A Simplified Guide for Arranging 30° Pilkington Turner Posterior Denture Teeth in a Balanced Occlusion

A simple technique is presented for achieving balanced occlusion when setting 30 degrees Pilkington-Turner teeth. This technique involves the rotation of the mandibular posterior teeth around three axes: the vertical axis, to align the grooves and embrasures with the lateral path of the movement of the cusps; the mesio-distal axis, to achieve the Curve of Wilson; and the bucco-lingual axis, resulting in the Curve of Spee.     

The Development of Nonanatomic Denture Occlusion: Part III

Part III of this four‐part series about nonanatomic denture tooth development traces the evolution of this movement from the mid‐1930s through the World War II era up to the early 1950s. By this time, the general preference for posterior denture occlusion had shifted from anatomic to nonanatomic teeth, and all the major denture tooth manufacturing companies listed at least one nonanatomic design in their inventories.     

铸造牙间卡用于可摘局部义齿修复

目的:改善铸造可摘局部义齿固位体的美观性,减轻颊侧固位体的异物感。方法:在两基牙间的颊、龈外展隙内设置牙间卡(发夹卡)。结果:固位体金属外露少、隐蔽性好,美观明显改善,同时,体积小,无异物感。对34例不同牙缺失患者的使用,经1~2年观察,修复体固位良好,基牙未见松动和移位。结论:铸造牙间卡在美观、制作和异物感等方面明显优于常规铸造冠外固位体。     

Nasal Width as a Guide for the Selection of Maxillary Complete Denture Anterior Teeth in Four Racial Groups

PURPOSE: Selecting artificial teeth for edentulous patients is difficult when pre-extraction records are not available. Various guidelines have been suggested for determining the width of the maxillary anterior denture teeth. This study was undertaken to evaluate the use of the nasal width as a guide for the selection of proper width maxillary anterior denture teeth in four racial groups of the Brazilian population. MATERIALS AND METHODS: One hundred and sixty subjects (40 Whites, 40 Mulattos, 40 Blacks, and 40 Asians) were selected. Using a sliding caliper, the nasal width and the intercanine distance were measured. The Pearson product-moment correlation coefficient was used to determine the relationship between the above measurements. A prediction was made of the percentage of subjects of the White, Mulatto, Black, and Asian populations in which the selection error due to the clinical application of the method of the nasal width would be within 0 to 2 mm, within 2 to 4 mm, and greater than 4 mm. RESULTS: The four racial groups showed a weak correlation between the intercanine distance and the nasal width. In 39.7% of the White, 55.7% of the Mulatto, 81.9% of the Black, and 48.2% of the Asian populations, errors greater than 4 mm would be present with the use of the nasal width. CONCLUSIONS: The correlation found between the intercanine distance and the nasal width was not high enough to be used as a predictive factor. The relationship between natural tooth width and artificial tooth width as predicted by the nasal width showed that the nasal width method is not accurate for all the studied groups.     

In Vitro Wear of Nano-Composite Denture Teeth

PURPOSE: Few laboratory tests have been able to substantiate and quantify the wear resistances of polymeric denture teeth. This study evaluated the relative wear resistance of several types of denture teeth using an in vitro wear testing device. MATERIAL AND METHODS: Four different types of denture teeth [nano-filled (Veracia) and micro-filled composites (SR-Orthosit, Endura, Duradent, Surpass), cross-linked acrylic (SR-Postaris, Genios-P, Creapearl, Vitapan Physiodens, Premium 8, Integral), and a conventional acrylic (Biotone)] were used. The flattened buccal surface of each denture tooth was subjected to the evaluation of Knoop hardness (n=5) and localized wear for 100,000 cycles (n=10). Wear values were determined in micrometers using a profilometer. The data for the hardness, wear depth, and worn surface areas were individually analyzed by one-way ANOVA. RESULTS: Knoop hardness values (KHN) ranged from 28.2 to 29.8 for micro-filled composite, 18.9 to 21.6 for cross-linked acrylic, 22.7 for nano-composite, and 18.6 for conventional acrylic teeth. All micro-filled composite teeth were significantly harder than other teeth (p <0.0001). The wear depth values were 90.5 microm for the nano-composite, 69.8 to 93.0 microm for the micro-filled composite, 80.8 to 104.0 microm for the cross-linked acrylic, and 162.5 microm for conventional acrylic teeth. The worn surface areas were 5.1 mm2 for the nano-composite, 2.6 to 3.6 mm2 for the micro-filled composite, 4.4 to 5.7 mm2 for the cross-linked acrylic, and 10.1 mm2 for conventional acrylic teeth. The wear values of the acrylic control were significantly different from all other denture teeth (p <0.001). CONCLUSION: The nano-composite tooth was harder and more wear resistant than the acrylic teeth but not significantly different from most of the cross-linked and micro-filled composite teeth tested.     

