Fixed partial dentures opposing complete dentures

When fixed partial dentures are indicated in an arch opposing a complete denture, it is best to develop the occlusal surfaces of the fixed restorations at the same time that the opposing denture teeth are arranged in wax to permit greater flexibility and reduce the compromise in developing bilateral balanced occlusion. This article describes the development of bilaterally balanced occlusion between casting patterns for fixed partial dentures and a complete denture. The technique emulates the ease of arranging maxillary and mandibular denture teeth and can be used to develop fixed restorations with metal or porcelain occlusal surfaces. Porcelain occlusal surfaces are described because the use of porcelain is more technique sensitive.     

Maximizing mandibular prosthesis stability utilizing linear occlusion, occlusal plane selection, and centric recording.

The stability of mandibular complete dentures may be improved by reducing the transverse forces on the denture base through linear (noninterceptive) occlusion, selecting an occlusal plane that reduces horizontal vectors of force at occlusal contact, and utilizing a central bearing intraoral gothic arch tracing to record jaw relations. This article is intended to acquaint the reader with one technique for providing stable complete denture prostheses using the aforementioned materials, devices, and procedures.     

Symptoms of mandibular dysfunction in complete denture wearers

Recent epidemiological studies have shown that symptoms of mandibular dysfunction are very common, but prosthodontists have thought that complete denture wearers are spared such complications. However, in recent reported series of patients who have sought advice for mandibular dysfunction complete denture wearers have been included. According to epidemiological data individuals with few remaining natural teeth had more symptoms of dysfunction than those with most of their natural teeth, and complete denture wearers had more symptoms of mandibular dysfunction than subjects with natural teeth. Mandibular and temporomandibular joint dysfunction symptoms have a heterogeneous background, but occlusal instability is an important aetiological factor. In complete denture wearers with mandibular dysfunction, symptoms often disappear after improvement of the occlusion.     

Modification of denture teeth for improved occlusal stability of a maxillary removable complete denture opposed by a mandibular implant-supported fixed complete denture: A clinical report

Wear of artificial teeth is the most common complication associated with an implant-supported fixed complete denture (ISFCD). This wear alters the occlusal scheme, with loss of eccentric occlusal balance and vertical dimension of occlusion (VDO). This clinical report describes the fabrication of a new maxillary removable complete denture opposing an existing ISFCD with occlusal modifications. Both prostheses received splinted zirconia crowns cemented with composite resin cement.     

全口义齿平面前点确定方法的光弹性研究

目的 探讨全口义齿平面前点的确定方法与光弹性效果。方法 选择2015年2月—2017年7月到我院诊治的10例牙列缺失患者作为研究对象,同时制作了由哥特式弓轨迹顶点(义齿A组)、自然咬合法(义齿B组)确定平面前点的全口义齿,测定义齿的咬合指标、光弹性效果与应力情况。结果 调前,义齿A组的咬合接触时间多于义齿B组,左右侧力百分比差值与力中心距离到中线的距离少于义齿B组,对比都有统计学意义(P＜0.05);调后两组上述指标对比都无统计学意义(P＞0.05)。义齿A组与义齿B组测定都显示牙尖工作斜面与平面的夹角呈越向远中越大的趋势,相邻角度差值也有向远中增大的趋势,组间对比无差异(P＞0.05)。义齿A组与义齿B组模型的光弹性材料符合模型实验的基本要求,两组的舌向集中的正中与前伸最大应力值均小于解剖(P＜0.05),在两组对比无差异(P＞0.05)。结论 采用哥特式弓轨迹顶点与自然咬合法确定全口义齿平面前点能维持义齿平衡,其中哥特式弓轨迹顶点确定平面前点的全口义齿的咬合能达到更好的咬合关系。     

A study of the occlusal plane orientation by intra-oral method (retromolar pad)

Summary Reliability of the intra-oral method which orientates the occlusal plane to terminate at the upper level of the retromolar pad was studied. Thirty individuals all with natural teeth and 34 complete denture wearers participated in the study. Stone casts were mounted in the S.A.M. 2 articulator by a quick mount face bow transfer. The angle between the occlusal plane and the articulator horizontal plane was measured in both groups. The angle was 9.42°± 4.1° in dentate individuals and 8.53°± 2.8° in complete denture wearers. No statistically significant difference was found between the groups ( t =0.72, P > 0.05). Therefore, the method can be advocated for a wide clinical use, as it is a simple method and places the artificial occlusal plane very close to the position of the natural plane of occlusion.     

