SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
This article outlines those considerations which are important in integrating posterior crowns with partial dentures. Planning the support and retention of the denture prior to crown construction will enhance patient treatment. Modification of the crown preparation to incorporate rest seats, retentive areas, guide planes and a planned path of insertion may be necessary.
OBJECTIVES: Permanent deformation is one of the most common mechanical complications that affect denture clasps. This can lead to loss of retention and stability of the prosthesis. The purpose of this study was to apply and validate a nonlinear finite element model for permanent deformation prediction in cast denture clasps. Such a model can enhance the process of design optimization and contribute to minimizing the possibility of this problem. METHODS: Cast clasps made from Ti-6Al-7Nb, Co-Cr and Type IV gold alloys were loaded in three different directions (outside, inside and outside inclined 30 degrees ), and the resulting permanent deformation values were recorded. Nonlinear finite element analysis simulations based on the maximum distortion energy criterion for yielding, were conducted for clasp models that were reproduced according to the dimensions of each experimental specimen. Linear regression analysis for the results of the experiment and simulation was performed to verify the validity of the mathematical models. RESULTS: Deflections required to produce specific amounts of permanent deformation were in close agreement with those recorded experimentally. The R2 value for all bending tests was 0.985 and the linear regression equation expressed in micrometers was [DeflectionFEA=0.976 (DeflectionReal)+34]. SIGNIFICANCE: Permanent deformation behavior in the cast clasps with a relatively wide range of deflections (0-2 mm) can be predicted using the proposed model, which shall enhance the design optimization process of cast clasps for denture prostheses.
PURPOSE: This photoelastic study compared the load transfer characteristics of 2 retention mechanisms in an implant-assisted overdenture prosthesis. MATERIALS AND METHODS: Four implants were incorporated into a photoelastic model of a moderately resorbed edentulous human maxilla. Two retention mechanisms were studied by changing components on the same model and the palateless overdenture. The retention mechanisms studied were bar splint with anterior clip and distal resilient attachments, and solitary ball/O-ring attachments. Loads, ranging from 1.4 to 14.4 kg, were applied to the palatal incline of central incisors and buccal incline of premolars with and without balancing contacts. Stresses developed around all the implants under each loading condition were photographed in the field of a circular polariscope. RESULTS: With both retention mechanisms, protrusive and laterotrusive loads without balancing contacts caused instability of the overdenture, producing minimal stress around the implants in the supporting structure. High intensity stresses indicating intrusion of the posterior implants were noted when the bar/distal resilient attachment overdenture had balancing contacts for protrusive and laterotrusive loads. The posterior implants of ball/O-ring attachment overdenture exhibited high intensity stresses indicating not only intrusion, but also bending, when the occlusion was balanced. CONCLUSIONS: Balanced occlusion was required in both retention mechanisms for stability of the implant-assisted overdenture when clinically acceptable loads were applied. The protrusive and laterotrusive loads were not distributed equitably in either mechanism, since highest stresses occurred at the posterior implants.
Numerous attempts have been made to increase the adhesive qualities of the luting medium. Investigators have attempted to modify the metal surface, the tooth surface, the luting material, or combinations. Although investigations have achieved limited success, the adhesive cement remains an elusive goal of restorative dentistry. This article described the etched-metal attachment mechanism as an intermediate phase between luting medium and adhesive medium. However the bond of the resin to the etched enamel and etched metal is not adhesion. Nevertheless, the continuity and microscopic dimension of the mechanical bond mimics the adhesion desired. Until that adhesive material is developed, the bonding mechanism will serve as an effective substitute. The attachment mechanism described is the basis for an improved restoration. Resin-bonded retention can compensate for insufficient frictional retention or may completely substitute for frictional retention prescribed in a resin-bonded retainer prosthesis. Etched-metal procedures for intracoronal restorations permits conservative tooth preparation, greater retention, and improved support of remaining cusps.
Clinical success of resin-bonded fixed partial dentures is primarily dependent on their long-term retention. Retention rates of resin-bonded prostheses placed in 66 patients treated by three dentists in private practice were evaluated in the present study. Seventy-seven resin-bonded fixed partial dentures were followed over a period of 1 year to 11 years. Thirty (39%) became dislodged, but nine were successfully rebonded; thus there were 21 failures (27%). Prosthesis location and operator expertise minimally influenced the longevity of these restorations, but the luting agents tested in this sample had a profound impact on retention. Debonding rates were excessive for some materials tested, whereas other agents proved to be predictable. Modifications in preparation design that enhanced resistance form were also likely contributors to improved retention rates.
Breakage of a segment of an acrylic resin denture base of a mandibular removable prosthesis may result from inadequate retention and support. The runner bar modification can be a solution for this problem, especially where excessive crown length is to be restored in the mandibular anterior region. A technique is described for placement of a 14-gauge (1.7 mm) round wax runner bar that conforms to the anterior arch form on the removable partial denture wax-up. Wax vertical struts are added between the denture base retention and the runner bar. Improved retention and rigidity, without compromising esthetics and function, can be obtained through use of this procedure.
