Erich arch bars vs intermaxillary fixation screws for mandibular fracture reduction during ORIF: a randomized clinical trial.

OBJECTIVE: This randomized clinical trial aimed to compare the efficacy of Erich arch bars (EAB) and intermaxillary fixation (IMF) screws in reducing mandibular fractures during open reduction and internal fixation (ORIF). METHODS: A total of 28 patients with mandibular fractures were randomly allocated to either the EAB group or the IMF screws group. The study evaluated various parameters including occlusal stability, complications, duration of application, oral hygiene status, quality of life, and patient characteristics. RESULTS: The study found no significant differences in occlusal stability between the EAB and IMF screw groups. However, the application and removal times were longer for EAB compared to IMF screws. The EAB group showed a higher presence of biofilm on teeth, indicating poorer oral hygiene status compared to the IMF screws group. In terms of quality of life, patients in the EAB group reported worse results in the "handicap" domain at the 15th postoperative day. No significant differences were observed in other quality-of-life parameters. Patient characteristics were well distributed between the two groups, enhancing the reliability of the results. CONCLUSION: Both EAB and IMF screws demonstrated comparable occlusal stability for minimally displaced mandibular fractures. However, IMF screws offered advantages such as shorter application and removal times, better oral hygiene maintenance, and potentially improved quality of life in the "handicap" domain. Further studies with larger sample sizes are necessary to validate these findings and explore the stability of IMF methods in cases requiring postoperative malocclusion correction or prolonged IMF.

Manual versus rigid intraoperative maxillo-mandibular fixation in the surgical management of mandibular fractures: A European prospective analysis.

PURPOSE: Intraoperative stabilisation of bony fragments with maxillo-mandibular fixation (MMF) is an essential step in the surgical treatment of mandibular fractures that are treated with open reduction and internal fixation (ORIF). The MMF can be performed with or without wire-based methods, rigid or manual MMF, respectively. The aim of this study was to compare the use of manual versus rigid MMF, in terms of occlusal outcomes and infective complications. MATERIALS AND METHODS: This multi-centric prospective study involved 12 European maxillofacial centres and included adult patients (age ≥16 years) with mandibular fractures treated with ORIF. The following data were collected: age, gender, pre-trauma dental status (dentate or partially dentate), cause of injury, fracture site, associated facial fractures, surgical approach, modality of intraoperative MMF (manual or rigid), outcome (minor/major malocclusions and infective complications) and revision surgeries. The main outcome was malocclusion at 6 weeks after surgery. RESULTS: Between May 1, 2021 and April 30, 2022, 319 patients-257 males and 62 females (median age, 28 years)-with mandibular fractures (185 single, 116 double and 18 triple fractures) were hospitalised and treated with ORIF. Intraoperative MMF was performed manually on 112 (35%) patients and with rigid MMF on 207 (65%) patients. The study variables did not differ significantly between the two groups, except for age. Minor occlusion disturbances were observed in 4 (3.6%) patients in the manual MMF group and in 10 (4.8%) patients in the rigid MMF group (p > .05). In the rigid MMF group, only one case of major malocclusion required a revision surgery. Infective complications involved 3.6% and 5.8% of patients in the manual and rigid MMF group, respectively (p > .05). CONCLUSION: Intraoperative MMF was performed manually in nearly one third of the patients, with wide variability among the centres and no difference observed in terms of number, site and displacement of fractures. No significant difference was found in terms of postoperative malocclusion among patients treated with manual or rigid MMF. This suggests that both techniques were equally effective in providing intraoperative MMF.

Predictability of the virtual surgical plan for orthognathic surgery with the mandible surgery first sequence.