The Development of Nonanatomic Denture Occlusion: Part IV

This fourth and final part of a four‐part series concerned with the development of nonanatomic denture occlusion follows nonanatomic tooth design from the time of Victor Sears’ first nonanatomic tooth patent through the end of the 20th century. Part IV concentrates on nonanatomic teeth developed during the last five decades of the 20th century. Many of the designs featured in this series exhibited genius, while others are pure nonsense. Sears claimed that a new nonanatomic tooth design appeared every 9 months on average during the first 30 years of nonanatomic tooth production. Many current nonanatomic tooth patents are further refinements of those earlier designs.     

The Development of Nonanatomic Denture Occlusion: Part II

This second part of a four‐part series concerned with the development of nonanatomic denture occlusion follows nonanatomic tooth design from the time of Victor Sears’ first nonanatomic tooth patent through the mid‐1930s. Many of the designs featured in this series exhibit genius, while others are pure nonsense. Sears claimed that a new nonanatomic tooth design appeared every 9 months on average during the first 30 years of nonanatomic tooth production. Many current nonanatomic tooth patents are further refinements of those earlier designs. Part II reviews pioneering designs that appeared during the first dozen or so years of this paradigm shift in denture occlusion philosophy.     

Failure Modes with Point Loading of Three Commercially Available Denture Teeth

Purpose: A common problem associated with implant-supported prostheses is the fracture of denture teeth. This study was designed to compare the fracture modes of three denture teeth by compressive load at a 30° off-axis angle.
Material and Methods: Three denture teeth (Vident Duostat, Ivoclar Vivadent, and Dentsply Trubyte) processed to two denture base processing systems [injection-molded (IM) SR-Ivocap system and compression-molded (CM) denture base resin] were evaluated. Each specimen was processed to a metal framework. Ultimate failure strength of each system when point loaded at a 30° off-axis angle was recorded, along with a visual inspection of each specimen.
Results: The average load fracture for each group was (in N): Vident CM 1106.97 ± 223.20, Vident IM 1168.18 ± 322.52, Dentsply CM 1098.08 ± 286.32, Dentsply IM 1023.80 ± 282.45, Ivoclar CM 1616.98 ± 204.87, and Ivoclar IM 1373.54 ± 282.58. There was a significant difference between the groups and the Ivoclar CM group. The Ivoclar CM group had the highest average load force, and the Dentsply IM group had the lowest average load force. On average, the teeth within the groups fractured at a higher compression force than the average maximum occlusal force in natural dentition. Dentsply and Vident denture teeth fractured more horizontally, and the Ivoclar denture teeth fractured more vertically within the groups. There was no significant difference among the groups between the IM and CM processing methods.
Conclusions: In the present in vitro study, all specimens were able to withstand 30° off-axis loading with the exception of one specimen. With these results, this would indicate that these denture teeth are able to withstand normal occlusal forces.     

Restoration of the Occlusal Vertical Dimension with an Overlay Removable Partial Denture: A Clinical Report

The process of tooth loss throughout life associated with severe occlusal wear may pose a challenge in the rehabilitation of partially edentulous arches. In these cases, many therapeutic procedures are necessary because each tooth must be restored to obtain the correct anatomical contour and recover the occlusal vertical dimension (OVD). A removable partial denture (RPD) with occlusal/incisal coverage, also known as an overlay RPD, is an alternative treatment option with fewer interventions, and, consequently, lower cost. This clinical report reviews the principles involved in the clinical indication for an overlay RPD, as well as the necessary planning and execution, to discuss the feasibility and clinical effectiveness of this treatment, identifying the indications, advantages, and disadvantages of this procedure through the presentation of a clinical case. The overlay RPD can be an alternative treatment for special situations involving partially edentulous arches in patients who need reestablishment of the OVD and/or realignment of the occlusal plane, and it can be used as a temporary or definitive treatment. The main advantages of this type of treatment are its simplicity, reversibility, and relatively low cost; however, further studies are needed to ensure the efficacy of this treatment option.     

A Technique to Correct Anterior‐Posterior Tooth Discrepancy for a Maxillary Immediate Complete Denture

This article describes a chairside technique to correct inappropriate occlusal vertical dimension as well as the inaccurate anterior‐posterior tooth set‐up of a maxillary immediate complete denture. When fabricating an immediate denture, the inability of a wax‐denture trial and the potential for unpredictable complications during surgery, compromised esthetics and function of an immediate complete denture may pose a clinical problem, which needs instant correction. The technique described can provide an alternative method to correct and deliver a definitive immediate complete denture on the day of surgery.     