Chewing performance and occlusal contact area with the shortened dental arch

The aim of this study was to investigate the effect of the loss of posterior teeth on the effectiveness of mastication. To evaluate this, chewing performance and occlusal contact area were investigated in 10 edentate subjects having implants stabilising a mandibular overdenture. A copy of the original lower denture was made for each subject, with removable teeth, which could be separated to convert a complete dental arch to a shortened dental arch, an extremely shortened dental arch, or a broken dental arch. Both post canine occlusal contact area and chewing performance demonstrated significant differences between the different arches. It was concluded that chewing performance is reduced by removing posterior teeth from implant stabilised mandibular complete dentures.     

Occlusal contacts of edentulous patients with mandibular hybrid dentures opposing maxillary complete dentures.

The purpose of this study was to evaluate differences between the occlusal contacts of edentulous patients with mandibular implant-supported hybrid dentures opposing maxillary complete dentures and those of patients with conventional maxillary and mandibular complete dentures. Six parameters related to occlusion were measured in the 2 groups (n = 40 for each group) using pressure-sensitive film. The mean values generated by each test group for each parameter were compared using a t test. Pearson's correlation coefficients between occlusal force, age, and time in function were examined. Occlusal force and area in the implant denture wearers were larger than those in the conventional denture wearers. No significant difference was seen in occlusal force balance between the left and right sides. The center of occlusal load in the implant denture wearers was more anterior. The maxillary denture may become more unstable in implant denture wearers. It is suggested that the stability and retention of a maxillary denture be checked and the occlusion be adjusted more frequently in the hybrid denture wearer than in the conventional denture wearer.     

Occlusal Plane Location in Edentulous Patients: A Review

Occlusal plane orientation is an important factor in the construction of a complete denture. Occlusal plane could be oriented using landmarks in the mandibular arch as well as in the maxillary arch. In the mandibular arch there are few landmarks which could be used to orient the occlusal plane like the retromolar pad, corner of the lips (lower lip length) whereas the maxillary arch has a number of landmarks, of which the ala-tragal line is the most commonly used and the same being the most controversial. In the following article different landmarks and its accuracy for orientating the occlusal plane in an edentulous subject as studied by various authors has been discussed.     

