Accuracy evaluation of a new three-dimensional reproduction method of edentulous dental casts, and wax occlusion rims with jaw relation

The article introduces a new method for three-dimensional reproduction of edentulous dental casts,and wax occlusion rims with jaw relation by using a commercial high-speed line laser scanner and reverse engineering software and evaluates the method’s accuracy in vitro.The method comprises three main steps：（i）acquisition of the three-dimensional stereolithography data of maxillary and mandibular edentulous dental casts and wax occlusion rims;（ii）acquisition of the three-dimensional stereolithography data of jaw relations;and（iii）registration of these data with the reverse engineering software and completing reconstruction.To evaluate the accuracy of this method,dental casts and wax occlusion rims of 10 edentulous patients were used.The lengths of eight lines between common anatomic landmarks were measured directly on the casts and occlusion rims by using a vernier caliper and on the three-dimensional computerized images by using the software measurement tool.The direct data were considered as the true values.The paired-samples t-test was used for statistical analysis.The mean differences between the direct and the computerized measurements were mostly less than 0.04 mm and were not significant（P.0.05）.Statistical significance among 10 patients was assessed using one-way analysis of variance（P,0.05）.The result showed that the 10 patients were considered statistically no significant.Therefore,accurate three-dimensional reproduction of the edentulous dental casts,wax occlusion rims,and jaw relations was achieved.The proposed method enables the visualization of occlusion from different views and would help to meet the demand for the computer-aided design of removable complete dentures.

Posterior partially edentulous jaws, planning a rehabilitation with dental implants

AIM: To discuss important characteristics of the useof dental implants in posterior quadrants and the rehabilitation planning. METHODS: An electronic search of English articles was conducted on MEDLINE(PubM ed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review. RESULTS: One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations(bone quantity and density), radiographic techniques, implant selection(number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters. CONCLUSION: The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning.

Prevalence and Risk Factors of Osteonecrosis of the Jaw in Patients with Bisphosphonate Exposure in Casablanca, Morocco: An Observational Study

Objective: To study the prevalence of bisphosphonate-related osteonecrosis of the jaw (BRONJ) and to determine the risk factors associated with the occurrence of this pathology. Method: An observational retrospective study was conducted in the Department of Oncology, Rheumatology, and Maxillofacial Surgery of Ibn Rochd University Hospital, Casablanca. The study utilized complete medical records from 2014 to 2022 and included consultations of patients receiving bisphosphonates (BPs) in July and September 2022. Statistical analysis was performed using SPSS version 16.0. Results: Our study population comprised 104 patients, of whom 91% were women and 49% were over 65 years old. Seventy-two percent of patients had a general pathology. Among them, 64 patients were treated with zoledronate, 43 with alendronate, and the remainder with risedronate, ibandronate, and pamidronate. The most common indications for treatment were bone metastasis following breast cancer (29.8%) and osteoporotic fractures (19.2%). Sixty-seven patients received intravenous (IV) treatment;only 10.5% exhibited good oral health. Fifty percent of patients underwent dental treatment, primarily tooth extractions. Osteonecrosis of the jaw (ONJ) was diagnosed in 1.9% of patients, predominantly in stages 1 and 2. Conclusion: Second and third-generation bisphosphonates are more strongly associated with the development of ONJ. Risk factors include monthly IV administration, poor oral health, comorbidities such as diabetes, medications like corticosteroids, invasive dental procedures, and not only oncological conditions but also rare indications such as bone algodystrophy. Nevertheless, our observed prevalence of 1.9% aligns with international rates ranging from 0.8% to 12%. However, most of the studies that have been carried out have been retrospective studies with insufficient numbers of patients. Further prospective epidemiological studies based on standardized protocols with rigorous and appropriate follow-up over several years are essential to determine the exact prevalence of ONJ.

