长正中《牙合》型下颌全口义齿近中移位量的初步研究

目的 探讨无牙颌患者戴用长正中<牙合>型全口义齿3个月后下颌义齿的近中移位量能否满足患者长正中量的自然要求,从而检验长正中<牙合>型全口义齿的设计理论. 方法 为10例无牙颌患者制作长正中<牙合>型、线性<牙合>型和解剖<牙合>型3种全口义齿,采用哥特式弓描记装置测量无牙颌患者的长正中量,采用三维精密平移台测量3种<牙合>型下颌义齿的近中移位量.对比分析不同<牙合>型下颌义齿近中移位量的差异,并与患者长正中量进行对比. 结果 10例无牙颌患者的长正中量为(1.02±0.36)mm,3种<牙合>型下颌义齿的近中移位量分别为:长正中<牙合>型(1.016±0.348)mm,线性<牙合>型(1.092±0.448)mm,解剖<牙合>型(0.409±0.253)mm. 结论 长正中<牙合>型全口义齿能满足患者长正中量的自然要求,以及在患者正中关系位至肌力闭合道终点的位置之间无障碍的义齿设计要求.     

Dissertations 25 years after date 25. Dentures: a question of grinning and bearing it

'Dentures: A question of grinning and bearing it' is not just the title of a 25-year-old thesis, but it also reflects the content well. Dissatisfaction with complete dentures is not only determined by the quality of the dentures and the oral conditions, but also and just as much by the patient's capacity to adapt to and accept the dentures. In order to treat an edentulous patient adequately, an oral healthcare provider should pay special attention to these aspects. After 25 years of further scientific study, this conclusion is still true. The current care standard for edentulous patients with atrophy of the residual mandibular alveolar ridge is an overdenture supported by 2 implants. For edentulous patients with a solid residual mandibular alveolar ridge, conventional complete dentures are the first choice of treatment. Only in cases of obvious remaining complaints, should an implant-supported overdenture be considered.     

不同排牙方法对全口义齿修复影响的临床研究

目的 探讨不同的排牙方法对无牙颌患者满意度和全口义齿咀嚼效能的影响.方法 采用上颌排牙法、下颌排牙法和综合排牙法为10例无牙颌患者分别制作3副全口义齿.戴用3个月后,测试无牙颌患者对3种全口义齿的满意度,同时通过吸光度法测定咀嚼效率及咀嚼次数,比较三种排牙方法的全口义齿咀嚼效能的异同.结果 无牙颌患者在戴用3个月后对下颌排牙法和综合排牙法全口义齿的满意度均好于上颌排牙法义齿.本实验3组全口义齿中下颌排牙法和综合排牙法全口义齿的咀嚼次数和咀嚼效能无显著差异,但均好于上颌排牙法义齿.结论 下颌排牙法和综合排牙法的全口义齿排列的人工牙有利于无牙颌患者在咀嚼过程中稳定地使用义齿,提高咀嚼效能,而且无牙颌患者对下颌排牙法和综合排牙法的全口义齿也更满意.     

牙槽嵴条件对全口义齿修复影响的临床研究

探讨无牙颌牙槽嵴条件，特别是下颌牙槽嵴条件对全口义齿修复效果的影响。方法无牙颌患者６２人，条件好组３０人，条件差组３２人，测试上下总义齿和固位力，咀嚼效率，和第一月，第三月的全口义齿满意度。结果不同牙槽嵴条件两组间的固位力，咀嚼效率，和第一月，第三月的总满意度及各单项满意虽略有差别。     

