Effect of groove placement on the retention/resistance of resin-bonded retainers for maxillary and mandibular second molars

STATEMENT OF PROBLEM

Lack of retention/resistance form in the clinical preparation of teeth for resin-bonded retainers may lead to clinical failure.

PURPOSE

This study investigated the effect of proximal grooves on the retention/resistance of cast resin-bonded retainers for maxillary and mandibular second molar teeth.

MATERIAL AND METHODS

Two ivorine teeth (a maxillary and a mandibular second molar) were prepared for resin-bonded retainers. Twenty metal replicas of the prepared teeth were made (10 for each tooth morphotype). Resin-bonded retainers 0.5 mm thick were made for the 40 replicas and luted with Panavia EX cement. Forces for dislodgment of the retainers were applied along the long axes of the teeth. Forces recorded at the time of dislodgment were analyzed with 2-way analysis of variance and the post hoc Scheffé test.

RESULTS

Grooves resulted in substantial increases in debonding forces for maxillary molars (P<.001). The effect of grooves on mandibular second molars was not significant (P=.13).

CONCLUSION

Grooves placed in tooth preparations of maxillary molar teeth for resin-bonded retainers had a significant effect on retention/resistance. The effect of grooves on mandibular second molars was less pronounced.

Caries incidence following restoration of shortened lower dental arches in a randomized controlled trial

CONTEXT

Removable partial dentures used to restore the shortened lower dental arch may adversely affect the remaining natural teeth and are associated with a low prevalence of use.

OBJECTIVE

To report the findings for caries incidence 2 years after restoration of lower shortened arches with bilateral cantilever resin-bonded bridges (RBBs) and conventional partial dentures (RPDs).

DESIGN

Randomised controlled trial.

SETTING

Secondary care

PATIENTS

25 male and 35 female subjects of median age 67 years. were randomly allocated to 'bridge' and 'denture' treatment groups of 30 patients each matched for age and sex. Caries incidence was recorded during dental examinations 3 months, 1 and 2 years after insertion of new lower prostheses.

INTERVENTIONS

Cantilever RBBs and conventional RPDs with cast metal frameworks.

RESULTS

There was a highly significant difference in the frequency of new caries lesions, 11 and 51 in the bridge and denture groups respectively (P < 0.01). 20 out of 27 bridge patients and 9 of 23 denture patients had no caries experience. Multivariate modeling identified treatment group as the only significant predictor of caries occurrence.

CONCLUSIONS

Two years after restoration of lower shortened arches for an elderly sample of patients, there was a significantly greater incidence of new and recurrent caries lesions in subjects restored with RPDs compared with cantilever RBBs.

The use of group participation and an enquiry-based study guide with computer assisted learning

The aim of this investigation was to explore the use of group participation and an enquiry-based study guide to enhance the learning experience when using a computer assisted learning (CAL) program.

MATERIALS AND METHODS

Forty-eight students were asked to complete a CAL program on resin bonded bridges in groups of 2-4 with an enquiry-based study guide. An evaluation questionnaire of the learning experience was included with the study guide with paired positive and negative questions and open-ended questions for students to complete and return. The responses were collated and the nature of the comments qualitatively analysed.

RESULTS

Thirty-two questionnaires were returned. There were almost three times the numbers of positive to negative responses relating to the usefulness of the enquiry based study guide, group participation and the CAL program. The majority of these positive responses related to the usefulness of the study guide and group participation in highlighting and guiding learning and creating opportunities for discussion, problem solving and peer teaching. A small number of negative responses cited the target-orientated nature of the study guide and the longer time needed for group work, due to the varying learning abilities of the participants and the need for discussion.

CONCLUSION

The use of group participation and an enquiry-based study guide was reported to enhance the learning experience of CAL.

The resin retained natural tooth pontic: a transitional esthetic solution

This case report presents an alternative treatment option for the premature loss of a maxillary anterior tooth due to severe periodontitis. A natural tooth pontic acid-etch prosthesis was fabricated using the patient's clinical crown from the extracted tooth. This measure proved to be a very adequate, esthetic treatment solution before a permanent restorative plan could be developed for the patient's long term dental needs.

