下颌起排法全口排牙临床效果研究

目的:研究通过比较不同的排牙方式制作的全口义齿对咀嚼次数、咀嚼效率以及患者的主观感受的影响。方法:78例无牙颌患者按照牙槽嵴高度分为正常组和低平组,正常组有患者32例,低平组有患者46例,每组分别戴用上颌起排法和下颌起排法制作的全口义齿,比较咀嚼次数、咀嚼效率和满意度的差别。结果:在戴用上颌起排法制作的全口义齿时,正常组的咀嚼次数高于低平组,差异具有统计学意义(t=3.60,P0.05);戴用下颌起排法制作的全口义齿后,低平组的咀嚼次数高于采用上颌起排法的全口义齿,差异具有统计学意义(t=4.41,P0.05);在戴用上颌起排法制作的全口义齿中,正常组的咀嚼效率高于低平组,差异具有统计学意义(t=5.72,P0.05);而在戴用下颌起排法制作的全口义齿后,低平组的咀嚼效率高于采用上颌起排法的全口义齿,差异具有统计学意义(t=7.16,P0.05)。正常组认为使用下颌起排法制作全口义齿咀嚼能力、稳固感好于上颌起排法,差异均具有统计学意义(P0.05);低平组认为使用下颌起排法制作全口义齿咀嚼能力、稳固感和舒适感好于上颌起排法,差异均具有统计学意义(P0.05)。结论:对于牙槽嵴低平无牙颌患者使用下颌起排法制作的全口义齿,能够有效地增强咀嚼效率,提高义齿的稳定性。     

Residual ridge atrophy in complete denture wearers and relationship with densitometric values of a cervical spine: a hierarchical regression analysis

doi: 10.1111/j.1741‐2358.2011.00589.x Residual ridge atrophy in complete denture wearers and relationship with densitometric values of a cervical spine: a hierarchical regression analysis Background: The rate of residual ridge atrophy (RRR) and its association with mineral density of other bones have not yet been fully explained. Objective: To measure RRR over a 5‐year period in complete denture wearers and relate it to the density of a cervical spine (CSBD). Materials and methods: Sixty‐two patients (different gender, age, body mass index, duration of edentulousness (DE) and different denture‐wearing habits) participated. A copper stepwedge was attached to the cassette, and 50 lateral radiograms met the criteria to be included. Results: A significant decrease in vertical height was observed in all measured sites. The amount of RRR was highest in frontal areas of both jaws and decreased gradually towards lateral regions. Hierarchical regression analysis revealed that the amount of RRR in the maxillary frontal area could be explained up to 48.4% by the variable DE and only up to 6.1% by the CSBD, while gender had almost no influence (1%). Similar results were obtained for the lateral maxillary RRR (33.9%; 7%; 2%), frontal mandibular RRR (40; 8.4; 0.4%) and lateral mandibular RRR (31.5%; 3.4%; 7.7%). Conclusion: Skeletal bone density, reflecting systemic and hereditary factors, is weakly related to RRR (3.4–8.4%).     

The effect of osteoporosis on residual ridge resorption and masticatory performance in denture wearers

doi: 10.1111/j.1741‐2358.2011.00610.x The effect of osteoporosis on residual ridge resorption and masticatory performance in denture wearers Aim: To compare masticatory performance, masticatory efficiency and residual ridge resorption (RRR) in osteoporotic and non‐osteoporotic edentulous subjects after rehabilitation with complete dentures. Method: Thirty subjects fulfilling the inclusion criteria were enrolled from the patients visiting the Department of Prosthodontics for complete denture fabrication. Two groups consisting of control subjects (group I; N = 15) and osteoporotic subjects (group II; N = 15) were formed. Complete dentures satisfying certain criteria were fabricated for both groups. Masticatory performance and efficiency were measured 6 months after denture insertion. Areal measurements were taken on lateral cephalograms before and 6 months after denture fabrication. The data were then computed to analyse differences between groups I and II using SPSS statistical software version 15.0. Results: Six months after denture fabrication, the masticatory performance and efficiency were significantly higher (p < 0.001) for group I, with a significant decrease in maxillary and mandibular sagittal area seen in both groups. The rate of bone loss was more in group II compared with group I. Conclusion: Greater masticatory function was demonstrated by the non‐osteoporotic group, and the rate of RRR was more in the osteoporotic group compared with the normal group. In this pilot study, osteoporosis leads to greater RRR, decreased masticatory performance and efficiency in edentulous subjects 6 months after denture insertion. Screening for osteoporosis is suggested as a routine procedure for all edentulous subjects undergoing rehabilitation. Recall check‐ups for osteoporotic patients should be more frequent, and these patients may require more frequent denture remakes.     