人工牙排列位置对下颌全口义齿固位及支持组织的影响

采用ＣＴ－数字化仪－ＣＡＤ系统建立了下颌无牙颌骨及其义齿的３个三维有限元模型，探讨在Ｈｅ力，口周肌力作用下，下颌人工牙排列位置对义齿固位和支持组织应力分布的影响，并测量了１０例口周肌动力及传统型全口义 工牙排列位置的差异。结果表明；Ｈｅ力作用下，人工牙排列干剩余牙槽嵴顶及水平偏离槽嵴顶舌，颊侧３ｍｍ，对牙骨应力分布无明显影响，但后牙位于下颌骨外斜嵴区对支持组织有利；正中Ｈｅ时，磨牙排列于牙槽嵴顶颊     

The Development of Nonanatomic Denture Occlusion – Part I

Part I of this two‐part article concentrates on the early 20th century origin of the nonanatomic concept of complete denture occlusion. It focuses on Dr. Victor Sears, who in 1922 made a courageous departure from convention when he introduced the design for his “Chewing Members.” Development of these teeth marked the birth of the School of Nonanatomic Denture Occlusion. Dr. Sears’ 35‐year journey of research and development is traced here through his mid‐1950s association with Dr. Simon Myerson. Their Myerson‐Sears design set the standard for flat‐planed, nonanatomic denture teeth for the next half century.     

Comparison of Stress Dissipation Pattern Underneath Complete Denture with Various Posterior Teeth form: An In Vitro Study

To evaluate the pattern of stress dissipation underneath the complete denture with various angled posterior teeth in both maxillary and mandibular arch. A 3D finite element models of residual ridge, mucosa, denture base in the coronal section were created from the dentures obtained from a patient, which were scanned and modeled. The coronal portion of the teeth was altered to stimulate the cuspal inclination of 0°, 20° and 33°, thus making the models. Special area of interest in bone, denture were selected to record the stresses. An vertical static load of 100N was applied through the mandibular model to the maxillary model. von Mises stresses developed in all the models were interpreted. Statistical analysis for comparison of stress values with different variables (0°–20°, 0°–33°, and 20°–33°) in various predefined areas of coronal section model was done using Student’s t test (paired). Stress of greater magnitude were observed with cuspal teeth i.e. 33° and 20°, where as 0° showed slightly less magnitude of stresses.     

球帽覆盖义齿粘固球帽前后咬合特征变化研究

目的：定量研究球帽附着体覆盖全口义齿（complete overdenture,COD）修复后咬合接触分布的变化,初步说明球帽附着体对义齿影响,为临床调（牙合）提供理论依据.方法：采用T-ScanⅡ咬合分析仪进行体内咬合分布特征及咬合时间的测定.全口义齿及球帽附着体覆盖全口义齿修复后患者各16例.球帽覆盖义齿修复患者于粘固球帽前,粘固后3月进行咬合检测,全口义齿修复患者于义齿修复3月后检查咬合分布.记录咬合力中心（center of force,COF）前后位移值（Y）,咬合力前后向分布比率,咬合时间.结果：双侧球帽覆盖义齿粘固球帽后咬合力逐渐增加,高于同期全口义齿,差异有统计学意义（P＜0.05）.球帽覆盖义齿粘固3个月时咬合中心较粘固前前移,与同期全口义齿咬合中心差异有统计学意义（P＜0.05）.全口义齿咬合时间为0.29sec,双侧球帽粘固球帽前为0.27sec,粘固3个月时双侧球帽为0.25sec.差异无统计学意义（P＞0.05）.结论：粘固球帽前覆盖义齿与全口义齿咬合分布状态相似.球帽覆盖义齿粘固球帽3个月内咬合力增大,前牙咬合接触增多,咬合中心前移明显.提示临床对球帽覆盖义齿应在双侧咬合分布平衡同时,注意调整前牙咬合分布.     

A Practical Method for Chairside Repair of Debonded Porcelain Denture Teeth

The bonding of porcelain denture teeth to polymethylmethacrylate remains a clinical problem. In this article an alternative chairside method, based on silica coating and silanization for adhesion of denture tooth porcelain to polymethylmethacrylate is described.     

Replace系统种植义齿的设计与制作

目的：探讨Replace种植系统的义齿修复。方法：用Replace种植系统对30例38枚种植体进行义齿修复。其中前牙区23枚种植体,后牙区15枚种植体。结果：经过半年至两年的临床观察,无一例种植义齿修复失败,X线示,种植体周围无透影区,种植体颈部边缘骨吸收在正常范围。结论：合理的修复设计,规范、精确的制作技术是种植义齿修复成功的重要保证。