Occlusal schemes of complete dentures--a review of the literature

Occlusal scheme is defined as the form and the arrangement of the occlusal contacts in natural and artificial dentition. The choice of an occlusal scheme will determine the pattern of occlusal contacts between opposing teeth during centric relation and functional movement of the mandible. With dentures, the quantity and the intensity of these contacts determine the amount and the direction of the forces that are transmitted through the bases of the denture to the residual ridges. That is why the occlusal scheme is an important factor in the design of complete dentures. Three occlusal schemes are viewed in this review: bilateral balanced occlusion, monplane occlusion, and linear occlusion scheme. Each scheme represents a different concept of occlusion. Comparisons between these schemes are also reviewed and analyzed. The reasoning underlying the bilateral balanced occlusion scheme is that stability of the dentures is attained when bilateral contacts exist throughout all dynamic and static states of the denture during function. Anatomic teeth are used: the upper anterior teeth are set to satisfy aesthetics, and the posterior teeth are arranged in a compensatory curve and a medial curve. This scheme is adequate for well developed residual ridges, with skeletal class I relation. With highly resorbed residual ridges, the vectors of force that are transmitted through anatomic cusps will dislodge the lower denture and thus impair the comfort and efficiency of mastication experienced by the patient. In order to accommodate to the special needs posed by highly resorbed residual ridges and skeletal relations that are not class I, the monoplane scheme of occlusion was designed. This scheme consists of non anatomic (cuspless) teeth, which are set so that the anterior teeth provide the aesthetics, the premolars and the first molars are used for chewing, and the second molars do not occlude (although sometimes they are specifically used to establish bilateral contacts in lateral movements). Linear occlusion scheme occludes cuspless teeth with anatomic teeth that have been modified (bladed teeth) in order to achieve linear occlusal contacts. Linear contacts are the pin-point contacts of the tips of the cusps of the bladed teeth against cuspless teeth that create a plane. The specific design of positioning upper modified teeth on the upper denture and non anatomic teeth on the lower one is called lingualized occlusion. It is characterized by contacts of only the lingual (palatinal, to be more accurate) cusps of the upper teeth with the lower teeth. The lingualized occlusal scheme provides better aesthetics than the monoplane occlusion scheme, and better stability (in the case of resorbed residual ridges) than bilateral occlusion scheme of anatomic teeth. The results of studies that compared different occlusal schemes may well be summarized as inconclusive. However, it does seem that patients preferred anatomic or semi-anatomic (modified) teeth, and that chewing efficiency with anatomic and modified teeth was better than with non anatomic teeth. Similar results were found in studies of occlusal schemes of implant-supported lower dentures opposed by complete upper dentures. Conclusion: There isn't one occlusal scheme that fits all patients in need of complete dentures, in fact, in many cases more than one occlusal scheme might be adequate. Selection of an occlusal scheme for a patient should include correlation of the characteristics of the patient with those of the various occlusal schemes. The characteristics of the patient include: height and width of the residual ridge, aesthetic demands of the patient, skeletal relations (class I/II/III), neuromuscular control, and tendency for para-functional activity. The multiple characteristics of the occlusal schemes were reviewed in this article. Considering all of those factors in relation to a specific patient, the dentist should be able to decide on the most suitable occlusal scheme for the case.     

Evaluation of the utility of cephalometric parameters in constructing complete denture. Part I: placement of posterior teeth

Various types of parameters, including cephalometric ones, have been used in the construction of complete denture. This study aimed to evaluate the utility of cephalometric parameters for this purpose. The position of the posterior teeth in a group of 42 edentulous patients, successfully rehabilitated with complete denture according to clinical parameters, was evaluated by cephalometrics. The following were determined: vertical dimension of occlusion (VDO); orientation of the occlusal plane; and subdivision of the denture space. The cephalometric parameters do not correspond to the clinical positioning of the posterior teeth in successful rehabilitation with complete denture.     

Restoration of inadequate occlusal face height by using resin bonded to etched metal removable prosthesis

The resin bonded to etched metal casting of a removable partial denture was used anteriorly in combination with posterior acrylic resin teeth to restore patients with mandibular overclosure. The procedure is simple, esthetic, conservative, inexpensive, and not time-consuming. Patients maintained their new occlusal facial height with normal functional activity. The remaining natural teeth showed no signs of changes in 6 months in either opposing tooth structure or the periodontum.     

A discussion of some factors of relevance to the occlusion of complete dentures

There exists general agreement that in the construction of complete dentures the accurate positioning of the plane of occlusion is essential for correct denture function. Yet rarely does a prosthodontist give detailed instructions concerning the positioning of this plane to the technician who is to set the teeth. In this paper the three-dimensional location and form of the occlusal plane is discussed. For both anatomical and mechanical reasons the author favours the use of the mandibular rather than the maxillary record rim as the clinical determinant of the level of the artificial occlusion. A change in the method of setting the face-bow is recommended to allow for the difference between the cranial Frankfort plane and the axis-orbital plane of the articulator. Arguments are advanced to support the proposal that artificial teeth should be set to an intercuspal location forward of centric relation; and that the form of the antero-posterior compensating curve of the artificial dentition should be determined by the clinician before the teeth are set to the registration rims.     