Impact of Human Genome Project on treatment of frail and edentulous patients

Objective: Because of ongoing increases in life expectancy and deferment of edentulousness to older age, dentists are facing a different challenge to satisfy elderly denture wearers with a higher prevalence of chronic diseases. This discussion introduces the Human Genome databases as novel and powerful resources to re‐examine the core problems experienced by frail and edentulous patients. Background: Recent studies demonstrated that mandibular implant overdentures do not necessarily increase masticatory function, perception and satisfaction in denture wearers with adequate edentulous residual ridges. It has been demonstrated that the rate of edentulous residual ridge resorption significantly varies among individuals. The prognosis and cost‐effectiveness of denture treatment, with or without implants, may largely depend on how the edentulous ridge is maintained. However, reliable clinical methods permitting dentists to predict the long‐term health of the edentulous residual ridge are lacking. Materials and methods: With the completion of the Human Genome Project, the genomic sequence database from this multinational consortium will provide a unique resource to determine the genetic basis of similarity and diversity of humans. Results: One base pair in every 100 to 300 base pairs of the genome sequence varies among humans, suggesting that genetic diagnosis using the single nucleotide polymorphisms (SNPs) may provide a novel opportunity to differentiate our edentulous patients. Conclusions: Future dental service for the elderly will require a personalized care paradigm, using highly sensitive diagnostic technology such as SNP genomic analysis, for recommending the treatment with greatest potential benefit.     

Radiographic evaluation of alveolar ridge heights of dentate and edentulous patients

doi: 10.1111/j.1741‐2358.2010.00391.x Radiographic evaluation of alveolar ridge heights of dentate and edentulous patients Objective: To evaluate the reduction of residual alveolar ridge height on panoramic radiographs and the differences between denture wearers and non‐denture wearers. Materials and methods: The study consisted of 147 individuals (74 men and 73 women) [50 were denture wearers and 50 non‐denture wearers (examination groups) and 47 of them were dentate (control group)]. Individuals having diseases impacting on bone were excluded. Vertical measurements were made at 15 sites (central incisors, first premolars and molars at the left and right of both jaws and the distance between the zygoma/orbit). MANOVA (multi‐variate analysis of variation) was used for the statistical analysis of the results. Results: There were significant differences between the alveolar ridge heights of dentate and edentulous groups (p < 0.001). Between the denture wearer and the non‐denture wearer groups, there was significant difference in the lower jaw (p < 0.001), but no significant difference in the upper jaw (p = 0.635). There were also differences between men and women (p < 0.005) and upper and lower jaws at every measurement sites (p < 0.01). Conclusion: Reduction in residual alveolar ridge height was in close relation with gender, denture usage and edentulousness.     

Two-dimensional finite element analysis of stresses developed in the supporting tissues under complete dentures using teeth with different cusp angulations

