Clinico-statistical observation of various prosthetic restorations at the Prosthetic Department, Asahi University Hospital. 3. Frequency of various prosthetic restorations inserted for the duration from April 1986 to March 1987

The statistics for prosthetic restorations used at the Prosthetic Department of Asahi University Hospital from April 1986 to March 1987 were compared with those obtained in earlier period (April 1983 to March 1984). A total of 2,360 prosthetic restorations were used. This was a 12.5% decrease compared to the previous period. No significant sex-related difference was found in the number of restorations used. The number of prosthetic restorations was decreased in patients in their forties who had the most restorations in the previous period. During the period investigated in this study, the number of prosthetic restorations was highest in the patients in their fifties and lowest in those in their eighties. By sex, prosthetic restorations were used most frequently in males in their fifties and in females in their thirties. The prosthetic restorations used during this period had almost the same proportions as in the previous period. Most frequently used were full cast crowns followed by facing crowns, as were during the previous period. The former amounted to 36.1% and the latter to 22.1%. Full dentures were the least used restorations and amounted to 5.2% of all the prostheses. The use of facing crowns had considerably decreased in patients in their forties, although this age group had the highest frequency of use during the previous period. Full cast crowns were most frequently used in patients in their thirties, removable partial dentures in those in their fifties and total dentures in those in their seventies.     

Prognosis for Abutment Teeth of Removable Dentures: A Retrospective Study

PURPOSE: This retrospective study evaluates the clinical success of conical crown-retained removable dentures. MATERIALS AND METHODS: Ninety-seven patients were treated with 97 dentures at the University of Frankfurt, Department of Prosthodontics, between 1993 and 2000. The average observation period was 4.9 +/- 2.8 years. The dentures were supported by 445 natural abutment teeth. To evaluate the long-term success of the restorations, the variables abutment loss, tooth mobility, mean probing depths, and radiological bone loss were used. Data were obtained by one clinical examiner at baseline, by systematic evaluation of patient records, and at clinical re-examinations. Survival-time methods were used to analyze time-to-event data. Specifically, the Cox model with frailty term was applied to account for correlations between intra-patient survival data. Thirty abutment teeth had to be extracted during the observation period. RESULTS: Statistical analysis showed no significant effects of the variables tooth mobility (p= 0.42), mean probing depths (p= 0.23), and radiological bone loss (p= 0.59) on the time to tooth extraction. For the non-extracted abutment teeth significant changes during time for the variables tooth mobility (p < 0.0001) and radiological bone loss (p= 0.0240) were observed. CONCLUSION: Removable partial dentures retained by conical crowns have a favorable clinical prognosis.     

Statistical analysis of fabrication of fixed and removable partial dentures]

A statistical survey based on laboratory records was performed on the number of fixed and removable partial dentures fabricated at the dental hospital of Tokyo Medical and Dental University from April 1 to September 30, 1997. A comparison was also performed with a previous survey, which had been carried out in 1986, in order to detect any change and possible alterations in the near future. From the findings of this statistical survey, the conclusions were as follows: 1. A total of 2,478 fixed and removable partial dentures were fabricated during the six month period in 1997. 2. The 3-unit fixed partial denture (bridge) was most common (63.1%) and the number of bridges decreased as the number of units increased. 3. For the single missing tooth, a fixed bridge was more popular (81.0%) than a removable partial denture. 4. For two missing teeth, there was no difference between the number of fixed bridges and removable partial dentures. 5. The percentage of fixed and removable partial dentures, which were not covered by health insurance, decreased to a large extent in comparison with the survey in 1986.     

Conservative and prosthetic rehabilitation procedures in the dentition of old people.

