A technique for impressing the severely resorbed mandibular edentulous ridge

Patients presenting with severe resorption of the residual alveolar ridges are relatively common today in both private practices and teaching institutions. The severely resorbed mandibular ridge is more challenging to impress than is the maxillary ridge. Accurately capturing the denture-bearing surface in its entirety is crucial to providing the patient with a functionally successful prosthesis. This article presents a technique to overcome the difficulties encountered in impressing the severely resorbed mandibular ridge using elastomeric impression materials and a modified special custom tray.     

舌侧集中[牙合]与三次印模法在全口义齿制作中的临床效果评价

目的:评价制作全口义齿时采用3次印模法配合舌侧集中[牙合]的临床效果。方法:纳入80例低平牙槽嵴患者,随机分为40例实验组(三次印模法)和40例对照组(二次印模法),所有患者均接受舌侧集中[牙合]治疗。在不同时间点,分别对义齿咀嚼效率、患者满意度、义齿基托密合性的指标进行统计分析。结果:实验组在义齿稳定性、咀嚼效率优于对照组(P<0.05),而在美观、发音方面2组间无明显统计学差异(P>0.05)。结论:3次印模法配合舌侧集中[牙合]在修复低平牙槽嵴患者中具有更好的修复效果。     

The prong denture: A combined surgical-prosthetic approach to enhance denture retention

A technique is described where prong extensions were placed on a complete maxillary denture to fit into surgically created skin grafted pockets. Careful selection of patients who will follow oral hygiene instructions meticulously make the prong denture a viable alternative to complete denture construction for the severely resorbed residual alveolar ridge.     

Technique to Fabricate Hollow Maxillary Complete Denture Using 3D Printed Template

Severely resorbed residual alveolar ridges are a challenge in rehabilitation with removable complete dentures. Increased interarch space may result in increased height of maxillary and/or mandibular dentures with corresponding increase in weight, which may compromise retention and resistance of the denture and ultimately, the success of the removable prosthesis. There are many techniques and materials described for reducing the weight of dentures. This article describes an innovative technique for fabricating hollow maxillary dentures using a 3D printed hollow dental surgical guide resin spacer. The double flask technique was used to construct the hollow denture and was modified to incorporate the hollow spacer at the time of final closure of flasks.     

Hollow Maxillary Complete Denture

Residual ridge resorption is the reduction in size of the bony ridge under the mucoperiosteum. The resorption occurs at a faster rate in mandibular arch as compared to the maxillary arch; but severely atrophic maxillae with large interridge distance often pose a clinical challenge during fabrication of a successful maxillary complete denture. This clinical report describes a simple technique of fabricating a hollow maxillary complete denture in a patient with resorbed maxillary and mandibular ridges with increased interridge distance which reduces the weight of the prosthesis and thereby enhances the retention.     

Using tissue conditioner material in neutral zone technique

The looseand unstable lower complete denture is a common problem faced by denture patients. One method used to solve this problem is the neutral zone technique. The neutral zone is the area where the displacing forces of the lips, cheeks and tongue are in balance. In the clinical report presented here, a severely resorbed lower alveolar ridge was treated by determining the neutral zone with tissue conditioner material (Visco-gel, Dentsply Ltd., Weybridge, U.K.). The neutral zone approach with Visco-gel is a more practical and economically feasible treatment for patients having atrophic mandibular ridge.     

Indigenous ball and socket implant supported mandibular overdenture: A case report

Edentulism is a major health concern of old age. Indigenous implant based over dentures offer a cost effective option for severely resorbed dental ridges. Here, we report rehabilitation of a resorbed mandibular arch with indigenous implant supported overdenture and maxillary arch with a conventional denture. Two ball and socket implants were placed bilaterally in the parasymphyseal area. Existing denture was relined to accommodate the ‘ball head’ of the implant in the interim period. Four months later, when patient was taken up for denture fabrication, the ‘socket part’ of the ball and socket implant was incorporated into the new denture base. The socket provided a fitting surface for the implant. Implant supported overdenture significantly increased the retention, support and stability of the lower denture. Further, it worked well with the upper conventional denture. The simple design and efficacy of indigenous implant based overdenture holds promising aspects in the treatment of edentulism.     