The aim of this study was to compare the virtually planned position to the postoperative position of the maxilla, having performed the maxilla-first sequence or mandible-first sequence orthognathic surgery. An audit of 64 patients who underwent bimaxillary surgery between 2017 and 2020 was performed. Thirty patients had maxilla-first surgery and 34 had mandible-first surgery. The planned and post-surgical positions were analyzed using specific skeletal landmarks. Differences were calculated and the two-sample t-test was used to compare the groups. Measured differences between the planned and postoperative results differed significantly between the mandible-first and maxillary-first surgery groups (P < 0.001). The maxillary central incisors were under-advanced in the anterior-posterior direction in both groups. Most data points showed deviation from the surgical plan ≤ 2 mm and ≤ 4°. Secondarily, maxillary under-advancement in the mandible-first cohort was evaluated; these patients were subdivided into rigid and non-rigid fixation groups. The non-rigid fixation group showed less accuracy compared to the rigid fixation group, which was statistically significant (P = 0.014). The findings of this study demonstrate that virtual surgical planning can be less accurate in predicting the maxillary incisor position when performing mandible-first surgery, but this inaccuracy is within the acceptable range and can be mitigated by rigid fixation of the mandible.

Mini - Retromandibular access to sub condylar mandibular fractures - Our experience.

Condylar fractures alone accounts to about 25% to 40% of all the fractures of mandible. Management of condylar fractures has always been a controversy. Nowadays there has been more emphasis on open reduction of condylar fractures by the surgeons.The reasons could be the result of complications of closed reduction where the patient may not be able to masticate properly and deviation still present thereby the structural and functional loss forcing the surgeons' choice to open up. The anterior parotid approach has lesser risk of injury to parotid gland and also to facial nerve we attempted to use mini retro mandibular access for such fractures. So the aim was to explore the feasibility of the mini retro mandibular approach to sub condylar fractures. The patients reported to the department of oral and maxillofacial surgery department clinically and radio logically diagnosed and treated for condylar fractures were included. The maximal mouth opening, protrusive and lateral excursive movements, midline orientation with opposing arch, scar visibility, sialocele and facial nerve weakness were all recorded post operatively and compared with pre-operative recording. The mini retro mandibular access with anterior parotid transmessetric approach to sub condylar fractures can be the choice for the surgical management of sub condylar fractures which is absolutely easy, reliable, with less visible scar and with less chances of landing in facial nerve complications.

Comparison of intermaxillary fixation techniques for mandibular fractures with focus on patient experience.

BACKGROUND: Intermaxillary fixation (IMF) is a technique that allows for the reduction and stabilization of mandibular fractures. Several methods of IMF, such as self-tapping screws or arch bars, have been developed. This study aimed to validate the usefulness of IMF with a self-tapping screw compared to IMF with arch bars with focus on the patients' perspective. METHODS: We retrospectively reviewed the medical records of all patients who were treated for mandibular fractures at our hospital between August 2014 and February 2021. A total of 57 patients were enrolled in this study. Thirteen patients were excluded from the analysis: three patients were lost to follow-up, and 10 patients did not undergo IMF. Finally, 44 patients were analyzed, of which 31 belonged to the arch bar group, and 13 belonged to the screw group. Patient discomfort and pain during IMF application and removal were analyzed using a patient self-assessment questionnaire. The surgeon also assessed oral hygiene, IMF stability, and occlusion. RESULTS: We applied IMF to 34 men (77%) and 10 women (23%). The mean age of the patients was 37.3 years. The most common fracture site was the angle (30%), followed by the parasymphysis (25%), the body (23%), the condyle (11%), and the ramus (11%). Patient discomfort and oral hygiene were statistically favorable in the screw group. The IMF application time was statistically shorter in the screw group (p< 0.001). IMF stability was not statistically different between the two groups. The pain score during IMF removal was lower in the screw group (p< 0.001). CONCLUSION: Compared to arch bars, IMF screws provide more comfort during the IMF period, help maintain favorable oral hygiene, and have a shorter application time. From the patient's perspective, IMF screws are an excellent alternative to conventional arch bars when applicable.

Penetration of inferior alveolar nerve canal increased by bicortical fixation after bilateral sagittal split osteotomy in mandibular prognathism.