The therapeutic possibilities of conservative and prosthetic rehabilitation procedures are set out in this survey. In particular the aim was to find out whether these are suitable for retaining functional dentition into old age. The anatomical characteristics (Figs. 1 and 3) and secondary dysgnathic alterations of the dentition in the period of senescence make dental therapy considerably more difficult. The tooth-coloured filling materials do not behave as permanently in the mouth as could be wished. They are unsuitable for use in posterior teeth, and are in urgent need of improvement. The amalgam filling should still be regarded as the agent of choice for treatment of the cheek teeth, although cast precious metal inlays have been successful over a long period of time (Fig. 6). Too little use is made of veneer crowns in the anterior area with increasing age (Fig. 7), although the prospect of long term success is good. It was possible to establish statistically that tooth-coloured plastics are inferior to ceramic and metal ceramic crowns because of the greater retention of plaque. Ceramic should accordingly be preferred even with bridges in the anterior area. The replacement of missing teeth with removable partial dentures is the typical method of dental treatment for the period of senescence (Figs. 10-12). An attempt was made by bringing together various principles of planning and construction to lay down guidelines for dentures in older patients. With prosthetic care the fact that there are large differences in the physical and mental vitality of the older person, and that vitality frequently decreases rapidly for the most varied reasons, should not be overlooked. Even at this stage dentures should still prove functional.     

老年人牙缺失临床修复治疗的分析

目的了解老年修复患者的口腔情况及修复特点。方法对1 166例60岁以上老年人牙缺失患者作修复治疗,分析缺牙及修复情况。结果1 166例患者平均缺牙10.25颗。牙缺失数上领>下领,磨牙>双尖牙>切牙>尖牙。1 166例患者中1 120例作可摘义齿修复,其中游离端缺失约占58%0 46例作固定义齿修复。结论老年修复患者具有缺牙数目多,游离端缺失多,余牙磨耗严重,食物嵌塞多,余留牙松动及残根多等特点;修复以可摘义齿为主,可适当行固定义齿修复。修复治疗时尽量发挥尖牙、已治疗的残根及健康第三磨牙的作用。     

Statistical survey of prosthetic restorations--fixed and removable prosthesis]

This is a continued report on the statistical classification of the prosthetic restorations placed in the outpatients in the Tokyo Medical and Dental University Hospital. The data were collected from the laboratory records during the period of January to June of 1986. The results are summarized as follows: 1. Total of 419 bridges, consisting of nearly the same number in the maxillary and mandibular units, were fabricated. A wide variety of designs was observed for those not covered by the health insurance. 2. Approximately 83% of the 265 complete dentures were covered by the health insurance. The number of the maxillary units was slightly more than that of the mandibular units, which was similar to the data collected about 20 years ago. 3. Seven hundred and fifty-four partial dentures were placed and approximately 45% of these were covered by the health insurance. 4. Various designs were observed in the 'Konus-Kronen' type of prosthesis. They were assumed to be applied not only for the restoration of the edentulous areas, but also for the splinting of the remaining teeth. 5. Fixed bridges were placed in more than 90% of the cases with single tooth loss. However, partial dentures were more frequently used than the fixed bridges for the restoration of the two-tooth loss.     

Orthodontic and prosthetic rehabilitation of unilateral free-end edentulous space

Most patients prefer fixed dentures, even in the presence of uni and bilateral free-end saddle. The most suitable treatment for this is an implant or implant-supported prosthetic restoration. A combined prosthetic and orthodontic treatment with distalization of a posterior tooth towards the edentulous region is an alternative approach. This study involved a 34.3 year old female patient who had a free-end edentulous space on the left mandibula and missing 1st and 3rd molars on the right mandibula. The patient was offered both a removable partial denture and implant treatment options. A detailed explanation of her situation and suitable treatments were given but she refused both options. Therefore, an alternative combined treatment involving prosthodontic and orthodontic disciplines was performed. The second premolar tooth was distalized orthodontically and used as a distal bridge abutment. After 65 months, prosthetic restoration was functional and abutment teeth and periodontium were pathology free, and the patient was satisfied with the results.     

Frictional telescopic crowns in severely reduced dentitions: a 5-year clinical outcome study

Clinical outcomes for frictional telescopic crowns supporting removable prostheses in patients with severely reduced dentitions with one to three remaining teeth per arch have been inadequately documented. Seventy-four patients with severely reduced dentitions received 82 telescopic removable partial dentures that were supported by 173 frictional telescopic crowns. The recorded individual telescopic abutment survival rate over a 60-month period was 80.6%. This observation was significantly influenced by sex and tooth vitality and mobility (Kaplan-Meier). The risk of loss of telescopic crowns was significantly influenced by sex, arch, vitality, and abutment tooth distribution (Cox regression). Telescopic removable partial dentures were proven to be a favorable treatment concept for severely reduced dentitions in the selected group of patients.     