On the role of number of fixtures, surgical technique and timing of loading

AIMS: The aims of this thesis were to analyze reduced number of implants supporting full arch fixed mandibular prostheses and fixed partial dentures (FPDs), non-submerged healing and early loading in the edentulous mandible. A further aim was to evaluate fit of Computer Numerical Controlled (CNC) milled I-Bridge frameworks. MATERIAL & METHODS: Paper I. One hundred and nineteen patients rehabilitated with full arch mandibular prostheses supported by four implants were evaluated after a mean follow-up of 4.4 years. Paper II. A total of 178 patients provided with FPDs supported by two (n=92) or three implants (n=122) of whom 123 were evaluated after a mean follow-up of 9.4 years. Paper III. Early and delayed loading of full arch mandibular prostheses were evaluated in 109 patients, 54 with delayed loading and 55 with early loading, with a mean follow-up of 3.6 years. Paper IV. Submerged and non-submerged implant placement for supporting fixed prostheses in the edentulous mandible were evaluated after five years in 29 patients. Paper V. The precision of fit of CNC-milled I-Bridge frameworks was evaluated using two different implant systems. RESULTS: Paper I. The five-year cumulative survival rate (CSR) for implants was 99.1% and for prostheses 100%. Mean bone loss from baseline to five-year follow-up was 0.5 mm. No indication could be found that the number of supporting implants influenced the prosthetic complications. Paper II. The five-year implant and prosthesis CSR was 97.7% for two-implant supported FPDs and 97.3% for three-implant supported FPDs. Mean bone loss at five years was 0.4 mm. Significantly more prosthetic and abutment screw loosening were seen in two-implant supported FPDs. Paper III. Five-year CSR for implants was 94.4% and 92.5% for prostheses in early loading, and 97.9% and 98.0% in the delayed loading group. More prostheses needed adjustment or replacement in the early group, but patients treated with early loading were more pleased with the treatment procedure. Paper IV. Five-year CSR survival rate was 99.4%. Three implants fractured in one patient. Mean bone loss at five years was 0.7 mm in submerged implants and 0.5 mm in non-submerged implants. Paper V. All frameworks demonstrated clinically acceptable fit with mean distortion values within 23 microm (x-axis), 26 microm (y), 4 microm (z- axis) and 34 microm (3-D) for all frameworks. Control frameworks displayed greater levels of distortion than frameworks produced in a strict test situation. CONCLUSION: A reduction of the number of supporting implants to four implants in full arch mandibular prostheses and two implants in three unit FPDs in partial edentulous jaws resulted in the same clinical outcome as when more implants are used. Non-submerged implant placement in the edentulous mandible was as predictable as submerged, but early loading of implant-supported mandibular prostheses incurred more prosthetic complications. Computer numerical controlled milled frameworks presented levels of precision of fit within limits considered to be clinically acceptable and superior to earlier published results on cast frameworks.     

Does the nature of the definitive impression material influence the outcome of (mandibular) complete dentures?

The effects of impression materials on the outcome of complete dentures are poorly understood. This double-blind cross-over randomized controlled trial investigated eleven adult edentulous patients. Each received a maxillary denture and three mandibular dentures (which differed only in the three materials used to record the definitive impressions). The three mandibular dentures were given in a random order. Patients' opinions of each denture were recorded using a Linear Analogue Scale. There was a statistically-significant difference between the outcome of the dentures constructed when zinc-oxide eugenol was used, this material being least favoured (p < 0.001). It would therefore appear that care should be exercised when selecting impression materials when constructing mandibular complete dentures.     

An investigation of factors influencing patients' satisfaction with new complete dentures using structural equation modelling

OBJECTIVE: To investigate possible relationships between patient and clinical factors and patient satisfaction with new complete dentures. METHODS: Patients attending King's College London Dental Institute, Guy's Hospital, London, for new complete dentures were recruited. Relevant history was recorded and the edentulous mouth and existing dentures, where present, were examined at the beginning of treatment. The edentulous mouth, the previous and new dentures were re-examined at the first post-insertion visit. Three months after this visit, patients were sent a postal questionnaire to assess patient satisfaction. Data were analysed using structural equation modelling techniques. RESULTS: 723 patients were recruited. Significant relationships were found between quality of complete dentures, quality of residual alveolar, adaptability factors and patients' satisfaction with complete dentures. CONCLUSIONS: Quality of the mandibular residual alveolar ridges, retention and stability of the mandibular dentures, accuracy of reproduction of retruded jaw relationship and patient adaptability were powerful determinants of patients' satisfaction with new complete dentures.     

Mandibular complete denture versus single‐implant overdenture: a systematic review of patient‐reported outcomes

