How long will it last? The expected longevity of prosthodontic and restorative treatment.

With the Internet facilitating access to vast amounts of free information, dental practitioners face providing treatment for an increasingly informed public. However, the available content is not filtered, and it can be difficult for patients to discriminate between research-informed evidence and "glamorised" material of dubious origin. Patients reasonably expect a return for their investment and want to know how long their treatment will last. Clinicians have an obligation to inform their patients so that they can make reasoned decisions about treatment options. Longevity data are also informative for health agencies setting service schedules for publicly funded treatment, and for determining settlements by insurers such as ACC. Historically, much of the prosthodontic treatment performed in practice has relied heavily on dogma, low-level anecdotal evidence, and clinical case reports. This paper considers the literature on fixed and removable prosthodontic restorations and provides a critical review which can be used practically as the basis for informing patients, and to assist decision-makers in making fair and appropriate judgements.

Evaluating the efficiency of caries removal using an Er:YAG laser driven by fluorescence feedback control.

INTRODUCTION: Caries lesions in dental hard tissues autofluoresce when exposed to light of certain wavelengths, whereas sound tissues do not, and this can be used as an in vitro histological marker for dental caries. Detection of autofluorescence is the basis of KaVo DIAGNOdent™ technology, and provides objective feedback control of laser-stimulated ablation of dental caries for the KaVo Key Laser 3™. This Er:YAG laser operates at 2940nm wavelength, and is effective at removal of infected dental hard tissues. Micro-computed tomography (micro-CT) allows the non-invasive investigation of three-dimensional structures and analysis of mineral density profiles of dentine following laser ablation. OBJECTIVE: To evaluate removal of infected, demineralised dentine by Er:YAG irradiation with a laser feedback mechanism, using micro-CT. DESIGN: 27 carious teeth (1 control) and 1 sound tooth, treated with the KaVo Key Laser 3™ using a KaVo™ non-contact 2060 handpiece at specific feedback settings, were examined using a Skyscan 1172 Micro-CT, to observe the efficiency of demineralised dentine removal. Grey scale images obtained were colour rendered to assist detection of demineralised tissue if present. RESULTS: Complete removal of demineralised tissue occurred with laser-stimulated ablation under feedback control at values of 7 and 8 when measured by micro-CT. At greater values, removal of demineralised dentine was incomplete. CONCLUSION: Examination of dental tissues by micro-CT allowed determination of the efficiency of Er:YAG laser-stimulated ablation. Feedback control of the KaVo Key Laser 3™ appeared to operate like a cut-off switch when infected dentine was eliminated, at a threshold of between 6 and 7.

Effect of the smear layer on a pulp proximity-indicating instrument.

The purpose of the study was to determine the effect of removing or modifying the smear layer on the indication provided by the Prepometer pulp proximity-indicating instrument. Third molars were prepared to produce flat surfaces in the coronal dentine, and control Prepometer LED readings were made. Group E was treated with 18% EDTA and Group T with Tubulicid. Prepometer readings were repeated. Dentine was removed in 0.5 mm increments, and readings repeated until a red LED appeared, indicating a danger of pulp exposure. Distances to the pulp were measured. t test, Wilcoxon signed ranks test (WSR) and ordinal regression (OR) analysis were performed, together with SEM examination. There were significant differences between both test groups and their untreated controls. OR showed that a red LED appeared further from the pulp with EDTA treatment than with no treatment. A red LED appeared closer to the pulp with Tubulicid treatment than with no treatment. SEM showed smear removal in Group E and occlusion of tubules in Group T. Prepometer performance was significantly influenced by treatment with EDTA and Tubulicid. Practitioners would be required to learn to interpret the display of the Prepometer instrument in the context of the tooth under treatment and the surface condition of the cut dentine.

In vitro demineralisation of the cervical region of human teeth.