Statement of problem: The selection of appropriate teeth for complete denture occlusion is very important for long‐term success, and adequate maintenance of the residual alveolar ridge. Purpose: The purpose of this study was to determine the stress generated underneath the complete denture by altering the cuspal angulations of the denture teeth. Material and methods: A two‐dimensional finite element model of a coronal section of maxillary and mandibular complete dentures, mucosa and alveolar bone in the first molar region was designed. The occlusal aspect of the denture teeth was altered to make 33°, 20°, 0° cuspal angulation. All the nodes at the bases of maxillary and mandibular alveolar bone of finite element analysis models were restrained in all directions. A functional occlusal load of 50 N was applied through the mandibular model base. To design these models and to analyse them, EMRC’s NISA II finite element analysis computer software was used. In these models, the elements were selected (a, b, c, d, e, f) in the region where it was necessary to determine the stresses generated in both the maxillary and mandibular portions. Results: The results were interpreted as Von Mises stresses and were observed in pre‐defined areas. The stress patterns observed within model with each type of posterior occlusion, showed unique variations as well as some similarities. Conclusion: Stresses of greater magnitude were observed in cuspal teeth, 33° and 20° respectively, where as 0° teeth showed a slightly less magnitude of stress generated.     

Prevention of trauma to edentulous ridge from opposing natural teeth

doi: 10.1111/j.1741‐2358.2010.00397.x Prevention of trauma to edentulous ridge from opposing natural teeth Objective: To suggest a technique to prevent trauma of the edentulous ridge from opposing natural or restored teeth. Background: The prevalence of the condition where one edentulous arch opposes a natural or restored dentition is quite common. In most of cases, the maxillary arch is completely edentulous and either all teeth or only anterior teeth are present in the mandibular arch. These remaining teeth may continuously cause trauma to the opposing edentulous ridge during the night when a removable prosthesis is kept out of the mouth. Materials and methods: A thermoplastic acrylic resin mouthguard was fabricated on a cast of the remaining teeth dentition. Conclusion: This article presents a simple and inexpensive procedure to prevent self‐induced trauma of the edentulous ridge from opposing natural teeth by using a thermoplastic acrylic resin mouthguard.     

下颌种植覆盖义齿的生物力学研究进展

口腔生物力学是用生物力学的概念和方法,研究口腔医学中的有关基础性科学问题、解决口腔医学中的临床实际问题、发展口腔临床技术的一门学科。在口腔正畸学、修复学、种植学及口腔颌面外科学等领域存在着大量的生物力学问题,生物力学已成为口腔医学的基础科学之一。传统全口义齿修复常常会出现固位稳定差、咀嚼效率低、患者有疼痛感、适应时间长等情况,很大程度上不能满足患者的修复要求。种植覆盖义齿对于下颌牙槽嵴严重吸收的患者,效果尤为明显。种植覆盖义齿是义齿与种植体之间以不同的附着体作为连接,形成患者可以自行摘戴的种植体支持的覆盖义齿修复。下颌种植覆盖义齿因其能有效地提高下半口义齿的固位性和稳定性、显著提高了患者的咀嚼效率,目前已成为修复下颌牙槽骨严重吸收的无牙颌患者的有效修复方法。本文针对下颌种植覆盖义齿的生物力学研究进展作一综述。     

Survival analysis of mandibular complete dentures with acrylic‐based resilient liners

doi: 10.1111/j.1741‐2358.2012.00658.x Survival analysis of mandibular complete dentures with acrylic‐based resilient liners Objective: The purpose of this long‐term randomised controlled trial was to compare the longevity of dentures constructed using a conventional acrylic resin (CAR) to that of dentures constructed using an acrylic‐based resilient liner (ARL). Materials and methods: The follow‐up study was essentially carried out by annual telephone calls to each of the 67 participants. The Kaplan–Meier method and life‐table analysis were used for univariate analyses. The Cox proportional‐hazards test was used as a final model for statistically adjusting predictor variables such as sex, clinician type, mandibular denture type and age at denture delivery. Results: The denture type was likely to affect the survival time of the dentures, while the sex and clinician type were not. The group using acrylic‐based resilient denture liners had twice the risk of having shorter denture‐survival times than those using conventional acrylic resin dentures. Younger participants were likely to have a reduced risk of having shorter denture‐survival times than older participants. Conclusion: We conclude that mandibular complete dentures constructed using ARL are twice as likely as dentures constructed using CAR to have shorter denture survival times, mainly because of material deterioration.     