The purpose of this three-dimensional cone beam computed tomography (CBCT) study was to identify the difference between monocortical fixation (MCF) and bicortical fixation (BCF) in mandibular canal penetration after bilateral sagittal split osteotomy (BSSO) to correct mandibular prognathism, where interosseous fixation was done by BCF or MCF. CBCT was performed 1 week postoperatively and Dolphin 3D software was used to assess direct penetration of the mandibular canal by either type of screw. The primary outcome variable was the presence or absence of mandibular canal penetration and was categorized as a binary coded variable. The BCF and MCF groups were compared by χ2 test, and the odds ratio for canal penetration was estimated. Multiple logistic regression was performed to identify factors related to canal penetration. A total of 118 patients were included. The MCF group had only 6% canal penetrations (3/50 patients) and the BCF group had 58.8% canal penetrations (40/68 patients). The regression model showed that BCF was the only factor causing mandibular canal penetration, with an adjusted odds ratio of 52.5. Awareness of the increased risk of canal penetration with BCF and potential nerve injury might influence case selection.

Stability of fixation methods in large mandibular advancements after sagittal split ramus osteotomy: an in vitro biomechanical study.

Sagittal split ramus osteotomy (SSRO) with large mandibular advancements is a common surgical procedure and could be indicated for patients with sleep apnoea. As a large variety of fixation methods is used for the stabilisation of SSRO, a biomechanical test model was used to analyse which fixation technique was most stable. For this in vitro study, 80 polyurethane hemimandibles with a prefabricated SSRO were used as substrates. Loads in Newtons were recorded at displacements of the mandibular incisive edge at 1mm, 3mm and 5mm. The samples were divided into two groups: mandibular advancements of 10mm and 15mm. In both groups, four fixation techniques were used: (A) one four-hole miniplate; (B) two four-hole miniplates; (C) one four-hole miniplate plus one bicortical screw; and (D) three bicortical screws in an inverted-L arrangement. In group 1, three bicortical screws resulted in the best stability, and in group 2, two miniplates resulted in the best stability. The use of two miniplates did not show significant differences between both groups. Other fixation methods showed more stability with 10mm advancements. This study therefore suggests that in SSRO with advancements exceeding 10mm, the use of two miniplates is the optimal means of providing rigid fixation.

Tomographic analysis of nasomaxillary and zygomaticomaxillary buttress bone thickness for the fixation of miniplates.

The purpose of this study was to evaluate the bone thickness of the nasomaxillary and zygomaticomaxillary buttresses to identify the most favourable region for the installation of miniplates. Bilateral tomographic images of 103 individuals were evaluated, for a total of 206 nasomaxillary and zygomaticomaxillary buttresses. Measurements of bone thickness were performed in the parasagittal reconstructions along three vertical lines on the nasomaxillary buttress (21 measurement points) and four vertical lines on the zygomaticomaxillary buttress (28 measurement points). The vertical line measurements for each buttress were compared using the Kruskal-Wallis test. Spearman's correlation coefficient was used to determine the correlation between the thicknesses obtained and patient sex and side (right/left). The level of significance adopted was 5%. The nasomaxillary and zygomaticomaxillary buttresses presented statistical differences in thickness at their respective points (P=0.001). The analysis of the nasomaxillary buttress showed that the thicker bone for the installation of miniplates follows the long axis of the upper canine at a distance of 3mm from the root apex. For the zygomaticomaxillary buttress, thicker bone to install miniplates was found distal to the distobuccal root of the first molar, at a distance of 3.5mm from the limit of the infraorbital foramen.

Zygomaticomaxillary complex fracture after two-jaw surgery.

Orthognathic surgeries often utilize rigid fixation for stabilization of the osteotomy site. The longterm fate of rigid fixations is still under investigation, and whether they should be routinely removed is under debate despite their low complication rates. Here, we report a case where a 26-year-old man suffered high-velocity trauma to his face 7 years after a two-jaw surgery. Computed tomography examination revealed a zygomaticomaxillary complex fracture, and open reduction and internal fixation was performed along with anterior maxillary wall reconstruction using absorbable mesh. Intraoperative examination revealed a broken L-shaped titanium plate near the fracture site with multiple bony fragments near each titanium screw. The rigid titanium system may have caused comminution of the fracture pattern, worsening the severity of the fracture.