The single‐implant mandibular overdenture (SIMO) has been proposed as an alternative for edentulous patients who are poorly adapted to their dentures due to low retention and stability of the conventional mandibular complete denture (CD). However, there is a lack of evidence regarding the effectiveness of SIMO, which can be measured by examining patient perception of treatment effects. The aim of this systematic review was to assess the comparative results of CD and SIMO treatments using patient‐reported outcome measures. A literature search was carried out in PubMed, Scopus and Cochrane Central databases. The search included studies published up to July 2017. The focus question was: ‘Do single‐implant mandibular overdentures improve patient‐reported outcomes compared to conventional complete dentures in edentulous patients?’ Eligible studies were randomised clinical trials (RCT) and prospective studies. After initial screening for eligibility and full‐text analysis, 11 studies were included for data extraction and quality assessment (five parallel‐group RCTs, two crossover RCTs and four prospective studies). All studies reported marked improvement in satisfaction with the dentures and quality of life measures after SIMO treatment, irrespective of variations in implant treatment protocols and retention systems. Methodological considerations revealed a lack of evidence from RCTs on the comparative effectiveness of the two treatment strategies. Hence, although available evidence suggests considerable improvement in patient‐reported outcomes following the insertion of a single implant to retain a mandibular denture, further well‐designed comparative studies between SIMO and CD are required to improve the level of evidence and to support the indication of SIMO treatment in routine practice.     

Kinesiographic study of mandibular movements during functional adaptation to complete dentures

After complete denture insertion, edentulous patients usually present transitory difficulties. This is one of the most critical stages of prosthetic treatment and it is strongly related to the prostheses acceptance. The aim of this study was to evaluate potential changes in the mandibular movement pattern related to insertion of the complete denture during the functional adaptation period. The kinesiograph instrument K6-I (Myotronics Research Inc., Seattle, WA) was used to evaluate eight edentulous patients that received conventional complete denture treatment. Recordings of opening and closure movement limits, movement velocity, postural rest position, chewing cycle and limits of eccentric movements were performed. Each patient was evaluated in four different stages: with the old dentures, immediately after insertion of the new dentures, and 30 days and 6 months after insertion of the dentures. The results showed that there were no remarkable changes in the mandibular motion patterns after insertion of the new dentures. It was suggested that the problems related to the process of utilization of new dentures are not strictly associated to the mandibular movement. Therefore, functional adaptation after denture insertion is not directly related to functional changes, but to the quality of the dentures and to individual features.     

Interrelationship between implant and orthognathic surgery for the rehabilitation of edentulous cleft palate patients: a case report

A 43-year-old woman with a unilateral cleft lip and palate, presenting a totally edentulous maxilla and mandible with marked maxillomandibular discrepancy, attended the Prosthodontics section of the Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo for treatment. She could not close her mouth and was dissatisfied with her complete dentures. Treatment planning comprised placement of six implants in the maxilla, four in the mandible followed by prostheses installation and orthognathic surgery. The mandibular full arch prosthesis guided the occlusion for orthognathic positioning of the maxilla. The maxillary complete prosthesis was designed to assist the orthognathic surgery with a provisional prosthesis (no metal framework), allowing reverse treatment planning. Maxillary and mandibular realignment was performed. Three months later, a relapse in the position of the maxilla was observed, which was offset with a new maxillary prosthesis. This isa complex interdisciplinary treatment and two-year follow-up is presented and discussed. It should be considered that this type of treatment could also be applied in non-cleft patients.     

Diagnostically restoring a reduced occlusal vertical dimension without permanently altering the existing dentures

The technique described provides the dentist with a means of diagnostically restoring the vertical dimension of occlusion for an edentulous patient, without permanently altering the dentures. This procedure is accomplished with a removable mandibular splint, which snaps over the mandibular denture. The procedure involves little clinical treatment time. The maxillary denture may also be temporarily overlayed in a similar manner, but the procedure is generally not as esthetically acceptable. Since the mandibular alveolar bone resorbs much faster than that of the maxillae in most edentulous patients, the mandibular denture usually is responsible for most of the loss of occlusal vertical dimension. The mandibular denture is therefore most frequently indicated for alteration to restore lost occlusal vertical dimension. Medicolegal implications, as well as practical considerations, suggest that the patient's present dentures should not be permanently altered before new dentures are found to be satisfactory.     