Clinical evaluation of abutment teeth of removable partial denture by means of the Periotest method

Prosthodontics should be one of the means of establishing conditions for the maintenance of periodontal health. The forces applied to the abutment teeth and their effects are very important considerations in the design and construction of the removable partial dentures. This 6-month follow-up clinical study evaluated the degree of mobility of abutment teeth of distal extension and tooth supported removable partial dentures by using Periotest. Two types of clasp design were selected for evaluation. In cases with unilateral and bilateral distal-extension, a clasp design including a T clasp of Roach retentive arm, a rigid reciprocal arm and a mesial rest were used. For the abutments of tooth-supported removable partial dentures, a second clasp design with a cast circumferential buccal retentive arm, a rigid reciprocal clasp arm and a rest adjacent to the edentulous ridges was selected. A total of 68 abutment teeth was analysed. Periotest values were made at the time of denture placement (control) and at 1, 3 and 6 months after the denture placement. The statistical analysis was performed using Friedman test. All analysis was performed at a 0.05 level of significance. The results revelled that no significant changes in tooth mobility were observed during the 6-months follow-up (P > 0.05). In conclusion, our findings suggest that adequate oral hygiene instructions, careful prosthetic treatment planning and regular recall appointments play an important role in preventing changes in abutment tooth mobility caused by removable partial denture placement.     

Restoration of four missing upper-incisors with fixed bridges. I. A survey of fifty fixed bridges

Four missing upper-incisors are usually restored in practice by both ways, fixed bridges and removable partial dentures. A survey of fifty fixed bridges for this type of missing teeth was conducted, in order to find out some points of caution when bridges are selected. The following results were obtained: 1. The average age of patients was 47 years old and the average life span of bridges was about 10 years. 2. Six-tooth fixed bridges extending from cuspid to cuspid, that is, bridges with two abutment teeth made up 70% of all bridges. 3. Band-crowns were used in the highest frequency (50%) retainers. 4. Various kinds of disorders were detected in the gathered bridges. Particularly recurrent caries and alveolar bone loss around the abutment teeth were remarkable. 5. Three-quarter crowns became uncemented in high frequency and therefore seemed to provide inadequate retention. 6. Regarding the contact of pontic with the ridge tissue, the effect of the material used was predominant to the form. 7. The upper incisors of pontic could play the role of guidance during protrusive movements with very little occurrences of disorder. 8. The occlusal support index of under 8 indicated a high possibility of various disorders afterwards.     

Resin-bonded prostheses for posterior teeth.

This study evaluated fixed partial dentures bonded with resin to dentin on posterior teeth with minimal tooth preparation. The patients included were missing at least one premolar or first molar. The abutment teeth next to the modification spaces were moderately restored with MOD or class II restorations on most of the teeth. A total of 20 patients with 23 fixed partial dentures were included in the study. After removal of existing restorations, the abutment teeth were prepared to eliminate undercuts on the perimeter of the preparations. Undercut areas within the preparation were not filled but were blocked out later in the laboratory. The fixed partial dentures employed inlays as retainers for a metal ceramic pontic. The metal framework was cast in a high noble gold alloy. The areas of the retainers to be bonded were treated with the Kulzer Silicoater method. Immediately before cementation, enamel was etched and exposed dentin was treated with Gluma. Kerr's resin bonded bridge cement was used for cementation. Patients were recalled after periods of 1 week, 1 month, 6 months, 1 year, 2 years, and 4 years for evaluation. None of the restorations lost retention and no major adverse effects were observed in the 4-year follow-up period.     

Statistical analysis of fabrication of indirect single restorations]

A statistical survey based on laboratory records was performed on the number of indirect restorations fabricated at the dental hospital of Tokyo Medical and Dental University from April 1 to September 30, 1997. A comparison was also carried out with a previous survey, which had been carried out in 1986, in order to detect any change and possible alterations in the near future. Based on the results of this statistical survey, the conclusions were as follows: 1. A total of 9,126 indirect restorations were fabricated during the six month period in 1997; among them, 8,007 (87.7%) restorations were covered by health insurance and 1,119 (12.3%) restorations were not. 2. The most common restoration was the cast post and core (28.6%), followed by full crowns (18.5%) and removable partial dentures (15.6%). On the other hand, the least number were post crowns (0.03%) and resin jacket crowns (0.2%). 3. When making a comparison with the data in 1986, an increase in the number of removable partial dentures and a decrease in the number of inlays were the most distinctive features. 4. For anterior teeth, resin-veneered crowns were most common, especially for lower teeth. The percentage of restorations, which were not covered by health insurance, decreased from 45.0% (in 1986) to 12.3% (in 1997).     

