better biomechanical performance in peri-implant bone than 30° tilted implant due to the decrease in cantilever length.