Planning oral rehabilitation: case-based computer assisted learning in clinical dentistry

The partially edentulous adult offers a unique and problem-rich resource as a basis for a case-based learning scenario in clinical dentistry in the field of planning oral rehabilitation. However, there is little resource material available to help students negotiate the territory between diagnosis and treatment options of discrete conditions and treatment sequencing once decisions have been made. To address the educational void surrounding the teaching and learning of oral rehabilitation strategies, the authors have developed a CD-ROM 'Interactive Learning in Dentistry: Decision making in the oral rehabilitation of the partially edentulous adult'. The disc emphasises the distinction between 'doing' and 'planning to do' in the decision-making process. After using the disc the students should be able to apply a generic framework to formulate a custom oral rehabilitation plan for their own patient. The disc was evaluated by final-year students from the Faculty of Dentistry, University of Sydney. Response to the program was essentially positive and comments from students have impacted on further development.

Strategies for complete denture success: beyond technical excellence

Many patients are quite satisfied with dentures that are extremely poor, while other patients are dissatisfied with dentures that are technically excellent. Overall, some 25% of patients are likely to be dissatisfied with their artificial teeth. This article addresses the aspects of denture success not covered by technical considerations. The strategies are based on the principles of good communication and involve an understanding and respect for patients' motivations in wearing dentures. The strategies include help in the development of neuromuscular control and in training regarding mastication. Most importantly, they emphasize patient involvement in the development of the denture. Patients must be made aware of their responsibilities in achieving a satisfactory outcome in the complex patient/denture relationship.

Titanium for removable partial dentures (III): 2-year clinical follow-up in an undergraduate programme

This study examined the success of titanium (Ti) removable partial dentures (RPDs) compared with that of cobalt-chromium (Co-Cr) RPDs using a randomized controlled clinical trial. Thirty-eight RPD patients were provided with either Co-Cr (20 patients) or Ti (18 patients) RPDs. The total numbers of dentures was 31 (13 maxillary, 18 mandibular) for Co-Cr and 23 (11 maxillary, 12 mandibular) for Ti. Patients were reviewed for 24 months following denture issue. After the initial 12 months, 20 clinical problems were recorded and became the criteria for subsequent assessment. Incidence of failure was analysed using both Fisher's exact test and the chi square test at a significance level of P<0.05. Fracture of retainers in both metals occurred only in the first 12 months. Some failure types presented at significantly higher levels in the first 12 months but there were no significant differences between the two in all the criteria examined between the 12- and the 24-month reviews. Although differences existed in failure types between Co-Cr and Ti RPDs during the early review stages, the overall success rate of Ti RPDs was comparable with that of Co-Cr RPDs after 24 months. The higher incidence of failures in Ti RPDs prior to the 12-month review suggests the importance of taking its lower rigidity into account when designing RPDs.

Maxillary changes under complete dentures opposing mandibular implant-supported fixed prostheses

PURPOSE

The aim of this study was to determine whether a condition similar to Combination Syndrome occurs in patients rehabilitated with a maxillary complete denture opposing a mandibular implant-supported fixed prosthesis.

MATERIALS AND METHODS

Standardized clinical procedures measured fit, occlusal integrity, and bone loss in the anterior maxilla in 11 edentulous subjects meeting these requirements, from the patient pool of the Implant Centre, United Dental Hospital, Sydney.

RESULTS

A mean annual loss of 0.17 mm in the anterior maxillary ridge height was not statistically significant (P > 0.05). However, increased pressure in the anterior maxillary ridge during occlusion and loss of posterior occlusal contacts in retruded position were noted on one or both sides in all subjects.

CONCLUSION

Loss of posterior occlusion could not be related to anterior maxillary bone loss. However, to maintain the integrity of the prostheses and their supporting structures, it is important to schedule periodic recall appointments for review of the occlusion.

Evaluation of a computer-aided learning program in removable partial denture framework designing

Assessment of a computer-assisted learning (CAL) program dealing with designing removable partial dentures was performed as both formative and summative evaluation. Formative evaluation was obtained through open-ended questions in a written questionnaire administered to 60 junior students from two Australian Dental Schools and through observation of four groups of these students as they worked through the program. Formative evaluation, fundamental to completion of the program, led to several changes and additions. Observation of the students using the program during its final stages of development was one of the most informative and helpful parts of the evaluation. It allowed nuances of expression and body language to be noted that would not have been apparent in written or numerical data. Summative evaluation was obtained through structured questions in the questionnaire and through a post-CAL test under examination conditions. Summative assessment showed that students could attain a desired standard of knowledge if a lecture series was replaced by the CAL program; that the program was user-friendly, even for students with little or no computer experience; and that most students considered it to be a useful learning resource. More than half the students were concerned about using CAL to replace human instruction. It is significant that students were particularly impressed by aspects of the program that could not be duplicated by a book; the interactive nature of the learning process and the ability to rotate the diagnostic casts. This highlights the need for CAL programs to use the full potential of computer capability, rather than merely replicate a textbook on a screen.

An interactive multimedia solution to learning removable partial denture design

Surveys of the dental profession and dental laboratories show that up to 60% of cases received by laboratories have little or no input from dentists into the design of their patients' removable partial dentures (RPD). Thus, there is a clear mandate for dental schools to teach RPD design in new ways that will give their students confidence and allow their graduates to approach the task readily and easily. This computer-aided learning program addresses that need. In designing it, we have exploited the unique properties of computers as a learning tool. The program uses Quicktime VR to simulate a three-dimensional perspective of diagnostic casts. It is also possible to incorporate animated diagrams to illustrate various points. Control of timed answers promotes the use of inquiry-based learning and allows the program to be interactive and completely problem-oriented. Students can practice at their own pace, on a variety of virtual cases, and thus learn the craft behind the art of designing RPDs. With this foundation, discussions with experts in the field regarding the patients they treat in senior years and as graduates can be conducted at a higher and more productive level. Student evaluation so far has been very encouraging.