[Repair and revision 5. Failures and repair of resin-bonded bridges]

This article describes a number of aspects dealing with debonding, recementation and patients' satisfaction in the treatment with resin-bonded bridges. Experiences from two large clinical trials are reported. It was found that rebonded bridges were less successful than the originally bonded bridges. However, since the functional survival rate was significantly higher than the original survival rate, together with the relative low cost of recementation, it is advised to recement debonded bridges. After multiple debonding recementation can be questioned. Multiple debonding is considered to point to an inadequate indication of this type of fixed prostheses. Debonding of bridges did not alter the patients' satisfaction. This might be caused by the fact that the possibility of failure was explained to the patient when informed consent was obtained.

In vitro repair of three-unit fiber-reinforced composite FPDs

PURPOSE

Clinical damage, such as the fracture or abrasion of composite veneers, may cause the loss of a fixed partial denture (FPD). Intraoral methods may help in repairing and therefore lengthening the life span of the restoration. The aim of this in vitro study was to evaluate an intraoral method of repairing fractured FPDs made of two different fiber-reinforced composite framework systems.

MATERIALS AND METHODS

Shear bond strengths of a composite between two different fiber-reinforced composite frameworks were determined after five different mechanical surface treatments. A silicate-silane coating intraoral air-abrading system provided the most reliable bond strength values and was therefore used for treatment for the following veneer repair. The repair of 24 three-unit posterior FPDs was performed using a restorative composite resin. All FPDs were examined after simulating clinical service using thermocycling and mechanical loading. Fracture forces were determined for original FPDs and for FPDs after simulated intraoral repair.

RESULTS

The fracture strength of all original FPDs was about 900 N. After repair, a maximum decrease in strength of about 15% was determined. FPDs that were extremely damaged by cutting the framework showed the lowest results, with values of about 450 N.

CONCLUSION

The repair of the fractured veneer of fiber-reinforced composite FPDs provided good results and therefore may lengthen the life span of damaged FPDs. The repair of the fractured frameworks showed good results but can only be recommended for limited temporary use.

Buonocore memorial lecture. Adhesive dentistry applied to the treatment of traumatic dental injuries

Dental adhesive techniques have led to a significant simplification of the immediate and definitive treatment of traumatic dental injuries. Composite restoration of fractured teeth, bonding of tooth fragments, the use of laminate veneers or porcelain onlays and resin retained bridges are some of the ways adhesive techniques are used to treat fractured teeth. Furthermore, splinting of luxated teeth almost entirely relies on the combination of adhesion and a flexible resin which simulates the mobility of a normal periodontal ligament during the healing period. The internal strengthening of immature root-filled teeth with composite using an adhesive technique may possibly prevent late root fractures caused by weakening of the tooth structure resulting from endodontic procedures. Finally, the adhesive principle using a retro-seal with composite after apicoectomy significantly increases the healing rate and healing mode.

A simple method for single anterior tooth replacement

PURPOSE

This article reports a case in which a recently extracted tooth was used as a natural tooth pontic bonded to the teeth on either side of the missing tooth using a Ribbond ribbon.

MATERIALS AND METHODS

A bondable, reinforcing polyethylene ribbon was used to bond a natural tooth pontic to adjacent teeth.

RESULTS

Acceptable esthetics were obtained and the result was satisfactory for the patient.

CONCLUSION

After one year of clinical use, direct construction of a single-tooth replacement using the natural tooth pontic still provided satisfactory esthetics and function. The technology which makes this adhesive restoration possible is the development of a high strength, high molecular weight, biocompatible polyethylene fiber. This easily handled material must be evaluated in long-term clinical studies.