Study on recovery of combined defects including edentulous jaw,zygoma and orbit defects

Objective The magnetic retainer was used to respair combined defects including edentous jaw,zygoma and orbit defects to recover patients mastication,language and swallow functions.Method Impression models of jaw,zygoma and orbit were taken.Two prosthesis were connected by magnetic retainer.Result Fixation,and recovery of language and face shape were favorable for patients with magnetic retainer.Mastitating function was completely recovered in health side and partially in affected side.Conclusion The magnetic retainer provide sufficient retention and reliable connection.It can recover mastication with convenient wearing and taking.

Kinematics ofmandibular advancement devices(MADs):Why do some MADs move the lower jaw backward duringmouth opening?

Mandibular advancement devices(MADs)are widely used treatments for obstructive sleep apnea.MADs function by advancing the lower jaw to open the upper airway.To increase patient comfort,most patients allow the mouth to be opened.However,not all systems maintain the lower jaw in a forward position during mouth opening,which results in the production of a retrusion that favors the collapse of the upper airway.Furthermore,the kinematic behavior of the mechanism formed by the mandible-device assembly depends on jaw morphology.This means that,during mouth opening,some devices cause lower jaw protrusion in some patients,but cause its retraction in others.In this study,we report the behavior of well-known devices currently on themarket.To do so,we developed a kinematic model of the lower jawdevice assembly.Thismodelwas validated for all devices analyzed using a high-resolution camera system.Our results show that some of the devices analyzed here did not produce the correct behavior during patient mouth opening.

Imaging approach for jaw and maxillofacial bone tumors with updates from the 2022 World Health Organization classification

Jaw and maxillofacial bone lesions encompass a wide variety of both neoplastic and non-neoplastic pathologies.These lesions can arise from various tissues,including bone,cartilage,and soft tissue,each presenting distinct challenges in diagnosis and treatment.While some pathologies exhibit characteristic imaging features that aid in diagnosis,many others are nonspecific.This overlap often necessitates a multimodal imaging approach,combining techniques such as radiographs,computed tomography,and magnetic resonance imaging to achieve a diagnosis or narrow the diagnostic considerations.This article provides a comprehensive review of the imaging approach to jaw and maxillofacial bone tumors,including updates on the 2022 World Health Organization classification of these tumors.The relevant anatomy of the jaw and dental structures that is important for accurate imaging interpretation is discussed.

Characterization of tumors of jaw:Additive value of contrast enhancement and dual-energy computed tomography

BACKGROUND Currently,the differentiation of jaw tumors is mainly based on the lesion’s morphology rather than the enhancement characteristics,which are important in the differentiation of neoplasms across the body.There is a paucity of literature on the enhancement characteristics of jaw tumors.This is mainly because,even though computed tomography(CT)is used to evaluate these lesions,they are often imaged without intravenous contrast.This study hypothesised that the enhancement characteristics of the solid component of jaw tumors can aid in the differentiation of these lesions in addition to their morphology by dual-energy CT,therefore improving the ability to differentiate between various pathologies.AIM To evaluate the role of contrast enhancement and dual-energy quantitative parameters in CT in the differentiation of jaw tumors.METHODS Fifty-seven patients with jaw tumors underwent contrast-enhanced dual-energy CT.Morphological analysis of the tumor,including the enhancing solid component,was done,followed by quantitative analysis of iodine concentration(IC),water concentration(WC),HU,and normalized IC.The study population was divided into four subgroups based on histopathological analysis-central giant cell granuloma(CGCG),ameloblastoma,odontogenic keratocyst(OKC),and other jaw tumors.A one-way ANOVA test for parametric variables and the Kruskal-Wallis test for nonparametric variables were used.If significant differences were found,a series of independent t-tests or Mann-Whitney U tests were used.RESULTS Ameloblastoma was the most common pathology(n=20),followed by CGCG(n=11)and OKC.CGCG showed a higher mean concentration of all quantitative parameters than ameloblastomas(P<0.05).An IC threshold of 31.35×100μg/cm^(3) had the maximum sensitivity(81.8%)and specificity(65%).Between ameloblastomas and OKC,the former showed a higher mean concentration of all quantitative parameters(P<0.001),however when comparing unilocular ameloblastomas with OKCs,the latter showed significantly higher WC.Also,ameloblastoma had a higher IC and lower WC compared to“other jaw tumors”group.CONCLUSION Enhancement characteristics of solid components combined with dual-energy parameters offer a more precise way to differentiate between jaw tumors.