This report describes the transoral maxillary resection of an odontogenic tumor and prosthetic reconstruction with titanium implants placed horizontally in the residual palate. The treatment provided enabled the removal of the lesion and prosthetic restoration of the missing structures, while maintaining optimal facial esthetics and obtaining support, retention, and stability for the prosthesis (Fig. 5).
A technique is presented whereby a median mandibulotomy of an atrophic edentulous mandible is performed to gain access to an oropharyngeal tumor and is subsequently reapproximated with a four-pin FMI. The procedure allows reduction of the osteotomy site and provides intraoral implants that increase the stability and retentive properties of a mandibular prosthesis.
A pilot study was undertaken to find out the policy of the 23 consultant oral and maxillofacial surgeons in the West Midlands towards removal of miniplates after jaw fractures had healed. All 23 replied. Two consultants did not use miniplates; the other 21 respondents used titanium systems, and two also used a stainless steel system. None of the 21 respondents routinely removed all miniplates. The estimated total of miniplates removed after the fracture had healed ranged between 5% and 40% (mode 5%). The main indications for removal were wound infection or dehiscence, before construction of a prosthesis, patients' concern about permanent retention of an implant, and thermal conductivity. We conclude that miniplates and screws are removed mainly to treat symptoms caused by the implants.
The distal extension base denture may be indicated in situations in which the edentulous area to be restored is without a terminal abutment tooth. There may be significant challenges in providing a prosthesis with sufficient support and retention to make it comfortable without damaging the intra-oral tissues. This can be a greater problem in the mandible as the denture-bearing area is usually much smaller than in the maxilla. This paper considers how distal extension removable prostheses can be designed to restore edentulous spaces.
There are still some difficulties in prosthetic reconstruction of cleft lip and palate patients with conventional prostheses or implant retained prostheses. The most common difficulties are insufficient alveolar bone quality and quantity, inadequate soft tissue, and abutment teeth. The patient we report on was a 23-year-old man with a clinical diagnosis of right incomplete cleft lip and palate combined with midface dysplasia. The maxillary six anterior teeth were reconstructed. The maxillary right central incisor and canine were used as abutments for an extracoronal resilient attachment (ERA) retained removable partial overdenture. The STERN ERA SYSTEM is a hinged resilient attachment with an ideal stress breaking characteristic, a good retentive function, and easy chairside replacement. The 2-year follow-up examination revealed an adequate esthetic appearance with good retention and stability of the prosthesis. A removable partial overdenture using the teeth adjacent to the cleft area as abutments with an adequate attachment design is an alternative method for prosthetic reconstruction of cleft lip and palate deformity.
OBJECTIVE: To acquire teeth and prosthetic conditions of the elderly. METHODS: 1166 patients of over 60 years old had been given prosthetic treatment, and the teeth conditions were analyzed. RESULTS: The average number of missing teeth was 10.25. The maxillary missing teeth were more than mandibular ones. The rate of missing teeth were as follows: maxillary teeth > mandibular teeth; molars > bicuspids > incisors > cuspid. 1120 cases were treated with removable dentures. 59% of the removable partial dentures had free-end saddles. 46 cases were treated with fixed bridges. CONCLUSION: The characteristics of prosthetic patients in the elderly were as follows: a large number of missing teeth and free-end missing teeth, attrition of resident teeth, food impaction, existing-residual root and loosen teeth. Removable denture was the main method of the prosthetic therapy for the elderly patients. Fixed bridge was used when the patient condition was good. The cuspid, treated residual root and the third molar should be used for the retention and support of the prosthesis.
Stapedectomy was performed in sixty-seven ears with tympanosclerotic footplate fixation. This was confined to the footplate in 90% of ears, and there was an association with cholesteatoma and chronic infection. Large fenestra stapedectomy was performed in 91% of cases and the surgical procedure performed was tympanoplasty in 91% of cases. Three cases (4.5%) suffered a dead ear by three years following the procedure, but only one immediately. A variety of surgical procedures were used to reconstruct the tympanic membrane to oval window connection, and the air-bone gap did not depend on the choice of prosthesis in the short term. Retention of the incus led to later increasing air-bone gap, probably due to refixation by tympanosclerosis. Long-term results are analyzed for each method of reconstruction and each category of ossicular status identified at surgery. Small fenestra procedures produced less cochlear hearing loss at high frequencies. Surgical technique is discussed with reference to the pathophysiology of tympanosclerosis, and the role of hearing aids is considered.