Vertical dimension measurements

Changes in the vertical dimension of mandibular rest position for 50 subjects wearing complete dentures were measured on cephalometric radiographs between lead markers attached to the face and between skeletal landmarks. Measurements between the landmarks were compared on radiographs made without (edentulous) and with (edentoprosthetic) the dentures in the mouth. The findings support the following statements. The facial structures tended to mask the positional changes of the mandible. The rest position of the edentulous mandible tended to vary within the time frame of the cephalometric examination. The range of measurements of the skeletal rest position appeared greater with greater denture age and experience of the subjects. The rest position of the edentoprosthetic mandible (with dentures in the mouth) was more frequently constant when measured skeletally than when measured facially and more frequently constant than the edentulous mandibular rest position. The edentulous mandibular rest position of most subjects was increased upon insertion of dentures. The rest position was decreased for the remainder of the subjects. As a group, those subjects whose mandibular rest position decreased (up-shifted) with insertion of dentures had older dentures and more years of denture-wearing experience than subjects whose mandibular rest position increased (down-shifted) with insertion of dentures. The edentulous mandibular rest position does not seem particularly suitable for determination of the vertical dimension of occlusion and appears somewhat less suitable when facial measurements are used.     

The effectiveness of palate-less versus complete palatal coverage dentures (a pilot study)

The aim of this pilot study was to evaluate the effectiveness of palate-less dentures as a substitute for conventional complete palatal coverage. Ten edentulous patients who had recently received maxillary and mandibular complete dentures were included in the study. The patients' maxillary conventional dentures were duplicated to construct 'U' shape palate-less dentures. A strain gauge biting fork was used to compare the maximum biting force and chewing tests using almond were performed. They failed to show significant differences. Eight patients were more comfortable with the palate-less dentures than the complete palatal coverage. It was concluded that Palate-less dentures could be as effective as dentures with complete palatal coverage.     

One-Year Prospective Evaluation of the Early Loading of Unsplinted Conical Brånemark Fixtures with Mandibular Overdentures Immediately following Surgery

Background: Prospective evaluation of the early loading of unsplinted Branemark implants with mandibular over‐dentures opposing conventional dentures is not evident in the implant‐related literature. Purpose: To clinically evaluate progressive and early loading of 20 unsplinted conical Brånemark implants in edentulous mandibles with overdentures. Materials and Methods: Ten edentulous patients all had two conical Brånemark implants placed in the anterior mandible with mandatory primary stability with bicortical anchorage. Ball abutment connection was performed simultaneously. Previously constructed conventional mandibular dentures were temporarily relined with tissue conditioner postoperatively and worn with moderation for the first 2 weeks to allow progressive loading. Early loading of the implants followed after 2 weeks, with inclusion of the respective matrices in the mandibular dentures, using a definitive reline procedure. Results: All patients successfully functioned with their mandibular implant overdentures from 2 to 52 weeks postoperatively. Mean marginal bone loss was within established criteria for success:0.22 mm (SD = 0.48 mm) mesially and 0.30 mm (SD = 0.39 mm) distally on the conical implants. Mobility tests using the Periotest instrument became more negative, although not at statistically significant levels. Difficulties in the management of the peri‐implant mucosa between surgery and loading at 2 weeks were observed in 40% of the patients. Conclusions: These preliminary 1‐year results show that successful early loading of unsplinted conical Brånemark implants with mandibular overdentures is possible.     

Effect of implant-supported or retained dentures on masticatory performance: a systematic review

STATEMENT OF PROBLEM: While subjective patient-based measures have been increasingly recognized as critical outcomes for prosthodontic treatment, there continues to be a need to validate for patients what changes in masticatory function can be expected with the provision of new implant-supported or retained dentures. PURPOSE: The purpose of this review was to evaluate the critical factors impacting change in masticatory performance following the provision of new implant-supported or retained dentures. MATERIAL AND METHODS: Information retrieval followed a systematic approach using PubMed and the Cochrane Library. English articles published from 1966 to June 2007, in which the masticatory performance of subjects with implant-supported or retained dentures was assessed by objective methods and compared to performance with conventional dentures, were included. Ratings of the evidence provided in each article followed United States Agency for Healthcare Research and Quality recommendations. RESULTS: From 281 articles identified, 18 peer-reviewed articles met prespecified criteria for inclusion. Specific outcomes of significance identified by these articles rated as level II are: (1) fixed implant-supported partial dentures do not provide significant improvement in masticatory performance compared to conventional removable partial dentures for Kennedy Class I and II partially edentulous mandibles; (2) the combination of a mandibular implant-supported or retained overdenture (IOD) and maxillary conventional complete denture (CD) provides significant improvement in masticatory performance compared to CDs in both the mandible and maxilla for a limited population having persistent functional problems with an existing mandibular CD due to severely resorbed mandible; and (3) the type of implant and attachment system for mandibular IODs has a limited impact. Specific outcomes of significance identified by articles rated as having a moderate level of evidence (level III) are: (1) mandibular fixed implant-supported complete dentures provide significant improvement in masticatory performance compared to mandibular CDs in subjects dissatisfied with their CDs; and (2) implant-supported mandibular resection dentures have an advantage over conventional dentures in masticatory performance on the defect side of the mouth. CONCLUSIONS: Objective benefits in masticatory performance of implant-supported or retained dentures compared to conventional dentures are limited to a mandibular IOD in edentulous patients with a resorbed mandible and/or difficulty adapting to CDs.     