Assessment of tooth displacement during the cast-free digital processing of milled dentures

Statement of problemDenture tooth displacement may have a significant impact on denture occlusion. This aspect has seldom been investigated, especially for digital denture processing techniques.PurposeThe purpose of this clinical study was to evaluate the accuracy of tooth position with milled digital dentures processed without physical casts.Material and methodsTen maxillary and 10 mandibular dentures designed from intraoral scans, milled, and processed without physical casts were investigated. The standard tessellation language (STL) files of the digitally designed dentures were compared with the scan of the dentures after processing (milling the denture base, milling teeth in a complete arch, and then bonding teeth into the base). The STL files were superimposed by using a surface-matching software program. After a preliminary alignment, the STL meshes were trimmed and reoriented; then, the final alignment was carried out by using the cameo surface. Six reference points (the mesiobuccal cusp on the most distal molar, the canine cusp, the middle of the incisal edge of the central incisor on both the left and the right side) were selected to measure tooth displacements along the X-, Y-, and Z-axes, corresponding (from the preliminary reorientation) to anteroposterior, mediolateral, and occlusal displacement, respectively. Tooth position accuracy was assessed by using median and interquartile range values. Univariate and multivariate statistical analyses were used to investigate the significance of the extent of displacements, as well as differences among displacement directions, reference teeth, side, and denture arch type (α=.05).ResultsOnly the median (0.2 mm; interquartile range: 0.27 mm) occlusal displacement was significantly different from zero. A generalized estimated equation model addressing occlusal displacement as a dependent variable showed no significant effect of tooth type, side, or denture arch type, either alone or in combination.ConclusionsThe tooth position of both maxillary and mandibular milled digital dentures processed without physical casts was accurate in the anteroposterior and mediolateral directions. Occlusal displacement seemed to be within the range of clinical acceptability; its consistency throughout the arch allowed optimization or compensation at the design or manufacturing step.     

Replacement of a mandibular implant-fixed prosthesis with an implant-supported overdenture to improve maintenance and care

PatientsA 69-year-old woman presented to the Osaka University Dental Hospital. She had two chief complaints, (a) food accumulation under the lower teeth and (b) poor maxillary denture retention while eating. On clinical examination the patient presented with a maxillary complete denture and fixed mandibular implant prosthesis. For preventing food accumulation under the fixed implant prosthesis and to keep the maxillary denture stable by providing posterior occlusal contact for bilaterally balanced occlusion, the use of a mandibular implant-supported overdenture with self-adjusting magnetic attachments provided a prosthetic solution for this patient. After provided the new dentures, the patient was pleased and was comfortable with the aesthetic, stability and retention of the dentures. There were no discernable clinical or radiographic changes after 1 year of use.DiscussionTo prevent food accumulation beneath the fixed implant prosthesis and maintain the stability of the maxillary denture by providing posterior occlusal contact for bilaterally balanced occlusion, a mandibular implant-retained overdenture with magnetic attachments was used to provide a prosthetic solution for this patient.ConclusionIn this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced into an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses.     

The effects of salivas on occlusal forces

Contacting surfaces of opposing teeth produce friction that, when altered, changes the contact force direction and/or magnitude. As friction can be influenced by several factors, including lubrication and the contacting materials, the aim of this study was to measure the occlusal load alterations experienced by teeth with the introduction of different salivas and dental restorative materials. Pairs of molar teeth were set into occlusion with a weighted maxillary tooth mounted onto a vertical sliding assembly and the mandibular tooth supported by a load cell. The load components on the mandibular tooth were measured with three opposing pairs of dental restorative materials (plastic denture, all‐ceramic and stainless steel), four (human and three artificial) salivas and 16 occlusal configurations. All lateral force component measurements were significantly different (P < 0·0001) from the dry (control) surface regardless of the crown material or occlusal configuration, while the effects of the artificial salivas compared to each other and to human saliva depended on the crown material.     

Occlusal force pattern in dentitions with mandibular implant-supported fixed cantilever prostheses occluded with complete dentures

Naturally occurring axially directed closing and chewing forces were measured in ten patients with mandibular fixture-supported cross-arch prostheses occluding with maxillary complete dentures. The design of the mandibular constructions was characterized by bilateral posterior two-unit cantilevers. The forces were measured using eight miniature strain gauge transducers mounted in the maxillary denture and evenly distributed over the tooth arch. Forces were thus measured at four occlusal contact points over the fixture segment and over each of the four posterior cantilever units simultaneously, giving a detailed picture of the force distribution. The total forces developed during maximal closing in habitual occlusion and chewing were of the same magnitude as previously reported for patients with tooth-supported cross-arch fixed partial dentures occluding with natural teeth using the same method. Contradictory to previous findings, in dentitions with comparable tooth-supported cantilever constructions occluding with natural teeth, local closing and chewing forces increased bilaterally in the distal direction. On average, 70% of the forces were borne by the cantilevers and 30% by the fixture-supported segment of the prostheses.     