Effects of resistance form on attachment strength of resin-retained castings

This study evaluated the effects of tooth preparation design on resistance to dislodgment of a resin-bonded fixed partial denture (RBFPD). The variations of tooth preparation tested included axial coverage, retentive grooves, and an occlusal rest. Patterns of the tooth preparation designs were prepared and cast in a base metal alloy. Retainer patterns were waxed to refractory casts of metal dies, cast, finished and then bonded to the dies. The complete assemblies were loaded to failure on an Instron mechanical testing machine, and analysis indicated that retainers with occlusal rests were the most resistant. Grooves provided no statistically significant increase in resistance to failure of the cement. Increased axial coverage did not increase resistance to dislodgment. Successful fixed partial dentures (FPDs) depend on cast retainers to resist displacement of the restoration during function. Introduction of resin-bonded restorations opened the possibility of FPDs with minimal reduction of abutments. Specific questions concerning long term success and tooth preparation designs were prominent concerns. The influence of resistance form on overall stability of a restoration was also of particular interest. Buonocore established the foundation for retention of composite resins to acid-pitted enamel. Rochette used this technology to bond perforated cast metal splints to periodontally compromised teeth. A mechanical interlock was created as composite resin engaged these perforations and sustained the cast splint to acid-etched enamel. Howe adapted this design for replacement of anterior teeth by adding porcelain to a metal ceramic framework and then bonding the framework to abutments without tooth preparations. The advantages of these procedures were their conservative nature, esthetics, and ease of rebonding after dislodgment. Livaditis and Thompson adapted the procedure proposed by Tanaka of corrosion-pitting the bonding surface of a base metal alloy. They increased the surface area to be bonded, eliminated the perforations to improve rigidity of the framework, and described tooth preparation modifications of the abutments. They suggested an occlusal rest, establishment of guide planes through axial reduction, and a proximal extension to the facial surface to resist lingual displacement. Simonson, et al., based their anterior tooth preparation design on the configuration suggested by Livaditis which included a slight chamfer finish line plus reduction of the lingual surface to provide a thicker metal framework. Barrack introduced an inlay type tooth preparation for the occlusal rest plus shallow vertical proximal grooves, and Meiers used grooves as an esthetic alternative to proximal extensions. Clinical studies and surveys have identified specific variables involved with success and failure, while in vitro studies have evaluated framework designs, bonding agents, and methods for pitting the metal surface. This study evaluated resistance of RBFPDs to dislodgment of different tooth preparation designs.

Ridge augmentation using mandibular tori

A 19-year-old female was referred by her dental practitioner for the restoration of missing maxillary lateral incisors and canines. Ridge augmentation was required. This was undertaken using mandibular tori as the sites for harvesting bone. The grafting was successful and the spaces were subsequently restored using resin-bonded bridgework. The case reports that mandibular tori provide a local and convenient source of bone for ridge augmentation procedures.

Management of median diastema

In mixed and early permanent dentitions, median diastema can be a major esthetic concern for patients and/or their parents. The space can be transient or created by developmental, pathological, or iatrogenic factors. Different treatment techniques have been proposed to manage the situation. This paper reviews the common causes of median diastema and presents four cases to illustrate a range of restorative and orthodontic options.

Case report: a glass fibre reinforced composite resin bonded fixed partial denture

A 55-year-old man was treated with a glass fibre reinforced composite resin bonded fixed partial denture with an increased bonding surface area. The abutments for replacing two maxillary premolars were not prepared and the bonding surface was expanded to the regions of undercut and the labial/buccal surface of the abutments. This was possible by tailoring the mechanical properties of the fibre reinforced composite frame of the resin-bonded fixed partial denture. Two and half years follow-up demonstrated good clinical success for the restoration. This experience encourages development of non-invasive prosthodontic treatment options for transitional fixed partial denture restorations.

Chairside prefabricated fiber-reinforced resin composite fixed partial dentures

The introduction of pre-impregnated fiber-reinforced resin composites has provided the dental profession with the opportunity to fabricate and deliver adhesive, esthetic, and metal-free tooth replacements. Utilizing this technology, a prefabricated fiber-reinforced resin composite fixed partial denture prototype that allows rapid, cost-effective, and noninvasive fixed tooth replacement for single anterior teeth has been developed. Ideal situations for this type of service include: a fixed replacement following tooth loss from trauma; a fixed tooth replacement in medically compromised patients who cannot sit for extended periods of time or have local anesthesia; periodontally compromised abutments; a fixed space maintainer following orthodontic movement; and a fixed provisional during the post implant healing phase prior to loading. This article describes the framework construction and placement protocol for the prefabricated fiber-reinforced resin composite fixed partial denture.