ELECTROMYOGRAPHIC EVALUATION OF MASTICATION AND SWALLOWING IN ELDERLY INDIVIDUALS WITH MANDIBULAR FIXED IMPLANTSUPPORTED PROSTHESES

This study evaluated the effect of implant-supported oral rehabilitation in the mandible on the electromyographic activity during mastication and swallowing in edentulous elderly individuals. Fifteen patients aged more than 60 years were evaluated, being 10 females and 5 males. All patients were edentulous, wore removable complete dentures on both dental arches, and had the mandibular dentures replaced by implant-supported prostheses. All patients were submitted to electromyographic evaluation of the masseter, superior orbicularis oris muscles, and the submental muscles, before surgery and 3, 6 and 18 months postoperatively, using foods of different textures. The results obtained at the different periods were analyzed statistically by Kruskal-Wallis non-parametric test. Statistical analysis showed that only the masseter muscle had a significant loss in electromyographic activity (p<0.001), with a tendency of similar response for the submental muscles. Moreover, there was an increase in the activity of the orbicularis oris muscle during rubber chewing after treatment, yet without statistically significant difference. Mandibular fixed implant-supported prostheses in elderly individuals revealed a decrease in electromyographic amplitude for the masseter muscles during swallowing, which may indicate adaptation to new conditions of stability provided by fixation of the complete denture in the mandibular arch.     

Surgical and prosthetic treatment of the atrophic mandible

Two vestibuloplasty methods and a muscle-formed method for improving the retention and stability of complete mandibular dentures were compared in 19 edentulous patients with advanced mandibular bone resorption. The resorptive changes in the alveolar crest and any relapse in the extended vestibule after surgery were monitored for 2 yr. Simultaneous production of the first new complete dentures, to which the labial plate is added during the surgical procedure, and firm circummandibular fixation during primary healing will guarantee the best surgical and prosthetic results. This order of treatment also eliminates unnecessary surgical procedures. A muscle-formed method for extending the baseplate of a complete mandibular denture was found to be a useful alternative for patients with highly advanced mandibular bone resorption.     

The mandibular complete overdenture

Mandibular complete overdenture treatment has been available for decades, but its use was limited when the treatment relied on retained teeth as overdenture abutments. This treatment, however, is currently experiencing more popularity than ever before. In fact, dentistry may be experiencing a philosophical shift, in which mandibular implant overdenture treatment may become the new standard of care for the treatment of the edentulous mandible. Practitioners are looking for simplified treatments that can provide cost-effective alternatives to more complex implant prosthodontic procedures. Implant overdentures provide a strong return for the investment in treatment time and expense and are a treatment suited to the lower socioeconomic status of many edentulous patients. The clinical outcome of this treatment is significantly better than that achieved with conventional mandibular dentures, especially when patients are experiencing technical problems because of compromised prosthesis retention or stability.     

Similarities in resorption patterns of maxillary and mandibular ridges

The differences in the posterior arch widths between opposing maxillae and mandibles were studied in 100 edentulous denture-wearing patients. Panoramic radiographs of 67 of these patients were used to assess the percentage of mandibular height reduction from that considered present before extractions. Comparisons between posterior maxillary and mandibular arch widths, reductions in mandibular height, and edentulous age accompanied by denture wearing were made. The following conclusions emerged: 1. The mandible does not progressively widen as its opposing maxillae becomes narrower, nor does a progressive incremental increase occur in posterior maxillomandibular width relations with increased resorption or resorptive age. 2. The arch width of the mandible exceeds the arch width of the maxillae in the molar region by an average of 6 to 7 mm after sufficient resorption establisheds a definitive alveolar crest. This difference remains the same regardless of the amount of resorption or resorptive age. 3. The progressive and irreversible mandibular alveolar resorption rate is greatest in the earlier stages of edentulism and slows with loss of bone, longevity of edentulism, and attendant wearing of dentures.