Fixação funcionalmente estável no tratamento de sequela de fratura cominutiva de mandíbula por PAF / Functionally stable fixation in the treatment of comminuted jaw fracture by firearm projectile

Introdução: em traumas de alta energia por projéteis de arma de fogo (PAF), pode ocorrer a cominuição da mandíbula. Quando não identificadas ou tratadas de maneira equivocada, essas injúrias podem comprometer a saúde do indivíduo, com graves complicações estéticas e funcionais. Objetivo: o objetivo deste trabalho é relatar um caso de tratamento cirúrgico de sequela de ferimento por arma de fogo com fratura cominutiva em região de sínfise mandibular. Relato do caso: paciente procurou o serviço de cirurgia e traumatologia bucomaxilofacial após tratamento cirúrgico insatisfatório de fratura mandibular por PAF. Observou-se clinicamente mobilidade em manipulação, exposição óssea e drenagem purulenta. Na tomografia, observou-se gap ósseo, descontinuidade na base mandibular e material de osteossíntese inadequado. Foi proposta uma abordagem cirúrgica para instalação de placa de reconstrução do sistema 2.4 mm. Em acompanhamento pós-operatório, o paciente evoluiu com abertura bucal funcional e satisfatória, sem mobilidade nos fragmentos ósseos, arcabouço mandibular restabelecido e adequado posicionamento do material de fixação. Considerações finais: os casos de cominuição óssea apresentam características individuais que devem ser levadas em consideração em seu manejo. Nesses casos, a escolha do material de fixação é fundamental para o sucesso terapêutico e o uso de prototipagem soma para uma condução satisfatória do caso, garantindo menor tempo cirúrgico e melhor adaptação da placa. (AU)

Introduction: in high energy traumas caused by firearm projectiles may occur comminutive mandibular fractures. When it is not identified or inappropriately treated, these injuries can compromisse the individual's health, with serious aesthetics and funcional complications. Objective: the aim of this study is report a case of surgical treatment of sequelae from firearm injury with comminutive fracture in the region of mandibular symphysis. Case report: patient sought the service of Oral and Maxillofacial Surgery and Traumatology after 1 month of unsatisfactory surgical treatment of a mandibular fracture caused by firearm projectile. Clinical examination revealed mobility to manipulation and bone exposure with purulent drainage. Computed tomography of the face shows bad fracture consolidation in the anterior region of the mandible with bone gap and discontinuity in the mandibular base and inadequate and poorly positioned osteosynthesis material. It was then proposed a new surgical approach with instalation of the reconstruction plate of 2.4mm locking system. In postoperative follow-up, the patient evolved with a functional and satisfactory mouth opening, with no mobility in bone fragments, restored mandibular framework and adequate positioning of the fixation material. Final considerations: the cases of comminutive bone fractures show particular features that should be considered in their handling. In these cases, the choice of the fixation material is critical to therapeutic success and the use of prototyping sum for a satisfactory conduction of the case, ensuring shorter surgical time and better adaptation of the plate.(AU)

Atrophic jaw fracture and predictability in oral rehabilitation: case report / Fratura de mandíbula atrófica e previsibilidade na reabilitação oral: relato de caso

Introduction: The treatment of atrophic jaw fractures requires extensive knowledge by the maxillofacial surgeon. The correct diagnosis and planning optimize the possibility of oral rehabilitation towards many possible alternatives. The difficulty in repairing these fractures makes the treatment complex, in which normally invasive techniques are used. However; which give us satisfactory and predictable aesthetic-functional results. Objective: The objective of this work is to report an atrophic jaw fracture and posterior dental implants re-habilitation. Case report: A 53 years old female patient, victim of in face aggression referred to the emergency care. At the clinical examination, the patient had laceration in the upper lip region and the left side of the mandibular area, with bilateral mobility and paresis. In the oral examination, total lower and partial upper edentulism. After tomographic evaluation, a bilateral fracture of the mandibular body was confirmed, with significant bone fragments uneven. Surgery was performed with total transcervical access and use of reconstruction plate. After 90 days of follow-up, the oral rehabilitation with osseointegrated implants was performed. Conclusion: Complex atrophic mandible fractures in total edentulous patients can be treated with open reduction and stable fixation, allowing a faster return to normal function, improve of quality of life and assists in increasing safety for implant installation (AU)