改良闭口式印模法在严重吸收下颌无牙患者修复中的应用和效果评价

目的探讨改良闭口式印模法在严重吸收下颌无牙患者修复中的临床应用，并对效果进行评价。方法选取40例严重吸收下颌无牙患者，分为两组，分别采用改良闭口式印模法和传统开口式印模法，进行下颌总义齿修复。修复后1周、2周、1个月和3个月进行随访，评价修复效果。对数据进行统计学分析。结果应用改良闭口式印模法制作的全口义齿，修复后患者在语言、咀嚼、固位及舒适性等方面的满意度与传统开口式印模法有显著性差异，患者的主观满意度明显提高。结论使用改良闭口式印模法制作的全口义齿，更适合功能运动状态下的口腔环境，可以提高功能状态下的固位力。改良闭口式印模法可以作为严重吸收下颌无牙患者修复的常规印模方法。     

Clinical compliance of two resilient denture liners

Although intra-oral-setting resilient denture liners have been used for 30 years to treat the severely resorbed residual ridges of elderly patients, their clinical physical properties are not well understood. The effect of clinical usage on the compliance (compressibility, flexibility) of two intra-oral-setting resilient denture liners was measured in 10 patients, for up to 30 days. The clinical compliance of Material B (Coe-Comfort) was found to be significantly greater than Material A (Veltec) for up to 14 days. At 24 h both materials had significant compliance reductions from the original 1 h measurement. These compliance reductions continued throughout the testing period. For up to 14 days of clinical usage there were no significant differences between the compliance reductions of the two materials. The study suggests that (i) Material B would provide more effective tissue conditioning of abused residual ridge mucosa than Material A; and (ii) a functional impression made with these materials should be left in the mouth for at least 24 h before the cast is poured.     

Complete mandibular denture stability when posterior teeth are placed over a basal tissue incline

Six patients with previous denture experience were provided with new dentures. Metal indicators were placed on either side of the mandibular denture and a cobalt-chromium alloy marker was inserted in the left bucco-posterior area of the mandible in each case. In the new dentures posterior teeth were positioned up to the retro-molar pad, over the basal tissue slope of the posterior mandibular alveolar ridge. After habituation had taken place, a cineradiographic recording was made of chewing. Prior to the second recording the mandibular teeth were removed to a point where the remaining teeth were not over inclined residual alveolar ridges. Denture movement was observed by measuring the distances between the markers on an analytical projector. The results show a significant difference between the cranial values of the two chewing experiences. Values for all denture movements were less after removal of the teeth over an incline. These results support the clinical observation that teeth placed over a basal tissue incline have a destabilising effect during complete mandibular denture function.     

Hydroxyapatite for alveolar ridge augmentation: indications and problems

The increased use of hydroxyapatite for augmentation of residual alveolar ridges has created some problems in the subsequent fabrication of complete denture prostheses. Although hydroxyapatite appears to be an effective substitute for resorbed alveolar ridges, its use is not indicated for all patients. In addition, the premise that "if a little is good, a lot is better" does not apply. The following conclusions can be drawn. Augmentation should not be considered if vestibular extension will provide acceptable results. Placement of hydroxyapatite should improve the contour and amount of the residual alveolar ridge. Use as little as possible to accomplish the goal. Preprosthetic surgery should permit vertical as well as horizontal extension of the denture. Augmentation should not result in the need to use lining mucosa to support a complete denture. Vestibular extensions are indicated for most augmented alveolar ridges. The relative strength of the strong arch should not be increased in prognathic or retrognathic ridge relationships. Preprosthetic surgery should be a combined surgical-prosthodontic treatment endeavor. If a foundation is created that cannot be used effectively for the support, retention, and stability of an intended prosthesis, little benefit is provided for the patient. Small variations in intended treatment can significantly increase success of the prosthesis (Fig. 13). Unfortunately, the relative ease of hydroxyapatite placement has led to its use in patients who do not require augmentation and augmentation in amounts and regions that are not conducive to improving denture success. A coordinated effort between the surgeon and the prosthodontist will usually result in treatment that provides the best potential foundation for a specific patient.     