OBJECTIVE: The aim of this study was to investigate a possible role for demineralisation of the cervical region of human teeth in the development of non-carious cervical lesions (NCCLs). MATERIALS AND METHODS: Freshly extracted human premolars were demineralised and prepared for nanoindentation and scanning electron microscope (SEM) observation. After 1 day or 2 days demineralisation in a solution of pH 4.5, specimens were embedded, cut and polished to 1 µm diamond paste. Nanoindentation was done at the cementum-enamel junction (CEJ) region with an interval of 30 µm, to develop mechanical properties maps. After the indentation, SEM with back-scatter detector was employed to observe the degree of demineralisation at the CEJ. RESULTS: After 1 day and 2 days demineralisation, the mechanical properties of enamel and dentine at the CEJ decreased by ∼50% and ∼90%, respectively. SEM images illustrate that artificial demineralisation generated typical demineralised zones in enamel near the CEJ. Moreover, 2 days demineralisation penetrated the sound enamel at the CEJ, and the dentine beneath was undermined. CONCLUSION AND SIGNIFICANCE: One day and 2 days demineralisation reduced the mechanical properties of teeth at the CEJ significantly. Demineralised enamel and dentine with low mechanical properties are prone to wear and abrasion. The findings of the investigation indicate that acid typical of that produced by dental plaque may compromise the mechanical properties of enamel and dentine at the CEJ to the extent that they would be susceptible to tooth brush abrasion, producing NCCLs.

A suitable base material for composite resin restorations: zinc oxide eugenol.

OBJECTIVE: This in vitro study evaluated the effects of a zinc oxide eugenol (ZOE) base on the mechanical properties of a composite resin restoration. METHODS: Class I cavities were prepared on plastic teeth and filled with ZOE plus composite resin, following standard clinical procedures. The samples were sectioned sagittally and the ZOE-resin interface was exposed. After polishing, nanoindentation was performed on the region near the interface, and elastic modulus and hardness were plotted in the form of a color contour map. SEM was employed to observe the interface between composite resin and ZOE base. RESULTS: In the region close to the ZOE base, the elastic modulus and hardness of composite resin reduced to the values of 9.71+/-0.54 and 0.51+/-0.05 GPa, respectively. Eugenol from ZOE had detrimental effects on the composite resin only to a distance of less than 100 microm from the ZOE base. CONCLUSION: Although eugenol suppresses polymerization slightly, by considering the biological advantages of ZOE, together with the results of the current investigation, ZOE may still be considered a suitable base material for composite resin. Bonding is essential for composite resin restorations over ZOE bases to avoid shrinkage detachment.

A novel instrument to determine pulp proximity.

The aim was to determine whether extracted teeth could be used to test the Prepometer instrument, which indicates pulp proximity with green/amber/red light emitting diodes. Third molars were reduced to a plane in dentine and Prepometer readings made. Dentine was removed in 0.5 mm increments and readings made until only lights 9 or 10 (red) showed. The teeth were sectioned and the dentine thickness measured. Analysis permitted construction of a highly significant predictor-model (p < 0.01), the red/amber light boundary coinciding with a dentine thickness of 2.4 mm. The Prepometer was consistent in predicting pulp proximity but was more sensitive than specified.

The use of endodontically treated teeth as abutments for crowns, fixed partial dentures, or removable partial dentures: a literature review.

Endodontically treated teeth are commonly required to serve as abutments for crowns, fixed partial dentures, or removable partial dentures. Many clinicians are of the opinion that endodontically treated teeth do not serve as well as vital teeth. This article reviews the pertinent literature and seeks to reach a consensus for the use of endodontically treated teeth with each type of prosthesis. With appropriate preparation designs, endodontically treated teeth can serve well as abutments for crowns. As restorations become more complex and involve edentulous spans, some reservations apply. In some fixed partial denture designs, the use of endodontically treated teeth may be contraindicated.

Immediately restored, single-tapered implants in the anterior maxilla: prosthodontic and aesthetic outcomes after 1 year.