钛镍记忆合金牵张器复合脱细胞真皮基质增高犬牙槽嵴的初步研究

目的用成年杂种犬建立钛镍记忆合金牵张器复合脱细胞真皮基质增高犬牙槽嵴动物模型,为下一步利用钛镍记忆合金牵张器行下颌后牙牙槽嵴增高术奠定基础。方法健康成年雄性杂种犬4只。全麻下拔除双侧下颌4个前磨牙和第一磨牙,1个月后拍摄双侧后牙区X线光片,观察拔牙窝愈合情况。采用4种类型的牵张器随机在4只犬的下颌两侧行牵张手术并观察牵张后1周和1月牙槽嵴增高的情况。结果拔牙后1个月,牙槽嵴黏膜愈合良好。X线片示下颌神经管清晰可见,其上方牙槽窝内有较低密度骨质存在。放置4种牵张器牵张术后1周、1月后牙槽嵴增高的高度分别为3.24 mm、3.76 mm、4.58 mm、5.09 mm;3.15 mm、3.67 mm、4.64 mm、5.01mm,术后一周X线可见后有明显的牵张间隙,1月时牵张区有新骨形成,骨密度增高。结论犬耐受力强,后牙区下颌骨体积大,手术易操作,是理想的牙槽嵴萎缩动物模型。拔牙后1个月,拔牙创愈合良好,可以进行牵张手术。D组＂S＂形牵张器牵张后的高度比较理想,能满足后期种植体的植入。     

Mechanical response comparison in an implant overdenture retained by ball attachments on conventional regular and mini dental implants: a finite element analysis

This study investigates the bone/implant mechanical responses in an implant overdenture retained by ball attachments on two conventional regular dental implants (RDI) and four mini dental implants (MDI) using finite element (FE) analysis. Two FE models of overdentures retained by RDIs and MDIs for a mandibular edentulous patient with validation within 6% variation errors were constructed by integrating CT images and CAD system. Bone grafting resulted in 2 mm thickness at the buccal side constructed for the RDIs-supported model to mimic the bone augmentation condition for the atrophic alveolar ridge. Nonlinear hyperelastic material and frictional contact element were used to simulate characteristic of the ball attachment-retained overdentures. The results showed that a denture supported by MDIs presented higher surrounding bone strains than those supported by RDIs under different load conditions. Maximum bone micro strains were up to 6437/2987 and 13323/5856 for MDIs/RDIs under single centric and lateral contacts, respectively. Corresponding values were 4429/2579 and 9557/5774 under multi- centric and lateral contacts, respectively. Bone micro strains increased 2.06 and 1.96-folds under single contact, 2.16 and 2.24-folds under multiple contacts for MDIs and RDIs when lateral to axial loads were compared. The maximum RDIs and MDIs implant stresses in all simulated cases were found by far lower than their yield strength. Overdentures retained using ball attachments on MDIs in poor edentulous bone structure increase the surrounding bone strain over the critical value, thereby damaging the bone when compared to the RDIs. Eliminating the occlusal single contact and oblique load of an implant-retained overdenture reduces the risk for failure.     

Implant‐supported overdenture in an elderly patient with Huntington’s disease

doi:10.1111/j.1741‐2358.2009.00343.x
Implant‐supported overdenture in an elderly patient with Huntington’s disease Huntington’s disease is a hereditary, progressive, neuro‐degenerative disorder characterised by increasingly severe motor impairment, cognitive decline and behavioural manifestations leading to functional disability. Dyskinesia and hyperkinesia of the tongue and the peri‐oral musculature make it impossible for the patient to wear a conventional complete denture, despite an adequate alveolar ridge. The present paper reports on a patient with Huntington’s disease who was rehabilitated with a mandibular overdenture supported by two endosteal implants. One year follow‐up examination showed that the prosthesis was stable and there was considerable improvement in the patient’s masticatory function.     