Ridge splitting technique in atrophic anterior maxilla with immediate implants, bone regeneration and immediate temporisation: a case report

Narrow alveolar ridges remain a serious challenge for the successful placement of endosseous implants. This article reports a technique for widening the atrophic ridge by splitting the alveolar bone longitudinally and filling the bone gap with collagenised pig bone, treatment of ridges as thin as 2.5mm at the alveolar crest and simultaneous placement of dental implants. Treatment of a 22-year-old female patient with a severely resorbed anterior maxilla is described. 4mm wide by 13mm long threaded Osseotite implants were immediately placed within the split ridge and surrounded with a mixture of autogenous tuberosity and collagenised pig bone. The advantages of this technique for patients include less surgical trauma and reduced treatment time.     

Transpositioned flap vestibuloplasty combined with implant surgery in the severely resorbed atrophic edentulous ridge

The use of transpositioned flap (lipswitch) vestibuloplasty combined with implant surgery in patients with severely resorbed atrophic edentulous ridges is reviewed. The cases of 17 patients with severely resorbed atrophic edentulous ridges at the mandible undergoing implant rehabilitation were reviewed. Lipswitch vestibuloplasty was followed immediately by the implant surgery. Postoperative follow-up consisted of clinical and radiographic examinations. Seventeen patients with atrophic ridges (12 class II and 5 class III) each had 2 implant fixtures placed in the mandible as abutments for a clip and bar overdenture. The average time of follow-up was 6 years. Before surgery, all patients had severely atrophic ridges with a compromised shallow vestibule of varying degrees. Satisfactory results were observed in regard to the immediate and long-term morphology of the vestibule, the health of the peri-implant tissue, the stability of implant fixtures, and the functionality of the prostheses. The lipswitch vestibuloplasty offers a safe and convenient method of surgical access for implant fixture installation, with the advantage of rebuilding the vestibule of a compromised atrophic ridge in the anterior mandible.     

具有组织终止带的下颌无牙颌印模技术初探

目的 初步确定并验证一种适用于下颌四类无牙颌的印模技术。方法 对20名四类无牙颌志愿者分别使用常规印模技术和具有组织终止带的印模技术取下颌印模,对比其将松软组织推开的能力以及相应暂基托的舒适度,随机选用其中一个模型完成总义齿制作,检查并记录总义齿初戴时的组织密合度及患者的复诊次数。结果 采用配对t检验显示：两组推开松软组织的能力间差异有统计学意义,舒适度评价差异无统计学意义;采用独立样本t检验显示：两组总义齿组织密合度间差异无统计学意义,复诊次数间差异有统计学意义。结论 具有组织终止带的下颌印模技术可以有效地推开松软组织,虽不能提高初戴的舒适性和基托的组织密合度,但是却有效地减少了患者的复诊次数。     

Anatomic changes of the posterior alveolar ridge and external oblique ridge area in human mandibular edentulous specimens

In this research the posterior alveolar ridge and the external oblique ridge area of 103 mandibular specimens of adult subjects-122 sides with teeth intact and 62 sides with edentulous ridge were measured in different items. The dissection of the external oblique ridge area in 7 cadavers was made and observed. The results showed: (1) the atrophy of residual alveolar ridge of the mandible is severe than that of the maxilla; (2) the resorption of the buccal alveolar plate is more than that of the lingual plate; (3) the resorbed buccal portion of the mandibular alveolar ridge is replaced by the external oblique ridge area, so that the latter becomes wider and flatter. This change of form is beneficial for the denture support and the extension of the buccal flange of the lower denture. The data of the resorption of the buccal alveolar plate provide the reference of the arrangement of the posterior teeth of the lower complete denture. Consequently, we may conclude that the external oblique ridge area is utilizable and beneficial for the support and stability of the lower complete denture.     