Statistical analysis of the fabrication of fixed and removable partial dentures (in 2002)

A statistical survey based on laboratory records was performed on the number of fixed partial dentures and removable partial dentures fabricated at the dental hospital of Tokyo Medical and Dental University from April 1 to September 30, 2002. A comparison was also performed with a previous survey that had been carried out in 1997 to detect any change and possible alternations in the near future. From the findings of this statistical survey, the conclusions were as follows: 1. A total of 2,656 fixed and removable partial dentures were fabricated during the six-month period in 2002. 2. The 3-unit fixed partial denture was most common (64.0%), and the number of fixed partial dentures decreased as the number of units increased. 3. For a single missing tooth, a fixed partial denture was more popular (80.8%) than a removable partial denture. 4. For two missing teeth, there was little difference between the number of fixed and removable partial dentures. In the anterior region, fixed partial denture was more common, while in contrast, in the posterior region, removable partial denture was more common.     

Fabricating Crowns to Fit Existing Removable Partial Dentures: An Illustration of Two Techniques

The prosthetic treatment of a structurally compromised abutment tooth supporting a removable partial denture may present a variety of restorative modalities. Ideally, a surveyed crown is made for the individual tooth, which is later followed by a new removable partial denture fit to the contours of the crown. Frequently, however, the removable partial denture is clinically acceptable, and remaking the prosthesis is not indicated. In these cases, the crown can be made to fit the existing removable partial denture. Fabricating crowns to fit existing removable partial dentures can be accomplished using a direct method, an indirect method, or combinations of these techniques. Direct techniques traditionally use acrylic resin and inlay wax intraorally to develop a custom pattern that captures the contours of the clasp assembly. Indirect techniques use a pick-up impression to allow the crown pattern to be waxed against the denture framework on a cast in the laboratory. Combination methods use either a direct-indirect or indirect-direct approach. The direct-indirect method develops the preliminary resin pattern directly on the tooth and finalizes the contours in wax on a master cast. The indirect-direct technique initiates a crown pattern on a die and completes it either intraorally or on the die after the intraoral refinements. This article reviews the literature for methods of fabricating surveyed crowns under existing removable partial dentures. Additionally, two cases are presented that illustrate an indirect and combination direct-indirect technique for making the restorations.     

The use of crowns to modify abutment teeth of removable partial dentures. 1. Introduction and partial denture design.

Major modifications of abutment teeth can only be achieved by the use of restorations. Full crowns enable these modifications to be made in conjunction with ideal design and location of the components of removable partial dentures. Part 1 of this paper discusses these relevant components while part 2 will describe the clinical and laboratory procedures.     

The role of the prosthodontist in the treatment of periodontal disease

The inter-relationships between the periodontal situation of a patient and a prosthetic appliance should be regarded in particular from the aspect of oral hygiene. Creating or maintaining a high standard of oral hygiene is thus the joint objective characterizing cooperation between the periodontist and the prosthodontist. The tasks falling to the prosthodontist during initial therapy are: removal and temporary replacement of restorations that are not conducive to good oral hygiene, temporary replacement of teeth with hopeless prognoses, and temporary prosthetic planning in conjunction with the periodontist. In the phase of surgical periodontal treatment, the creation of new attachments should be accompanied by morphologic corrections; these are essential to the oral hygiene of patients with prosthetic appliances. The prosthodontist has therefore to advise the periodontist on what corrections are desirable and where. This applies firstly to gingival corrections at abutment teeth and secondly to mucosal corrections on the edentulous alveolar ridge. On conclusion of the periodontal treatment, the prosthodontist will have to come to terms with three problems: the indication for prosthetic treatment, the decision between fixed bridges and removable partial dentures, and the periodontal problem zones occurring with crowns and bridgework. The indications for prosthetic treatment can now be more restricted, following recent findings on oral function with shortened dental arches. When deciding between fixed bridges and removable partial dentures, it is the oral hygiene aspect that is decisive. In existing or threatened free-end situations preference should be given to bridgework. This can be implemented with: cantilever bridges, bridges abutted at each end by the distal movement of a premolar, and bridges abutted at each end by hemisectioning of a periodontally damaged molar. With crowns and bridges, prospects for oral hygiene are determined by the following: the position of the crown margin, the contour of the crown in the marginal area, and the contour of the under-surface of the pontic. If optimum prospects for oral hygiene have been created by good coordination between the periodontist and the prosthodontist, the prognosis in the maintenance phase is considerably improved.     