Decreasing of residual alveolar ridge height in complete denture wearers. A five year follow up study

The resorption of the residual alveolar ridges is a chronic and continuous process of bone remodeling. The aim of this study was to analyse the rate of residual ridge resorption at different sites in the both jaws in complete denture wearers, through a five-year period of denture wearing. Residual ridge changes were measured on successive lateral cephalograms at 5 measurement points of the maxilla and the mandible. The first lateral radiograph was obtained at the delivery of complete dentures. The second lateral cephalogram was obtained after five years of denture wearing. Measurements were performed using a calibrated grid. The results of this study showed the existence of a significant alveolar ridge resorption at all five measurement points of the maxilla and the mandible. The observed variables, such as body mass index and the night time denture wearing had no significant influence on the rate of residual alveolar ridge resorption (p > 0.05). The duration of edentulousness had a significant influence on the rate of residual ridge resorption with significantly higher amounts of alveolar bone height decrease in those patients who had lost the last remaining teeth more recently.     

应用电子散斑干涉术对单端固定桥的受载分析

本文目的是对单端固定桥的运动及其受力状态进行试验性研究。采用电子散斑干涉术这一新的光学技术分别对下颌单端固定桥修复前后进行４种垂直加载测试,观察实时显示的散斑干涉条纹图,并测量相应牙槽骨处的离面位移。     

全口义齿修复后造成松软牙槽嵴和／或牙槽嵴粘膜增生的原因初探

目的:研究松软牙槽嵴和/或牙槽嵴粘膜增生形成的原因,探讨预防和治疗措施。方法:对180例戴用全口义齿一年以上的患者进行临床调查研究。研究内容包括缺牙原因,义齿戴用的时间,牙槽嵴粘膜情况,松软牙槽嵴和/或牙槽嵴粘膜增生发生的部位,人工牙的类型等。结果:①180例全口义齿病例中,有松软牙槽嵴者20例,占22％,男:女=6:4,其中下牙槽嵴占60％,上牙槽嵴占,20％,上下牙槽嵴均有者占20％。患牙槽嵴粘膜增生者共8例,占4.4％,最多发生在下舌侧,其次为下唇沟。同时患有松软牙槽嵴和牙槽嵴粘膜增生的有4例,占患牙槽嵴粘膜增生病例的一半。②在患松软牙槽嵴的病例中,人工牙为塑料牙和瓷牙各占50％。缺牙原因为牙周病者共12例,占60％,龋病2例,占10％,龋病-牙周病者8例,占30％。③在患松软牙槽嵴的病例中,下颌牙槽嵴条件均为差,上颌牙槽嵴条件均为中或差。在患增生的粘膜组织的病例中,75％病例义齿固位为中或差,25％义齿固位为较好。结论:发病原因与患者缺牙原因,牙槽嵴部位,牙槽嵴条件,人工牙类型等有关。因此可以认为,牙槽嵴粘膜松软是戴用全口义齿后出现的不可忽视的问题,而牙槽嵴粘膜松软和/或增生的粘膜组织是相辅相成的。所以一副全口义齿不是一劳永逸的,使用一定的时间后需要更换,特别对牙槽嵴条件较差的患者     

Correlation between residual ridge resorption and radiomorphometric indices

doi: 10.1111/j.1741‐2358.2011.00514.x Correlation between residual ridge resorption and radiomorphometric indices Objectives: The study evaluated the relationship between residual ridge resorption (RRR) and radiomorphometric indices, including mandibular cortical index (MCI), mandibular cortical width (MCW) and panoramic mandibular index (PMI), along with demographic factors. Material and methods: Panoramic radiographs of 1863 patients over 20 years of age were assessed. Gender, age and dental status of each patient were recorded. Relationships between RRR and demographic factors and radiomorphometric indices were evaluated using chi‐square and Fisher’s exact tests with level of significance of p = 0.05. Results: Residual ridge resorption was not affected by gender (p > 0.05), but was more frequently seen in patients over the age of 50 compared with those below 49 years of age (p < 0.001). RRR was significantly associated with edentulism (p < 0.001) and with severe erosions of endosteal margin of mandible (p < 0.05). RRR was more frequently seen in patients with PMI below 0.30 (p < 0.001) and with MCW below 3 mm in 50‐ to 69‐year‐old age group (p < 0.001). Conclusions: Patients younger than 50 years of age who demonstrate severe erosions of endosteal margin of mandible and have MCW < 3 mm and PMI < 0.30 appear to be suitable candidates for early implant placement or for maintaining roots or natural teeth to preserve bone, regardless of gender.     