Application of Personalized 3D-Printed Rehabilitation Orthotics in Postoperative Recovery of Jaw Fractures

Objective:To analyze the effectiveness of personalized 3D-printed rehabilitation orthotics in the postoperative recovery of jaw fractures.Methods:Relevant data were collected from 42 patients with jaw fractures treated at our hospital between October 2017 and May 2020.Patients were randomly divided into a traditional group(n=17)and a modified group(n=25).The traditional group received standard rehabilitation methods,while the modified group used personalized 3D-printed rehabilitation orthotics combined with improved rehabilitation methods.The temporomandibular disability index(TDI),quality of life scores,postoperative recovery excellence rate,and mouth opening were compared between the two groups at different follow-up times(before rehabilitation,and at 1 week,3 months,and 6 months post-surgery).Results:At 1 week,3 months,and 6 months post-surgery,the TDI in both the traditional and modified groups was significantly lower than before rehabilitation,with statistically significant differences(P<0.05).At 3 and 6 months post-surgery,the TDI in the modified group was lower than in the traditional group,with statistically significant differences(P<0.05).At 3 and 6 months post-surgery,pain,appearance,activity,recreation,work,chewing,swallowing,speech,shoulder function,and total quality of life scores in both groups were higher than before rehabilitation,with the modified group showing significantly higher scores in pain,appearance,chewing,swallowing,and total quality of life(P<0.05).Compared to before rehabilitation,mouth opening significantly improved in both groups at 3 and 6 months post-surgery,with the modified group showing significantly greater improvement(P<0.05).Conclusion:Personalized 3D-printed rehabilitation orthotics are highly effective in the postoperative recovery of jaw fractures.They can improve patients’quality of life after surgery,enhance the excellent rate of postoperative recovery,and increase mouth opening.

Molecular events in the jaw vascular unit:A traditional review of the mechanisms involved in inflammatory jaw bone diseases

Inflammatory jaw bone diseases are common in stomatology,including periodontitis,peri-implantitis,medication-related osteonecrosis of the jaw,radiation osteomyelitis of the jaw,age-related osteoporosis,and other specific infections.These diseases may lead to tooth loss and maxillofacial deformities,severely affecting patients'quality of life.Over the years,the reconstruction of jaw bone deficiency caused by inflammatory diseases has emerged as a medical and socioeconomic challenge.Therefore,exploring the pathogenesis of inflammatory diseases associated with jaw bones is crucial for improving prognosis and developing new targeted therapies.Accumulating evidence indicates that the integrated bone formation and dysfunction arise from complex interactions among a network of multiple cell types,including osteoblast-associated cells,immune cells,blood vessels,and lymphatic vessels.However,the role of these different cells in the inflammatory process and the'rules'with which they interact are still not fully understood.Although many investigations have focused on specific pathological processes and molecular events in inflammatory jaw diseases,few articles offer a perspective of integration.Here,we review the changes and mechanisms of various cell types in inflammatory jaw diseases,with the hope of providing insights to drive future research in this field.