The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment

Orthodontic treatment for patients with uni- or bilateral congenitally missing lateral incisors is a challenge to effective treatment planning. The two major alternatives, orthodontic space closure or space opening for prosthetic replacements, can both compromise aesthetics, periodontal health, and function. The aim of this retrospective study was to examine treated patients who had congenitally missing lateral incisors and to compare their opinion of the aesthetic result with the dentists' opinions of occlusal function and periodontal health. In this sample, 50 patients were identified. Thirty had been treated with orthodontic space closure, and 20 by space opening and a prosthesis (porcelain bonded to gold and resin bonded bridges). The patient's opinion of the aesthetic result was evaluated using the Eastman Esthetic Index questionnaire and during a structured interview. The functional status, dental contact patterns, periodontal condition, and quality of the prosthetic replacement was evaluated. In general, subjects treated with orthodontic space closure were more satisfied with the appearance of their teeth than those who had a prosthesis. No significant differences in the prevalence of signs and symptoms of temporomandibular dysfunction (TMD) were found. However, patients with prosthetic replacements had impaired periodontal health with accumulation of plaque and gingivitis. The conclusion of this study is that orthodontic space closure produces results that are well accepted by patients, does not impair temporomandibular joint (TMJ) function, and encourages periodontal health in comparison with prosthetic replacements.

Resin-bonded fixed partial dentures and splints in periodontally compromised patients: a 10-year follow-up

In the present study, 139 periodontally compromised patients received a complete periodontal treatment; in 104 cases this was followed by orthodontic treatment. At the end of the entire therapy, a total of 150 Maryland restorations (69 resin-bonded fixed partial dentures and 81 resin-bonded splints) was placed and then followed for a period of up to 10 years (mean 6.7 y). Thirteen fixed partial dentures and 16 splints failed during the observation period; the 10-year cumulative survival rate from lifetable analysis was 76.2% (70.6% for fixed partial dentures and 80.7% for splints).

Decoronation: how, why, and when?

Decoronation is a surgical method for treating ankylosed incisors in children and adolescents. The crown and root filling are removed, leaving the root in situ to be resorbed and covered with a mucoperiosteal flap. Early loss of a permanent tooth leads to loss of alveolar bone, especially in buccopalatal width. Decoronation preserves not only the width of the ridge but also the vertical height.

Resin-bonded fixed partial dentures--a literature review with presentation of a novel approach

PURPOSE

Resin-bonded fixed partial dentures (RBFPD) have been in our profession for over 20 years. The aim of this work was to provide some background about their development and the factors that influence their clinical longevity.

MATERIALS AND METHODS

A recent literature search conducted using MEDLINE along with analysis of bibliographies of published papers revealed a considerable number of publications of RBFPDs since their first introduction in the mid-1970s. Critical analysis of these publications revealed some important and interesting key facts. These were divided into sections about developments in the treatment of the fit surface of the casting, bonding systems, and prosthesis design. A separate section about factors that affect the longevity of RBFPDs is included, along with a detailed description of preparation designs of an anterior and a posterior RBFPD.

RESULTS

The typical design of RBFPDs is characterized by a high degree of conservation of tooth structure of abutments compared with designs of conventional fixed prostheses. While the early RBFPDs were associated with a high frequency of premature failure--mostly because of debonding--developments in preparation design and bonding techniques as well as better understanding of the appropriate type of metal alloy to be used and the best preparation method for enhanced bonding have led to significant improvements in their long-term survival.

CONCLUSION

RBFPDs should be considered viable treatment options for those clinical situations that are best suited for their use. Preparation design, cement type, and casting alloy type as well as surface treatment are among the most important factors that influence longevity of RBFPDs.

Nutrient intake in partially dentate patients: the effect of prosthetic rehabilitation

OBJECTIVES

The objectives of this study were to investigate the impact of prosthetic rehabilitation of the shortened dental arch on the intake of nutrients, non-starch polysaccharide (NSP) fruits and vegetables (dietary fibre), and to compare dietary intakes between patients receiving bilateral resin-bonded bridges with patients receiving conventional partial dentures.