改良式印模法促进下颌全口义齿固位的临床探讨

目的:探讨下颌全口义齿改良式印模法的临床应用。方法:5例下颌牙槽嵴低平的无牙颌患者,口角炎反复发作,其旧义齿牙列磨损严重,戴用时稳定性差。本文根据日本学者阿部二郎提出的下颌吸附性义齿理论与临床操作新要求,来介绍改良印模法制作下颌全口义齿的过程。结果:下颌全口义齿可通过改良式印模法实现义齿边缘的完整封闭,增加义齿固位,提高患者咀嚼效率与生活质量。患者评价较满意。结论:改良印模法应用于下颌牙槽嵴低平无牙颌患者,可明显增加义齿固位力。     

全口义齿基托边缘位置及形态的临床研究

目的：分析义齿基托边缘实际位置和形态以及与上下颌解剖标志的关系。方法：按照规范化标准制取功能性印模,为10名无牙颌患者进行全口义齿修复。在义齿试戴前后及义齿使用合适后,测量基托边缘厚度,记录基托边缘调改量,观察基托边缘和上下颌解剖标志的关系。结果：全口义齿基托边缘在翼上颌切迹区、颊棚区、远中颊角区、舌骨嵴区的调改量大,具有统计学意义（P ＜0．05）。下颌义齿颊侧基托边缘在颊棚区与外斜嵴平齐,在远中颊角区避让咬肌附丽。舌侧基托边缘在下颌隆突区与下颌隆突平齐。结论：全口义齿基托边缘在翼上颌切迹区、颊棚区、远中颊角区、及舌骨嵴区易过度伸展。     

改良设计全口义齿修复下颌牙槽嵴低平患者的临床疗效研究

目的：探讨增强下颌严重低平牙槽嵴的老年无牙颌患者全口义齿修复固位、稳定的方法。方法：对在我科就诊的59例患者采用一些特殊的改良型方案进行下颌全口义齿修复用以增强义齿的固位和稳定效果,对比改良型与传统型方法设计、制作的两副下颌全口义齿,并采取问卷的形式获取患者的满意度。结果：经在我科就诊的59例患者对比改良型与传统型方法设计和制作的两副下颌全口义齿使用后,对于改良型方案81.36%（48例）患者作出＂满意＂评价,18.64%（11例）认为＂有改善＂,没有＂无差别＂病例。结论：所采用的特殊改良型措施可有效增强下颌严重低平牙槽嵴全口义齿修复的固位和稳定。     

An examination of the stress distribution in a soft-lined acrylic resin mandibular complete denture by finite element analysis

PURPOSE: The aim of this study was to calculate the effect of a soft liner on stress distribution within a mandibular complete denture. Although patients have welcomed soft-lined complete dentures, early fracture is one of the main reasons for failure. To minimize and prevent prosthesis fracture, the understanding of the stress distribution within a prosthesis is important. MATERIALS AND METHODS: A 3-dimensional finite element model of a mandibular complete denture for a severely reduced residual alveolar ridge was constructed. The stress was calculated with linear static finite element analysis. The stress distribution in the soft-lined acrylic resin mandibular complete denture was compared with that of a conventional acrylic resin denture. The resulting stresses were displayed in terms of von Mises equivalent stress and the major principal stresses according to 5 different loading conditions: vertical loads in premolar, molar, and incisor regions; and oblique loads in premolar and molar regions. RESULTS: Oblique loads produced higher levels of stress in the labial notch regions than vertical loads, where tension was the primary mode of stress. Significantly reduced levels of von Mises stress were calculated in soft-liner layers under all loading conditions. Acrylic resin denture base portions, however, exhibited higher levels of von Mises stress in soft-lined complete dentures. CONCLUSION: Three-dimensional finite element analysis gave a realistic explanation of denture fractures and patient response to mandibular complete dentures with and without soft linings. Control of excess lateral occlusal contact might be helpful to reduce the probability of a fracture in soft-lined mandibular complete dentures.     

A Simplified Approach for Recording Neutral Zone

Neutral zone technique is long being used for the management of severely resorbed mandibular ridges. Various materials are used in recording neutral zone, which have their own advantages and disadvantages. This article discusses the use of Polyether impression material which is simpler and more practical.