BACKGROUND: Conventional implant protocols advocate a two-stage technique with a load-free, submerged healing period. Recent studies suggest that immediate restoration of single implants may be a viable treatment option. PURPOSE: The purpose of this study was to evaluate prosthodontic and aesthetic peri-implant mucosal outcomes of immediately restored, Southern single-tapered implants in the anterior maxilla after 1 year. MATERIALS AND METHODS: Participants (mean age: 43.25 years; range: 23-71 years) satisfying specified inclusion criteria were randomly allocated to conventional two-stage restoration (control group; n=14) and immediate restoration groups (test group; n =14) in a randomized controlled clinical trial. Tapered, roughened-surface Southern implants were placed using a standardized technique, and implant level bone impressions were made. Provisional screw-retained crowns, out of occlusion, were placed at second-stage surgery after 26 weeks for the conventional restoration group, and within 4 hours of implant placement for the immediate restoration group. Both groups had definitive screw-retained metal-ceramic crowns placed in occlusion 8 weeks later. Peri-implant mucosal response and papilla index were recorded 4 weeks after definitive crown placement to allow for mucosal maturation and at 1 year. Prosthodontic and aesthetic outcomes were assessed using established criteria. RESULTS: There were no significant differences within, or between, the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length. There were no significant differences in the implant success rate as determined by radiographic bone loss and stability tests after 1 year. There were no significant differences in prosthodontic maintenance, peri-implant mucosal response, and papilla index between the two groups over 1 year. CONCLUSIONS: Tapered, roughened-surface implants immediately restored with single provisional crowns at surgery and definitive crowns 8 weeks later were as prosthodontically and aesthetically successful as conventionally restored two-stage implants during the first year of service. Restoring single implants immediately with screw-retained crowns is an efficient procedure, but the short-term outcome is by no means superior to a conventional two-stage approach.

A randomized controlled clinical trial of conventional and immediately loaded tapered implants with screw-retained crowns.

PURPOSE: Surgical, prosthodontic, and esthetic outcomes of conventional and immediately loaded, single, tapered, roughened-surface Southern implants in the anterior maxilla that were restored with screw-retained crowns were compared over 1 year. MATERIALS AND METHODS: Standardized surgical and prosthodontic procedures were followed and accepted criteria were used for assessment. RESULTS: There were no significant differences within or between the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length. CONCLUSION: After 1 year, the implants that had been immediately loaded with single provisional crowns at surgery and definitive crowns 8 weeks later were as successful as conventionally loaded 2-stage implants.

Distal implants to modify the Kennedy classification of a removable partial denture: a clinical report.

Dental implants or precision attachments can be used to resolve the bilateral distal extension removable partial denture (RPD) dilemma. This report describes the fabrication of a mandibular implant-supported chromium-cobalt RPD with a combination of bilateral single molar implants and metal ceramic crowns using the principles of the channel-shoulder-pin system. The maxillary arch was restored with splinted metal crowns and a conventional RPD retained by extracoronal precision attachments.

Comparison of two methods for the removal of root canal posts.

OBJECTIVE: To compare the application of ultrasound with the use of an engine-driven trephine bur to remove parallel-sided root canal posts. METHOD AND MATERIALS: Single-rooted human canine teeth were decoronated and prepared to receive preformed titanium posts. The posts were cemented with Panavia F resin cement. Ten teeth acted as controls, 10 had a 4-mm-deep gutter cut around the post using a Masserann trephining bur, and 10 were subjected to 10 minutes of ultrasound. The forces required to dislodge the posts were determined using a universal testing machine, and the data were analyzed using analysis of variance. RESULTS: The only significant difference was between the trephined and ultrasonically energized groups, with the ultrasonic group requiring greater forces for dislodgement. CONCLUSION: Resin composite cement could be removed from around the posts with the trephine bur but with considerable difficulty, and neither method of dislodging the posts was effective.

Effect of thermocycling on the retention of glass-fiber root canal posts.

OBJECTIVE: This study investigated the effects of thermocycling on the retention of glass-fiber and resin posts. METHOD AND MATERIALS: Forty premolar and canine tooth roots were embedded in acrylic blocks shaped to fit into a retention device. The roots were randomly assigned to two groups of 20 to receive either Lightposts or Luscent Anchors which were cemented into 9-mm-deep post spaces, with Panavia F resin cement. Each group was randomly divided into two equal subgroups: one for thermocycling, and the other to serve as a control. The thermocycled specimens were cycled 3,000 times between water baths at 5 degrees C and 55 degrees C, with a dwell time of 60 seconds in each. Control specimens were stored at 37 degrees C. The tensile force required to dislodge each post from its root was recorded and the data analyzed using Student's t tests. RESULTS: There were no significant differences in the forces required to cause post-retention failure between the control and thermocycled specimens. Lightposts were significantly more retentive than Luscent Anchors without thermocycling, but this distinction was not apparent in the thermocycled groups. CONCLUSION: Glass-fiber and resin posts cemented with resin cement offer acceptable levels of retention and are not susceptible to reduced retention from thermocycling. Thermocycling should be given less emphasis in tests for the retention of root canal posts cemented with resin cements.