The influence of mandibular implant-retained overdentures in masticatory efficiency

doi: 10.1111/j.1741‐2358.2011.00539.x The influence of mandibular implant‐retained overdentures in masticatory efficiency Objective: To evaluate the masticatory efficiency of patients rehabilitated with conventional dentures (CDs) or implant‐retained mandibular overdentures. Background: Despite the evident benefits of implants on mastication as assessed by subjective patient‐based outcomes, the extent of implant overdenture treatment effect on food comminution is not well established. Materials and methods: A randomised clinical trial was carried out with 29 completely edentulous patients divided into two groups. The first group was rehabilitated with a mandibular overdenture retained by two splinted implants with bar‐clip system, while the second group was rehabilitated with a mandibular CD. Both groups also were rehabilitated with maxillary CDs. Masticatory efficiency and patient satisfaction were assessed 3 months after denture insertion. Masticatory efficiency was evaluated through the colorimetric method with the beads as the artificial test‐food. Comparisons for masticatory efficiency and patient satisfaction were performed using Student’s t‐test (α = 0.05). Results: No significant statistical difference was found for masticatory efficiency (p = 0.198). Patient overall satisfaction was significantly higher for the mandibular overdenture (p < 0.001). In addition, mandibular overdenture patients were significantly more satisfied with chewing experience (p < 0.05) and retention of the lower denture (p < 0.005). Conclusion: The results of this study suggest that mandibular overdenture significantly improves chewing experience, although limited effect on masticatory efficiency has been observed.     

The Effect of Non-Contact Conditions in a Splinted Fixed Partial Denture on the Load Sharing Mechanism: A Finite Element Study

A computer-aided design model for a fixed partial denture was constructed and used in a finite element analysis to study the overall load sharing mechanism between the fixed partial denture and oral structures while the denture base rested on the alveolar ridge.To investigate the consequences of non-contact conditions,three additional models were generated incorporating a uniform clearance of 0.125 mm,0.25 mm,and 0.5 mm,respectively.A 100 N static load located at the free end of the prosthesis was applied while the distal portion of the jaw was set fixed.The results show that whilst releasing the ridge almost entirely,the presence of the clearance drastically increased the load on the splinting teeth.A pull-out force on the canine tooth of about 44 N was computed,accompanied by a mesio-distal moment of about 500 N.cm.The combination of which was similar to the tooth extraction maneuver performed by the dentist.In contrast,the second premolar was found to bear a push-in force of almost 115N.The first molar,though barely solicited in the contact condition,became substantially loaded in non-contact conditions,which validates the choice of sacrificing three teeth to support the denture.     

Accelerated rehabilitation of an edentulous patient with an implant retained dental prosthesis: a case report

This case report details the successful rehabilitation of an edentulous patient using a complete upper prosthesis and a lower implant retained overdenture. The provision of care was split between a specialist centre and a primary care setting. This approach reduced inconvenience to the patient. Modern surgical and prosthodontic techniques also reduced the total delivery time. After initial consultation a new set of complete dentures was prescribed with changes in design to the originals. The patient was also planned for placement of two mandibular implants to stabilise and retain the mandibular denture. The first line of treatment involved provision of a new set of dentures constructed by the patient's general dental practitioner. Dental implants were then placed in a specialist centre and the patient returned to the dental practice for attachment of the lower denture to the dental implants. The benefits and success of mandibular implant retained dentures are well documented. With delivery of the overdenture, the patient reported increased satisfaction with his prostheses which allowed him to eat a greater range of foods and enabled him to feel confident when speaking and socialising.