超声刀Focus刀头及Ligasure Small Jaw~刀头用于开放性甲状腺手术的对照研究

背景与目的：近年来，随着技术发展，越来越多的基于能量传递的止血工具广泛问世并应用于开放性外科手术中。超声刀Focus刀头（Harmonic Focus，HF）及Ligasure Small Jaw刀头（LSJ）都是专为开放性甲状腺手术量身定做的。本文拟对北京协和医学院中国医学科学院肿瘤医院HF及LSJ完成的开放性甲状腺手术患者的临床资料进行病例对照分析，以期比较HF及LSJ在开放性甲状腺手术中的应用效果。探讨HF及LSJ用于开放性甲状腺手术的有效性及安全性。方法：选取本院过去1年内甲状腺癌初治患者，由同一外科医师主刀使用HF或LSJ完成甲状腺全切除＋中央区清扫术，纳入HF组100例，LSJ组104例。通过比较两组手术时间及术后第1天引流量，比较两者在甲状腺手术中应用的有效性。通过比较两组术后并发症来评估安全性。结果：有效性：HF组平均手术时间为（95．8±18．0）min，LSJ组平均手术时间为（97．8±19．1）min，差异无统计学意义（P=-0．363）；术后首日引流量HF组为（35．2±20．3）mL，LSJ组为（36．3±23．8）mL，差异无统计学意义（P=0．977）。安全性：HF组出现暂时性声带麻痹者1例（1．0％），LSJ组术后伤口出现术区血肿者1例（1．0％）；暂时I生甲状旁腺功能低下者HF组18例（18．O％），LSJ组16例（15．4％）；HF组术后首日甲状旁腺素平均下降（12．3±12．8）pg／mL，LSJ组平均下降（13．9±13．4）μg／mL；血清离子钙HF组平均下降（0．20±0．13）mg／dL，LSJ组平均下降（0．20±0．16）mg／dL，差异均无统计学意义（P均〉0．05）。结论：HF及LSJ在开放性甲状腺手术中均安全、有效，手术并发症相当。

Primary tumor prevalence has an impact on the constituent ratio of metastases to the jaw but not on metastatic sites

This article provides an overview of metastases to jaws （M J）, mainly concerning the differences between American and Chinese patients, and exploring the relationship between the primary tumors＇ prevalence （PTP） and constituent ratio of MJ. Information concerning of 399 MJ cases in 215 papers, including one new case in our hospital, was subjected to statistic analysis. The main clinical features of M J, such as constituent ratio of PTP and that of M J, metastatic sites, treatments, and prognosis were summarized. Breast, lung, kidney, prostate and thyroid （in descending order） were the leading primary sites of MJ. Furthermore, the constituent ratio of MJ was found to be correlated with that of PTP in all subjects including American and Chinese subjects in our study. As to metastatic sites in the mandible, a specific ＂M＂ shaped pattern appeared regardless of the tumor type or constituent ratio,,; of MJ were in all subjects. Almost all subjects received traditionary palliative treatments, and the prognosis was quite poor. The PTP had a significant impact on the constituent ratio of MJ. However, it was the properties of the microenvironment rather than characteristics or constituent ratios of tumor cells, that decided the metastatic sites in various tumor subjects.

Influence of some rock strength properties on jaw crusher performance in granite quarry

The influence of rock strength properties on Jaw Crusher performance was carried out to determine the effect of rock strength on crushing time and grain size distribution of the rocks.Investigation was conducted on four different rock samples namely marble,dolomite,limestone and granite which were representatively selected from fragmented lumps in quarries.Unconfined compressive strength and Point load tests were carried out on each rock sample as well as crushing time and size analysis.The results of the strength parameters of each sample were correlated with the crushing time and the grain size distribution of the rock types.The results of the strength tests show that granite has the highest mean value of 101.67 MPa for Unconfined Compressive Strength(UCS) test,6.43 MPa for Point Load test while dolomite has the least mean value of 30.56 MPa for UCS test and 0.95 MPa for Point Load test.According to the International Society for Rock Mechanic(ISRM) standard,the granite rock sample may be classified as having very high strength and dolomite rock sample,low strength.Also,the granite rock has the highest crushing time(21.0 s) and dolomite rock has the least value(5.0 s).Based on the results of the investigation,it was found out that there is a great influence of strength properties on crushing time of rock types.