Survey lines revisited: finding nonundercut surfaces for retainers that approach from the occlusal surface

This study investigated survey lines on abutments in the partially edentulous mouth. Various methods that were used to determine the path of insertion had little impact on the position of survey lines except on tooth surfaces with minimal undercuts. Typical survey lines are described and according to the survey lines, few tooth surfaces could accommodate the rigid portion of an occlusally approaching retainer and permit it to be positioned on a nonundercut tooth surface. Although some degree of enameloplasty to improve the situation on some tooth surfaces is possible, the degree to which this can be done is limited by the thickness of the enamel and considerations of tooth conservation.

Combination syndrome in relation to osseointegrated implant-supported overdentures: a survey

Thirteen patients who had worn a maxillary conventional denture and mandibular osseointegrated implant-supported overdenture for at least 3 years were evaluated for subjective assessment of fit of the maxillary denture, occlusal integrity, and the status of the anterior maxillary residual ridge. The findings of this study support the view that this combination of prostheses can result in perceived loosening of the maxillary denture, loss of posterior occlusion, increased anterior occlusal pressure, and anterior maxillary bone loss, similar to the effects seen in Combination Syndrome. It is therefore important to ensure that where an implant-supported mandibular overdenture is planned for the edentulous patient, some form of stabilisation of the maxillary arch is also considered.

Complete denture problem solving: a survey

An investigation was carried out into the problems experienced by 114 referred patients with complete dentures who were considered to be difficult or to have difficult prosthodontic problems. The commonest problems were those of pain and lack of retention, due mainly to occlusal discrepancies and excessive VDO. Treatment was carried out on an individual basis with a large proportion of dentures being remade. However, a small number was satisfied by counselling alone without procedural treatment. A diagnostic denture technique was used for particularly difficult cases. This technique showed that, in two cases, technical prosthodontic inadequacies could definitively be excluded as the problem. The overall success rate for treatment was 80 per cent. Further studies on a larger patient sample are needed so that specific problems can be linked to cause and outcome in a meaningful manner.

Hard-copy provisional appliances in the rehabilitation of the edentulous patient

A technique is described whereby a diagnostic appliance simulating an implant-supported fixed prosthesis for the edentulous patient can be made quickly and relatively inexpensively. Such an appliance gives the patient an understanding of the physical limitations of various modalities of prosthodontic restoration. It is a tool that permits both the patient and the dentist to assess functional, esthetic, and phonetic criteria in the realistic setting of everyday usage. Important decisions regarding future treatment can thus be finalized before a huge financial commitment is made. It is a highly cost-effective technique, both financially and emotionally.

Interactive computer teaching/learning in the dental curriculum: partial denture design

Interactive multimedia is an emerging industry with a broad domain. It operates from a base of computer technology to enable the production, distribution and sharing of ideas. The use of multimedia in the educational setting is in keeping with the concept of learning, rather than teaching and, with this in mind, a pilot program in interactive computer learning has been developed which is geared specifically to the requirements of junior students. The design sequence and philosophy used in this program follow the teaching at Sydney University Dental School. Its purpose is to facilitate students in mastering the technical aspects of denture framework design, leading them through a set sequence of steps from saddle identification to finish. Future plans, using more sophisticated equipment, are to develop more advanced programs for senior (fourth year) students, including applications for treatment planning and also the rudiments of osseointegrated implant work.

Changes caused by processing complete mandibular dentures

Qualitative and quantitative comparisons were made before and after complete mandibular dentures were processed. Linear measurements indicated shrinkage in all dimensions, and the greatest shrinkage occurred in an anteroposterior direction along the lingual flanges. Differences in shrinkage across the various points measured suggest that the denture material twists during curing, and the final qualitative changes appear as pressure areas in the distolingual and anterolabial regions.

Removable partial denture design: importance of clinical variables

A study was conducted to ascertain the influence of clinical variables on removable partial denture design. Dentures were first designed using only the information usually available to technicians, namely, surveyed, articulated study casts. These designs were then modified using information available to the dentist, that is, clinical variables. Of the 208 dentures analysed, 80 (39%) needed modification to 171 components because of patient-related variables. This high number of modifications reinforces the position that removable partial denture design should be instigated and guided by the dentist.

Imaging for predictable maxillary implants

Whereas other radiographs may be adequate for assessment of mandibular anterior implant sites, the use of computerised tomography is recommended for evaluating potential implant sites in the maxillae. A complete denture replica with appropriate radiopaque markers aids in the assessment. Hounsfield densitometric measurements provide additional information on the quality of available bone.

Teaching complete dentures

Success in wearing complete denture depends, in order of importance, on motivation, neuromuscular control and technical considerations. To address the two aspects of motivation and neuromuscular control, fourth year students at Sydney University are taught a protocol which encompasses duplication of the patient's existing denture and modification of this duplicate to satisfy the patient's needs and wants. This modified duplicate denture acts as a diagnostic prototype which is used as a guide during construction of the new denture.

Processing changes in maxillary complete dentures

A technique that allows for comparison of undercuts palatal thickness, and double curing has been described for measurement of curing changes in acrylic resin dentures. The technique involves a precision cast and denture positioner in front of the x-ray tube and the transfer of a lead foil strip from cast to denture. Radiographs made of this strip are projected at X20 magnification, and subsequent tracings are measured and superimposed to note shrinkage and contour changes.