Introdução: O tratamento de fraturas em mandíbula atrófica requer amplo conhecimento por parte da cirurgião bucomaxilofacial. O correto diagnóstico e planejamento otimizam a possibilidade de reabilitação, diante das muitas alternativas possíveis. A dificuldade em reparar essas fraturas torna o tratamento complexo, no qual normalmente técnicas invasivas são usadas. Entretanto, é possível alcançar resultados funcionais e estéticos satisfatórios e previsíveis. Objetivo: O objetivo de este trabalho é relatar uma fratura em mandíbula atrófica seguida de reabilitação com implantes dentários em região posterior. Relato de caso: Paciente do sexo feminino, 53 anos, vítima de agressão em face buscou o serviço de emergência. No exame clínico, observou-se laceração na região do lábio superior esquerdo com mobilidade bilateral e paralisia em região mandibular. No exame intra-oral, edentulismo total inferior e parcial superior. Após avaliação tomográfica, a fratura bilateral do corpo mandibular foi confirmada, com presença de significativos fragmentos ósseos. A cirurgia foi realizada com acesso transcervical total e uso de placa de reconstrução. Após 90 dias de acompanhamento foi iniciada a etapa de reabilitação oral com implantes osseointegrados. Conclusão: Fraturas atróficas complexas da mandíbula em pacientes desdentados totais podem ser tratados com redução e fixação estável, permitindo um rápido retorno da função, melhora da qualidade de vida, além de auxiliar no aumento da segurança no momento da instalação dos implantes (AU)

A prospective comparative clinical study on modified screw retained arch bar (SRAB) and conventional Erich's arch bar (CEAB).

INTRODUCTION: Intermaxillary fixation (IMF) is commonly performed in the management of facial skeleton fractures. Various conventional methods like Erich's arch bar and Ivy eyelet wiring are the most commonly employed methods for achieving IMF, but they have their own disadvantages. Conventional Erich's arch bar (CEAB) has been modified recently by making perforations in the spaces between the winglets and securing the arch bar using 1 mm screws. IMF using intraoral modified screw retained arch bar (SRAB) has been introduced for the treatment of mandibular fractures. The aim of this study was to compare the efficacy, advantages, disadvantages, indications, and potential complications associated with CEAB versus modified SRAB in the management of mandibular fractures. MATERIALS AND METHODS: A randomized prospective study included 20 patients with mandibular fracture who were randomly allotted to two groups. Group A patients received modified SRAB and group B patients received CEAB. The parameters considered were time taken to place the arch bar, perforation in the gloves, patient acceptance, oral hygiene, iatrogenic dental injuries, and needle (wire) stick injuries during IMF. RESULTS: The mean time taken for arch bar placement was 27.20 min with modified SRAB as compared with 82.50 min with CEAB. Incidence of glove perforations was more in group B patients. Oral hygiene status was good in 90% of the patients from group A whereas it was 100% fair in group B patients. CONCLUSION: This study has shown that both the techniques achieve satisfactory IMF with post-operative occlusion. IMF with modified SRAB reduces the operating time and the incidence of the needle (wire) prick injuries. But modified SRAB has its own limitations in spite of its ease of application.

Patient-specific 3D printed plates improve stability of Le Fort 1 osteotomies in vitro.