Symptom distress and interference among cancer patients with osteoradionecrosis of jaw: A cross-sectional study

Objective:Osteoradionecrosis of the jaws(ORNJ)is among the most serious oral complications of head and neck cancer treatment with radiation therapy.This study aimed to examine the level of symptom distress and interference of ORNJ in head and neck cancer patients in China.Methods:A cross-sectional study was conducted to profile patient reported symptom severity.Ninetyfive hospitalized ORNJ patients were recruited.Participants completed the MD Anderson Symptom Inventory-Head and Neck Module-Chinese version.Results:The percentage of participants who reported that they experienced at least one type of symptom was 97.9%,and 85.2%patients reported interference.The 10 most severe symptoms were as follows:limited mouth opening,problem with teeth/gums,difficulty swallowing/chewing,dry mouth,oral malodor,difficulty with voice/speech,dental ulcer,tinnitus/ear obstruction,skin pain/burning/rash,and difficulty hearing.The problem of limited mouth opening was more severe in patients with longer time to onset of ORNJ after radiotherapy.The interference of patients positively correlated with core symptoms(r=0.612),head and neck symptoms(r=0.709),and ORNJ symptoms(r=0.440)(P<0.01).The longer time to the onset of ORNJ after radiotherapy was positively and significantly correlated with symptom distress(r=0.479,P<0.001),and mouth opening correlated negatively with symptom distress(r=-0.298,P=0.003).Conclusions:ORNJ patients suffered mainly from limited mouth opening and other maxillofacial symptoms.The problem of limited mouth opening was more severe in patients with longer time to onset of ORNJ after radiotherapy.ORNJ patients commonly had symptom distress,which influenced their quality of life.

Oral microbiota and host innate immune response in bisphosphonate-related osteonecrosis of the jaw

Bacterial biofilms have emerged as potential critical triggers in the pathogenesis of bisphosphonate（BP）-related osteonecrosis of the jaw（ONJ） or BRONJ. BRONJ lesions have shown to be heavily colonized by oral bacteria, most of these difficult to cultivate and presents many clinical challenges. The purpose of this study was to characterize the bacterial diversity in BRONJ lesions and to determine host immune response. We examined tissue specimens from three cohorts（n530）; patients with periodontal disease without a history of BP therapy（Control, n510）, patients with periodontal disease having history of BP therapy but without ONJ（BP, n55） and patients with BRONJ（BRONJ, n515）. Denaturing gradient gel electrophoresis of polymerase chain reaction（PCR）-amplified 16 S r RNA gene fragments revealed less bacterial diversity in BRONJ than BP and Control cohorts. Sequence analysis detected six phyla with predominant affiliation to Firmicutes in BRONJ（71.6%）, BP（70.3%） and Control（59.1%）. Significant differences（P,0.05） in genera were observed, between Control/BP, Control/BRONJ and BP/BRONJ cohorts. Enzyme-linked immunosorbent assay（ELISA）results indicated that the levels of myeloperoxidase were significantly lower, whereas interleukin-6 and tumor necrosis factor-alpha levels were moderately elevated in BRONJ patients as compared to Controls. PCR array showed significant changes in BRONJ patients with downregulation of host genes, such as nucleotide-binding oligomerization domain containing protein 2, and cathepsin G, the key modulators for antibacterial response and upregulation of secretory leukocyte protease inhibitor, proteinase 3 and conserved helix–loop–helix ubiquitous kinase. The results suggest that colonization of unique bacterial communities coupled with deficient innate immune response is likely to impact the pathogenesis of ONJ.