METHODS

As part of an ongoing randomised clinical trial to compare the effectiveness of bilateral resin bonded bridges with conventional partial dentures, the diets of 40 partially dentate patients were assessed prior to and at 3 and 12 months following treatment with bilateral resin-bonded bridge-work or a lower partial denture.

RESULTS

At baseline, three months post treatment and one year post treatment there were no significant differences in the intake of nutrients between groups. A significant increase in the percentage of energy from fat was observed in the patients fitted with a lower partial denture. Apart from this, prosthetic rehabilitation did not result in any other change in the intake of nutrients or in the amount of fruits and vegetables consumed. Levels of intake of NSP, fruits and vegetables were low in both groups of patients on all occasions measured.

CONCLUSIONS

Prosthetic rehabilitation of the severely shortened dental arch does not result in dietary improvements. Dietary advice that takes into account all the factors that influence food choice (such as taste, cost and cooking skills) needs to be considered in this at risk group.

Resin-bonded, glass fiber-reinforced composite fixed partial dentures: a clinical study

STATEMENT OF PROBLEM

Resin-bonded, glass fiber-reinforced composite fixed partial dentures (FPDs) have been under development for some time. There is a lack of data regarding the clinical usefulness of such prostheses.

PURPOSE

The clinical performance of 31 resin-bonded, glass fiber-reinforced composite fixed partial dentures was evaluated in a preliminary study.

MATERIAL AND METHODS

The prostheses were made to replace 1 to 3 missing maxillary or mandibular teeth in each of 31 patients. The prostheses had a framework made of continuous unidirectional E-glass fibers with multiphase polymer matrix and light-polymerized particulate composite resin veneering. The prostheses were examined after 6-month periods for up to 24 months (mean follow-up time was 14 months). Partial or total debonding of the prostheses or the framework fracture was considered a treatment failure.

RESULTS

Two prostheses debonded during the follow-up period; 1 debonding was related to improper occlusal adjustment and the other to unknown reasons. Kaplan-Meier survival probability at 24 months was 93%. No framework fractures were observed.

CONCLUSION

The results of this preliminary study suggest that the resin-bonded, glass fiber-reinforced FPDs may be an alternative for resin-bonded FPDs with a cast metal framework.

Retention of a posterior resin-bonded fixed partial denture with a modified design: an in vitro study

PURPOSE

The aim of this study was to test in vitro the resistance of a modified resin-bonded fixed partial denture (RBFPD) to detachment using a laboratory setup simulating load fatigue of mastication forces. The effect of varying the cement type was also investigated.

MATERIALS AND METHODS

Extracted teeth were used to prepare specimens each consisting of a premolar and a molar with a space equivalent to a molar in between. Five test groups were prepared (n = 7). Specimens in group 1 were prepared to receive conventional RBFPDs with proximal grooves, occlusal rests, and lingual wings. Specimens in groups 2 and 3 were prepared to receive modified RBFPDs with retentive-slot restorations. Specimens in group 4 were prepared to receive RBFPDs with retentive-slot restorations only, whereas specimens in group 5 were prepared similarly to the ones in groups 2 and 3 but with inlay preparations instead of the retentive slots. Castings were made and their fit surfaces microetched. In groups 1, 2, 4, and 5 castings were cemented with Cement-It, whereas castings of group 3 were cemented with Panavia 21. Slot cavities of groups 2, 3, and 4 were restored with a resin composite. Specimens were subjected to compressive load cycling for 230,000 cycles at 4 Hz under water. Castings were then separated from the abutments under tensile loading.

RESULTS

Mean separation forces were: group 1 = 361 N, group 2 = 525 N, group 3 = 562 N, group 4 = 449 N, and group 5 = 417 N. Groups 2 and 3 had significantly higher mean separation forces than groups 1 and 5. Separation of castings in groups 2 and 3 was associated with a higher frequency of cohesive fracture of the abutments than in group 1. Adhesive failure was uncommon among specimens of groups 2, 3, and 4.

CONCLUSION

The modified RBFPDs of groups 2 and 3 had better potential for retention. Increased resistance to dislodgment of the modified RBFPDs was not directly related to the surface area of the castings, nor was it related to the type of resin cement, but rather to mechanical interlocking of the castings with the retentive-slot resin composite restorations.