Tooth loss and the condition of the prosthodontic appliances in a group of elderly home residents

The study assessed the number of missing teeth, the state of the existing prosthodontic appliances and the need for their replacement. Dental status and anamnesis were taken on a group of 120 elderly home residents by trained examiners. Prosthodontic appliances were evaluated according to the Karlsson's index for the crowns and bridges, and according to the modified Nevalainen et al. index for the evaluation of the complete dentures, as well as the need for prosthetic treatment. The most persistent teeth in both jaws were lower canines, while the most commonly missing teeth were lower first molars. On average, the crowns were older and in poorer condition than the bridges. Lower complete dentures had better stability but were also less retentive in comparison with the upper complete dentures. More than 82% of the subjects were in need of either fixed, removable or combined prosthodontic treatment. The high prevalence of needs for prosthodontic treatment pointed to the requirement for frequent dental check ups within elderly home residents in order to better identify and meet their dental needs.     

The use of crowns to modify abutment teeth of removable partial dentures 2. Clinical and laboratory procedures

Major modifications of abutment teeth can only be achieved by the use of restorations. Full crowns enable these modifications to be made in conjunction with ideal design and location of the components of removable partial dentures. Part 1 of this paper discussed these relevant components while in Part 2 the clinical and laboratory procedures are described.     

老年人可摘局部义齿修复对基牙的影响

目的:分析研究老年人可摘局部义齿修复后对基牙的影响,探讨其原因及预防措施。方法:对95例牙列缺失后的老年人行冷弯卡环固位式可摘局部义齿修复,记录和比较戴可摘局部义齿后基牙和非基牙的龋坏率和缺失率,用χ2检验分析其结果有无差异,并对影响基牙的原因进行分析。结果:戴用可摘局部义齿5a后,基牙的患龋率(17.38%)显著高于非基牙(7.10%);因牙折、牙周病松动及龋坏无法保留而拔除的基牙缺失率(27.01%)也显著高于非基牙(7.79%)(P<0.01)。结论:冷弯卡环固位可摘局部义齿修复后在一定程度上可增加老年人基牙的患龋率和缺失率。     

Single-tooth implants and their role in preserving remaining teeth: a 10-year survival study

The use of teeth as abutments for fixed and removable partial dentures can result in biologically destructive consequences. Teeth adjacent to edentulous spaces should exhibit improved prognoses if restorative trauma is to be avoided or minimized. Implants offer a method of tooth replacement without relying upon the surrounding dentition for support. This investigation evaluates implant survival and prosthetic complications of implants that replaced single missing teeth and were placed in clinical practice during a 10-year period. It further examines preoperative status and survival of teeth adjacent to these implant restorations during the same 10-year time span. Ninety-nine patients treated with 116 implants and 112 single-tooth implant prostheses in a prosthodontic practice were examined between 1988 and 1998. The purpose of this study was to evaluate the role of implants in preventing the use of intact teeth for initial support of prostheses and in avoiding the use of additional teeth as abutments upon the replacement of existing restorations. Three implants failed over a 10-year period, for a survival rate of 97.4%. Complications included the loss of 2 implant crowns, screw loosening, broken screws, cement washout, margin exposure, and porcelain fracture. Of 196 teeth adjacent to edentulous spaces, 156 (79.6%) were intact or minimally restored. Only 3 of these teeth were restored as part of initial prosthodontic therapy. Over the ensuing 10 years, only 1 tooth required a replacement restoration, and 1 tooth was extracted. Results of this patient evaluation demonstrated that implant survival over a 10-year period was favorable, with minimal prosthetic complications. Furthermore, teeth adjacent to single-tooth implants exhibited an extremely low complication rate. This report indicates that implants can be effective in preserving intact teeth in patients undergoing initial prosthodontic therapy and in preventing the use of additional teeth as abutments in patients whose existing prostheses must be replaced.