A comparison of the retention of tooth-colored posts.

OBJECTIVE: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using titanium posts as controls. METHOD AND MATERIALS: Sixty recently extracted single-rooted, caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of 10 for post preparation. Post space preparation was carried out according to the individual manufacturer's instructions. All posts were bonded using Panavia F. A 4-mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a cross-head speed of 5 mm/min were recorded. RESULTS: It was found that the parallel-sided Lightposts were significantly more retentive than all of the other posts. Parapost Fibrewhite posts were more retentive than tapered Lightposts and Snowposts. There was no significant difference between the retention of stainless steel Paraposts and any of the other groups. CONCLUSIONS: Serrated parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. When all groups were considered, post dimension appeared to influence retention, with parallel-sided posts being more retentive than tapered posts.

Mandibular overdentures: professional time for prosthodontic maintenance during the first year of service using three different implant systems.

PURPOSE: The purpose of this study was to evaluate the professional time required for the prosthodontic maintenance events of mandibular implant overdentures during the first year of service using three different implant systems (ITI, Steri-Oss, or Southern). MATERIALS AND METHODS: Seventy-two mandibular implant overdenture patients were allocated to three equal groups, each treated with a different implant system. Data on prosthodontic maintenance events during the first year were categorized and analyzed according to professional time allocation per procedure. RESULTS: The total professional time required to perform all the maintenance events ranged between 29.0 and 34.0 hours and did not differ significantly among the three groups, although there were time differences for matrix activation and replacement. When combining the professional time for all maintenance events for the mandibular overdentures alone, or with the opposing maxillary complete dentures, there were no significant differences between groups. For maintenance of the maxillary dentures, there was an unexplained difference between the Southern group and ITI or Steri-Oss groups (P < .05). CONCLUSION: The prosthodontic maintenance for mandibular implant overdentures required on average 72 to 98 minutes of professional time per patient during the first year of service, depending on the system used.

Mandibular overdentures: comparative evaluation of prosthodontic maintenance of three different implant systems during the first year of service.

PURPOSE: This prospective study evaluated the prosthodontic maintenance requirements during the first year of service of mandibular overdentures supported by two unsplinted implants using three different implant systems. MATERIALS AND METHODS: Seventy-two patients randomly allocated to three equal groups were each provided with a conventional complete maxillary denture and a mandibular overdenture supported by two unsplinted implants. A different implant system was used for each group (Steri-Oss, ITI, or Southern Implants), and their prosthodontic maintenance requirements were compared, primarily for the patrix and matrix. Additional maintenance categories recorded included any type of overdenture fracture, reline or remake of the overdenture, and maintenance of the maxillary denture. RESULTS: Sixty-eight percent of the patients, regardless of implant system, required prosthodontic maintenance in the first year, most commonly for the matrices. The Southern Implants matrices required less maintenance than those of Steri-Oss or ITI (P < .05). Additional overdenture maintenance was required by 28% of patients, irrespective of implant system. When all categories of prosthodontic maintenance were combined, there were no differences between implant groups. Evaluation of overall prosthodontic success using six-field tables revealed statistically significant differences between the three implant systems, with more ITI and Steri-Oss patients than Southern Implants patients requiring overdenture retreatment (repair). CONCLUSION: During the first year of service, the matrix maintenance requirements of Southern Implants were significantly lower than those of the ITI or Steri-Oss groups; this was reflected in the number of retreatment (repair) categories recorded. Although the three systems did not differ significantly for overall prosthodontic maintenance, both the Steri-Oss and the ITI titanium matrices showed problems of clinical significance.