The value of bone scintigraphy on the determination of the full extent of tumor involvement in jaw bones

Objective： To prospectively investigate the value of bone scintigraphy on determining the full extent of tumor involvement in jaw bones and to assess the presence of metastases. Methods： This study had local ethical committee approval, and all patients gave written informed consent. Thirty seven consecutive patients with primary malignant tumor in jaw bones were recruited for the study. Bone scintigraphy was performed in all patients before surgery to measure the full extent of bony involvement, which was compared with histologic findings. Results： Whole body scan revealed one case with multiple bony metastases. Resection specimens of 36 bone neoplasms were pathologically analyzed to identify type and size of each tumor. The lengths of the tumor involvement in jaw bones defined by bone scintigraphy and pathology were 5.62 ± 1.58 cm, 4.48 ± 1.57 cm, respectively （P 〈 0.05）. The tumor negative margins from removed specimens according to bone scintigraphy were pathologically confirmed. With histologic findings as the standard of reference, the accuracy of bone scintigraphy was 100% （36 of 36 patients） in determining the full extent of tumor involvement in jaw bones. Conclusion： Bone scintigraphy tends to offer specific guidelines in determining the appropriate extent of bone resection while entirely clearing the tumor cells and preserving functions whenever possible and in establishing the bony metastases.

Jaw Osteonecrosis in Patients Receiving Oral Bisphosphonates Therapy

We describe the cases of three patients, under the care of the rheumatology service, who presented with osteonecrosis of the jaw whist on oral bisphosphonate therapy. The first case is of a 74-year-old woman with a 12 year history of sero-negative inflammatory arthritis, having been on oral steroids for 11 years, Methotrexate for the preceding 6 years, and oral bisphosphonates for 9 years. Clinical and radiographic examination revealed extensive jaw necrosis. The second patient was a 72-year-old woman with temporal arteritis, on long term oral steroids, and oral bisphosphonates presenting with jaw osteonecrosis. The third case is of an 81-year-old lady with a diagnosis of Polymyalgia Rheumatica on reducing dose of prednisolone along with calcium and vitamin D3 and oral bisphosphonate therapy as part of steroid induced prophylaxis guidelines. On reviewing the literature regarding bisphosphonate-associated osteonecrosis of the jaw, there is indeed recognition of this occurring with oral bisphosphonates. However, this is far less common than with intravenous preparations. Reports to the UK MHRA regarding adverse reactions have shown 53 cases of osteonecrosis of the jaw associated with oral bisphosphonates, but this is thought to represent under-reporting. We suggest consideration of patient counselling and consent, and preventive dental work prior to initiation of oral bisphosphonate therapy.

Establishment and assessment of rodent models of medication-related osteonecrosis of the jaw(MRONJ)

Medication-related osteonecrosis of the jaw(MRONJ)is primarily associated with administering antiresorptive or antiangiogenic drugs.Despite significant research on MRONJ,its pathogenesis and effective treatments are still not fully understood.Animal models can be used to simulate the pathophysiological features of MRONJ,serving as standardized in vivo experimental platforms to explore the pathogenesis and therapies of MRONJ.Rodent models exhibit excellent effectiveness and high reproducibility in mimicking human MRONJ,but classical methods cannot achieve a complete replica of the pathogenesis of MRONJ.Modified rodent models have been reported with improvements for better mimicking of MRONJ onset in clinic.This review summarizes representative classical and modified rodent models of MRONJ created through various combinations of systemic drug induction and local stimulation and discusses their effectiveness and efficiency.Currently,there is a lack of a unified assessment system for MRONJ models,which hinders a standard definition of MRONJ-like lesions in rodents.Therefore,this review comprehensively summarizes assessment systems based on published peer-review articles,including new approaches in gross observation,histological assessments,radiographic assessments,and serological assessments.This review can serve as a reference for model establishment and evaluation in future preclinical studies on MRONJ.