PURPOSE: Selective laser melting used to manufacture patient-specific 3D-printed (PSP) plates is a delicate process, which may introduce weakened areas in the plates, with risk of fracture. This in vitro study's purpose was to test the ability of PSP plates to stabilize Le Fort I osteotomies compared with manually adapted stock plates. The study's objectives were to measure the force needed to compress the osteotomy and evaluate whether the PSP plates would break during compression. MATERIALS AND METHODS: This controlled in vitro study evaluated the maxillary stability using the clinical data from 7 patients. The virtually planned maxillary reposition was 3D-printed in 2 copies, and the osteotomy gap was fixated by either PSP plates or stock plates. The models were compressed until the Le Fort I osteotomy gap was eliminated. The primary outcome was the force needed to compress the model. The primary predictor variable was a comparison between PSP and stock plates. Secondary outcome measurements were the slope of elastic modulus, yield point, and force needed for 2 mm compression. Statistical testing was performed by Wilcoxon signed-rank test with significance level at P ≤ 0.05. RESULTS: The PSP plates performed better than stock plates in all outcome measurements. None of the plates broke during compression despite forces of more than 4000 N. The first point of failure in PSP plates was the first screw cranial to the osteotomy. In comparison, the first point of failure in stock plates was in the plates' bend at the osteotomy. CONCLUSION: In this in vitro setup, the Le Fort I osteotomies fixated with PSP plates were more stable than the osteotomies fixated with conventional stock plates. No adverse effects occurred during testing of PSP plates; thus, PSP plates seem to be a safe alternative to stock plates and may even be preferable.

Fixation methods in sagittal split ramus osteotomy: a systematic review on in vitro biomechanical assessments.

The aim of this systematic review was to assess the stability of rigid internal fixation (RIF) techniques in sagittal split ramus osteotomy (SSRO) based on in vitro biomechanical assessments, with particular interest in large mandibular advancements. In general, RIF methods can be divided into three groups: bicortical screws, miniplates, and a combination of the two. An electronic search of the PubMed, CINAHL, and Embase databases was performed, and studies published between January 2003 and March 2018 were screened for inclusion. Comparative studies with an in vitro experimental design, using biomechanical assessments to measure the stability of RIF methods in SSRO, were included. Of 104 unique studies identified in the initial search, 24 were included. Twenty-two of these 24 studies analyzed an advancement of the mandible of 7mm or less. The use of a single four-hole or six-hole miniplate was less stable than the use of bicortical screws, hybrid techniques, double miniplates, or grid plates. Two studies analyzed advancements of 10mm, for which two miniplates placed in parallel and a grid plate showed most stability. Although there was agreement between studies with regard to results, more biomechanical studies are required to quantify the stability of fixation methods in larger mandibular advancements.

Reabilitação de fratura complexa de mandíbula atrófica com placa tipo locking ­ relato de caso / Atrophic mandible complex fracture rehabilitation with locking type plate ­ case report

A atrofia óssea devido a perdas dentárias ocasiona diminuição da altura e espessura do reordo, tornando a mandíbula susceptível a fraturas. Pode-se considerar atrófica, quando a altura óssea não ultrapassa 20 mm. Essas fraturas acometem principalmente a população idosa, porque além da atrofia óssea subsequente ao edentulismo, a redução da vascularização contribui para o enfraquecimento da mandíbula nos pacientes desse grupo etário. O tratamento dessas fraturas permanece um desafio cirúrgico e não há consenso quanto à melhor técnica de tratamento. Isso devido a fatores inerentes a essa patologia, a relativa raridade da mesma, o que gera inexperiência dos cirurgiões e a escassez de informação sobre o tema na literatura cirúrgica. O objetivo deste trabalho consiste em descrever um caso de tratamento de fratura em mandíbula atrófica, no qual foi realizada a correção cirúrgica da fratura através da técnica de redução aberta com acesso intrabucal que se estendeu da região retromolar direita à mesma região contralateral e de segmentos ósseos fixados com uma placa de reconstrução do sistema 2.0 mm, tipo locking e parafusos bicorticais (AU).