The purpose of this article is to identify the incidence of complications and the most common complications associated with single crowns, fixed partial dentures, all-ceramic crowns, resin-bonded prostheses, and posts and cores. A Medline and an extensive hand search were performed on English-language publications covering the last 50 years. The searches focused on publications that contained clinical data regarding success/failure/complications. Within each type of prosthesis, raw data were combined from multiple studies and mean values calculated to determine what trends were noted in the studies. The lowest incidence of clinical complications was associated with all-ceramic crowns (8%). Posts and cores (10%) and conventional single crowns (11%) had comparable clinical complications incidences. Resin-bonded prostheses (26%) and conventional fixed partial dentures (27%) were found to have comparable clinical complications incidences. The 3 most common complications encountered with all-ceramic crowns were crown fracture (7%), loss of retention (2%), and need for endodontic treatment (1%). The 3 most common complications associated with posts and cores were post loosening (5%), root fracture (3%), and caries (2%). With single crowns, the 3 most common complications were need for endodontic treatment (3%), porcelain veneer fracture (3%), and loss of retention (2%). When fixed partial denture studies were reviewed, the 3 most commonly reported complications were caries (18% of abutments), need for endodontic treatment (11% of abutments), and loss of retention (7% of prostheses). The 3 most common complications associated with resin-bonded prostheses were prosthesis debonding (21%), tooth discoloration (18%), and caries (7%).
STATEMENT OF PROBLEM: Facial defects secondary to the treatment of neoplasms, congenital malformations, and trauma result in multiple functional and psychosocial difficulties. Prosthetic rehabilitation attempts to restore these facial disfigurements and may improve the level of function and self-esteem for these patients. However, a limited number of studies have evaluated the change in perceived quality of life after maxillofacial prosthetic rehabilitation. PURPOSE: The purpose of this study was to evaluate patients' perceptions of treatment with adhesive-retained and implant-retained facial prostheses and to assess differences in overall satisfaction with these 2 types of treatments. MATERIAL AND METHODS: In this study, a questionnaire with 28 items was administered for evaluation of perceptions of appearance, comfort, fit and irritation, reliability of retention, frequency of wear, ease of placement and removal, level of self-consciousness, and value of treatment. Subjects were categorized into 2 groups: adhesive-retained group (n=16) and implant-retained group (n=19). Comparisons were made for each item in the questionnaire using Fisher exact tests (alpha=.05). RESULTS: The implant group reported higher positive ratings on all 28 questionnaire items when compared with the adhesive group. Statistically significant (P<.05) differences between the implant and adhesive groups were noted for ease of placement and removal, frequency of wear at home, and quality of retention during various activities, such as home chores and when perspiring or sneezing/coughing. CONCLUSION: The implant-retained facial prosthesis offers significant enhancement over an adhesive-retained prosthesis with respect to ease of use and retention during a variety of daily activities, resulting in greater use of the prosthesis.
This case report describes the clinical and laboratory procedures used in the rehabilitation of a patient treated for oral cancer with surgery and radiation therapy. During surgery, a large portion of the mandible was removed and reconstructed with a bone graft. Following therapy, the patient was left with poor esthetics and difficulties with mastication and speech. The goal of prosthodontic treatment was to improve esthetics and restore function. This was successfully achieved through the placement of dental implants and the construction of an implant retained overdenture. A bar was employed to split the implants together and an O-ring system was chosen for retention. The decision to use this type of prosthesis and attachment selection was based on the patient's dental history, esthetic demands, and the need for stress distribution.
A simpler technique for fabricating a prong denture has been described. The prong denture was placed in the mouth of a patient with an atrophic maxilla, who was suffering from ALS, a disabling motor disease. The patient was unable to manage a conventional denture. With the insertion of a prong denture, the patient experienced greatly increased retention and function of his maxillary prosthesis and a more favorable attitude toward himself and his disease.
Between 1987 and 1990, 57 edentulous patients were treated with overdentures supported by 2 endosseous IMZ implants connected by a bar in the lower jaw. The condition of the peri-implant tissue was evaluated for a loading period ranging from 12 to 57 months (mean 30 months and median 24 months). The evaluation parameters included Plaque Index, Bleeding Index, Gingiva Index, pocket depth, dysesthesia of chin or lip, peri-implant bone loss and loss of implants. During the healing phase prior to the construction of an overdenture, 3 implants were lost. After a healing period of 6 months, these implants were successfully replaced. During the follow-up period, a Plaque Index < or = 1 was observed in 45 patients and an abundance of plaque and calculus was observed in 1 patient. Heavy or profuse bleeding and severe gingival inflammation was observed in 3 patients. The mean pocket depth was 3.6 +/- 1.7 mm. None of the patients experienced lip or chin dysesthesia. Marginal bone loss was observed around 30 (26%) implants. From this study it is concluded that, once proper osseointegration is obtained, 2 IMZ implants connected with a bar in the lower jaw supply a proper base for the support of an overdenture; the condition of the peri-implant tissues is steady and independent of the follow-up time.