T—ScanⅢ数字化咬合分析系统在全口义齿调[牙合]中的应用

目的：探讨T-ScanⅢ数字化咬合分析系统结合咬合纸印记指导全口义齿调[牙合]的效果。方法：选取门诊无牙颌患者21人,常规制作全口义齿,去除明显的咬合干扰点,戴入2周后,指导患者从下颌姿势位（MPP）咬合达牙尖交错位（ICP）。用T—ScanⅢ数字化咬合分析系统分析诊断患者的咬合情况,结合咬合纸印记,对早接触点及胎力异常大的接触点进行调[牙合],达到牙尖交错位的广泛接触,对调胎前后的咬合接触时间、后牙接触点、后牙接触面积,胎力分布平衡度进行比较,同时进行患者满意度问卷调查。结果：21例患者在调[牙合]前后的咬合接触时间明显缩短短（P〈0．05）,后牙接触点明显增加（P〈0．05）,后牙接触面积增加,[牙合]力分布平衡度明显减小（P〈0．05）;患者满意度〉9．0分。结论：咬合纸印记结合T-Scanm咬合分析仪指导全口义齿调[牙合]取得满意的临床效果。     

Effect of Complete Dentures on Craniofacial Growth of an Ectodermal Dysplasia Patient: A Clinical Report

The aim of this clinical report was to observe the effect of complete dentures on craniofacial growth and development of an ectodermal dysplasia (ED) patient. A complete anodontia patient diagnosed with ED was successfully rehabilitated with conventional complete dentures at the ages of 5, 8, and 10 years. Three sets of complete dentures were made with age‐appropriate denture teeth and a bilaterally balanced lingualized occlusal scheme. Periodic follow‐up and adjustment when needed was done to maintain proper oral function and esthetics. Serial cephalometric analysis exhibited a marked restriction of forward growth at the anterior nasal spine (ANS) point between 5 and 10 years of age, although there was little change from average in the anteroposterior length of the mandibular body and the height of the mandibular ramus. So, while maxillary growth was reduced, mandibular growth did not significantly change. Cast analysis showed that the increase in arch length was greater than in arch width for both the maxilla and mandible. There was little increase in alveolar ridge height in the anterior region but a considerable increase in the height of the alveolar ridge in the middle and the posterior region. Our findings concluded that the absence of teeth did not affect the growth of the jaws, and it is probable that the denture flange did not arrest the jaw growth, but rather improved the masticatory function by providing good denture stability and retention.     

Wear of resin denture teeth in partial removable dental prostheses

PurposeTo investigate occlusal wear of resin denture teeth in partial removable dental prostheses worn by partially edentulous patients.MethodsThirty patients with partial removable dental prostheses were included in the study. Thirty-two patients with complete dentures served as a reference group. Occlusal wear after two years was evaluated indirectly using gypsum casts and a three-dimensional laser-scanner device. Overall wear of complete occlusal surfaces and maximum wear of occlusal contact areas were measured. Patient and prosthesis data were analyzed using univariate and multiple linear mixed models.ResultsOverall wear of denture teeth in partial removable dental prostheses was 91 (SD 85) μm, and maximum wear of occlusal contact areas was 329 (SD 204) μm (means and standard deviations). Average and maximum wear values for teeth in complete dentures were both lower than those for teeth in partial removable dental prostheses. However, differences between wear of different types of denture did not reach statistical significance after adjustment for gender, type of tooth, dental status of the opposing jaw, and antagonist material. Statistical analysis revealed that wear was greater for denture teeth occluding with ceramic crowns and/or fixed partial dentures as antagonists.ConclusionsResin denture teeth in partial removable and complete dental prostheses are subjected to clinically important occlusal wear that might destabilize occlusion and cause further problems. Patient-related factors and dental status affect wear behavior and should be taken into consideration when treating patients with removable dentures.