Bone atrophy due to tooth loss causes a decrease in bone height and thickness, making jaw susceptible to fractures. It can be considered atrophic when the bone height does not exceed 20 mm. These fractures mainly occlude the elderly population, because in addition to bone atrophy subsequent to edentulism, the reduction of vascularization contributed to mandible weakening in the patients of this age group. The treatment of these fractures remains a surgical challenge and there is no consensus in relation to the best treatment technique. This is due to factors inherent to this pathology, its relative rarity, which generates surgeon's inexperience, and scarcity of information on the subject in surgical literature. The aim of this work is to describe a clinic case of fracture treatment in an atrophic mandible, in which surgical fracture correction was performed through the technique of open reduction and intrabuccal access that extended from the right retromolar region to the same contralateral region and the bone segments fixed with a 2.0mm system rebuilding plate, locking type and bicortical screws (AU).

How to produce pre-shaped rigid arch bars using low-cost 3D printing technology - A technical note.

Numerous oral and maxillofacial procedures in dentate patients begin with the fixation of occlusions. While several techniques exist to perform mandibulo-maxillary fixation, many surgeons use arch bars in common practice. In cases of severe craniofacial traumas or jaw malformations, such as temporomandibular joint ankylosis, it may be impossible to use rigid arch bars. This technical note reports on the development of a technique to produce pre-shaped rigid arch bars using 3D printing technology. We take the case of a patient who presents Le Fort 1, Le Fort 2 and Le Fort 3 fractures as well as a central palatine disjunction, an angular mandibular fracture and bilateral zygomatic fractures. We specify the indications and limitations of this technique.

Mechanical evaluation of the use of conventional and locking miniplate/screw systems used in sagittal split ramus osteotomy.

OBJECTIVES: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. MATERIALS AND METHODS: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. RESULTS: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance (162.72±42.55 N), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. CONCLUSION: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

Mechanical evaluation of the use of conventional and locking miniplate/screw systems used in sagittal split ramus osteotomy

OBJECTIVES: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. MATERIALS AND METHODS: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. RESULTS: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance (162.72±42.55 N), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. CONCLUSION: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

Análise por Elementos Finitos das Forças Mastigatórias em uma Placa de Reconstrução Mandibular / Assessment of masticatory forces in a mandibular reconstruction titanium plate through finite element analysis

Ressecção cirúrgica é um tratamento radical de algumas patologias que acometem a mandíbula e suas estruturas associadas. A técnica baseia-se na remoção total da lesão com uma margem de segurança em toda a sua dimensão, podendo ser ela marginal ou parcial. A escolha dá-se pela proximidade da extensão da lesão com a margem inferior da mandíbula. Em situações de ressecção mandibular parcial, remove-se parcialmente a margem inferior da mandíbula o que, posteriormente, dificulta a reobtenção da estética e funcionalidade do aparelho estomatognático, sendo a área reconstruída com uma placa de reconstrução óssea. A análise de elementos finitos (AEF) é uma forma de análise matemática, que se fundamenta na divisão de uma estrutura em um número finito de pequenas áreas, denominado de elementos finitos. A essa divisão dá se o nome de "malha". Em geral, a AEF possui a capacidade de modelar matematicamente estruturas, tornando-se possível a aplicação de forças em qualquer ponto e/ou direção. Dessa forma, conseguem-se dados sobre a deformação e o grau de tensão inicial, sendo possível, assim, representar situações in vivo, expressando condições compatíveis com o real. O trabalho visa analisar e simular as tensões geradas pelas forças mastigatórias, com o uso de elementos finitos, em simulação de uma mandíbula reconstruída com placa e parafusos de titânio, após sua ressecção parcial... (AU)

Surgical ressection is a radical treatment of some pathologies that affect the mandible and its structures. The technique is based on total removal of the lesion with a safe margin in all extension of the bone. Partial mandible resection results in a difficult to obtain the aesthetic and functionality of the stomatognathic system. In such cases, is recommended a titanium plate commonly used to mandibular reconstruction. Finite Element Analysis (FEA) is a form of math analysis which is based on division of a structure in a finite number of small areas. In general, FEA has the ability to mathematically model structures making possible applying forces in any point and/ or direction. Thereby, it can bring forth datas of displacement and tension being possible representing in vivo situation. This study aims to analyze and simulate the tensions generated by the masticatory forces, using FEA in a mandibular reconstruction with titanium plate after partial resection... (AU)