Efficacy of bone grafts in jaw cystic lesions:A systematic review

BACKGROUND Bone grafts have been applied for many years in orthopedic surgery to assist with bone repair for defects or bone discontinuity caused by trauma and tumors as well as periodontal defects.Jaw cysts are another common benign disease of the maxillofacial region which may lead to pathological bone fracture,loss of teeth,and infection.However,whether bone grafts are beneficial for bone regeneration in jaw cystic lesions and when bone grafts should be used remains unclear.AIM To study the efficacy of bone grafts compared to spontaneous healing in the treatment of jaw cystic lesions.METHODS A literature search was performed in Medline,Cochrane Library and Embase to identify related articles published in English in the last ten years.The following key words and Me SH terms were used:“jaw cyst”,“cystic lesion”,“odontogenic cyst”,“periapical cyst”,“dentigerous cyst”,“follicular cyst”,“keratocyst”,“treatment”,“surgery”,“bone graft”,“enucleation”,“cystectomy”,and“bone regeneration”.Case reports,clinical trials,clinical studies,observational studies and randomized controlled trials were included.Study quality was evaluated.RESULTS Ten studies(n=10)met the inclusion criteria.Five studies reported spontaneous bone healing after enucleation,three studies investigated the efficacy of various bone grafts,and two randomized comparative studies focused on the comparison between spontaneous healing and bone grafting.Over 90%of bone regeneration occurred within 6 mo after bone grafting.The bone regeneration rate after cystectomy showed great variation,ranging from 50%to 100%after 6 mo,but reaching over 90%after 12 mo.CONCLUSION While the long-term superiority of bone grafting compared with spontaneous healing after cystectomy is unclear,bone grafts accelerate the process of healing and significantly increase bone quality.

Enucleation combined with guided bone regeneration in small and medium-sized odontogenic jaw cysts

BACKGROUND The odontogenic jaw cyst is a cavity containing liquid,semifluid or gaseous components,with the development of the disease.In recent years,with the rapid development of oral materials and the transformation of treatment of jaw cysts,more options are available for treatment of postoperative bone defect of jaw cysts.Guided bone regeneration(GBR)places biomaterials in the bone defect,and then uses biofilm to separate the proliferative soft tissue and the slow-growing bone tissue to maintain the space for bone regeneration,which is widely used in the field of implantology.AIM To observe the clinical effect of GBR in repairing bone defect after enucleation of small and medium-sized odontogenic jaw cysts.METHODS From June 2018 to September 2020,13 patients(7 male,6 female)with odontogenic jaw cysts were treated in the Department of Oral Surgery,Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine.Adults without hypertension,heart disease,diabetes or other systemic diseases were selected.The diagnosis was based on the final pathological results:11 cases were diagnosed as apical cysts,one as primordial cyst,and one as dentigerous cyst.The lesions were located in the maxilla in seven cases,and in the mandible in six cases.All cases were treated with the same method of enucleation combined with GBR.RESULTS Three to four months after the operation,the boundary between the implant site and the surrounding normal stroma was not obvious in patients with small-sized odontogenic jaw cysts.The patients with tooth defects were treated with implant after 6 mo.For the patients with medium-sized odontogenic jaw cysts,the density of the center of the implant area was close to the normal mass at 6 mo after surgery,and there was a clear boundary between the periphery of the implant area and the normal mass.The boundary between the periphery of the implant area and the normal mass was blurred at 8-9 mo after surgery.Patients with tooth defects were treated with implants at>6 mo after the operation.CONCLUSION Enucleation combined with guided bone regeneration in small and medium-sized odontogenic jaw cysts can shorten the time of osteogenesis,increase the amount of new bone formation,reduce complications,and improve quality of life.

Material Flow in Jaw Crusher

Jaw crusher is a kind of machine widely used in mining and aggregates industry,but it still has some shortcom- ings,such as liners wear,terrible power draw etc.The lack of research on material flow strongly limits the design improvement. The size reduction of the jaw crusher relies on the moving jaw movement that is a kind of complicated swing.Based on the move- ment analysis of the moving jaw and the single particle breakage characters,the material flow is analyzed.The measure of the breakage force is carried out.Material flow analysis is partly confirmed by the experimental results and some new information is also learned from the crushing force distribution.The job on the material flow will be helpful to the jaw crusher design improve- ment.