Tooth-Supported Overdentures Revisited

The goal of prosthodontics is to provide a functional prosthesis to restore aesthetics, functions, and masticatory efficiencies. Tooth-supported overdentures are one of the treatment options for removable dentures. This article aims to discuss the advantages and disadvantages of tooth-supported overdentures and the principles of using various overdenture attachments, including non-attachment overdentures. The common treatment options in preparing the overdenture abutment are either with or without abutment coping with or without attachment systems, which were discussed and illustrated. A range of tooth-supported overdenture systems were addressed, from low to high financial implications and treatment complexities. The clinician can choose a system that best fits the patient's condition and expectations. This allows clinicians to decide and consider tooth-supported overdentures as a treatment option before full edentulism. A well-executed tooth-supported overdenture ensures the preservation of alveolar bone, optimizes patient satisfaction in denture treatment, and eventually improves the patient's adaptation when transitioning to complete dentures.

Effect of training on time efficiency and marginal adaptation of computer-aided design/computer-aided manufacturing crowns among dental students

INTRODUCTION

The computer-aided design/computer-aided manufacturing (CAD/CAM) technology has revolutionised dentistry at present. An operator's skills can affect the overall clinical duration and marginal accuracy of the prosthesis fabricated through this workflow. The aim of this study was to assess the effect of CAD/CAM hands-on training compared with that of a self-instructional video on the performance of dental students in digital impression and fabrication of a CAD/CAM crown.

METHODS

In this cross-sectional study, 30 undergraduate dental students were shown a CEREC demonstration video. Each operator then captured a digital impression using the intra-oral scanner, and a crown was subsequently milled. All participants underwent a training course before repeating the process. Marginal discrepancy for each crown on its abutment tooth was measured before and after training using a stereomicroscope and was evaluated using Wilcoxon signed rank test. The duration taken for the process was recorded before and after training and evaluated using paired t-test.

RESULTS

The overall mean ±standard deviation marginal adaptation for the CEREC crowns was 78.15 ± 42.83 μm before training and 52.41 ± 17.12 μm after training. The Wilcoxon signed rank test found significant difference (p < .05) in terms of marginal adaptation of crowns fabricated before and after training. Paired t-tests showed that the time efficiency after training significantly improved compared with that before training.

CONCLUSIONS

Training with guided feedback is crucial to improve the time efficiency of making a digital impression and marginal adaptation of fixed prosthesis using the CAD/CAM technology.

Development and validation of a progressive web application to educate partial denture wearers

Effective delivery of post-insertion instructions is essential for denture care and oral health. This study aimed to develop a progressive web application (PWA) to educate patients' chairside and serve as a reference material. A need analysis was conducted before prototype development. Subsequently, the prototype was subjected to content verification, design appraisal and usability testing. The results of usability testing revealed a user task success rate of 94.4%, with an adjusted Wald 95% confidence interval of 83-100%. User satisfaction assessed using the Single Ease Questionnaire and System Usability Score reported a mean score of 6.13 (95% CI: 5.69-6.55) and 85.9 (95% CI: 82.2-89.6), respectively, indicating good usability. This study highlights the systematic approach of developing an evidence-based educational PWA to meet the usability standards for mobile applications. This PWA is useful in clinical studies to explore mobile technologies' potential in educating denture wearers, especially in the older population.

Effect of educational progressive web application on patient's oral and denture knowledge and hygiene: A randomised controlled trial

This study aimed to evaluate the effect of a novel progressive web application (PWA) on the patient's oral and denture knowledge and hygiene. Fifty-two removable partial denture wearers were randomised to receive education using the PWA, or verbal instructions accompanied by demonstration of hygienic procedures. Changes in the participants' knowledge score, plaque index, gingival index and denture plaque was evaluated during a follow-up period of 3 months. The participants' acceptance of PWA was explored through usage logs and a feedback form. Both groups showed significant improvement in knowledge scores, oral and denture hygiene indices (p < 0.001) after education. The PWA group demonstrated significantly lower gingival index score than control (p = 0.008) at the third month review. In conclusion, there is potential of using mobile application in educating elderly patients and the PWA is a viable option for providing post-denture delivery instructions.

Effect of types of resin cements on the bond strength of fiber post under simulated dives

BACKGROUND

Changes in barometric pressure conditions that occur during flying and diving under hyperbaric oxygen conditions were found to influence the retention of dental restorations.

AIM

This experimental laboratory study aimed to evaluate the bond strength of glass fiber posts after being cemented with self-adhesive resin cement (RelyX™ Unicem, 3M ESPE) and self-etch adhesive resin cement (RelyX™ Ultimate, 3M ESPE) under normal atmospheric pressure and hyperbaric pressure cycles that simulate diving conditions.

METHODS

A total of 40 extracted, single-rooted mandibular premolars were treated endodontically and randomly divided into two groups according to the cements used for fiber post cementation. Each group was further randomly divided into two equal subgroups that were subjected to normal atmospheric pressure conditions and a simulated hyperbaric condition in a hyperbaric chamber. The pull-out bond strength of fiber posts was tested using a universal testing machine. Data were analyzed using one-way analysis of variance with Tukey post-hoc test (p<0.05).

RESULTS

At normal atmospheric pressure the mean value of the pull-out bond strength of RelyX Ultimate cement was significantly higher than that of RelyX Unicem cement. At hyperbaric pressure condition no significant difference was found between the mean values of the pull-out bond strength of RelyX Ultimate and RelyX Unicem cement.

CONCLUSION

Hyperbaric pressure cycles demonstrated improved pull-out bond strength of glass fiber posts in RelyX Unicem cement but did not have significant effect on pull-out bond strength in RelyX Ultimate cement. Both resin cements have similar pull-out bond strength of glass fibers post after simulated dives.

Small bowel evisceration through the anus--report of a case and review of literature

An 84-year-old lady with a history of chronic recurrent rectal prolapse, presented to accident and emergency with a significant portion of small bowel and mesentery protruding out of her anus. The small bowel was not contained within peritoneum, nor was this a pararectal herniation. On examination of the rectum, a longitudinal tear was found in the anterior rectal wall, through which the small bowel had prolapsed. Hours after reducing the small bowel back into the anus, it prolapsed a second time. Due to multiple co-morbidities, this patient was not fit for surgery. The defect was temporarily repaired on the ward and the patient treated with aggressive antibiotic therapy. The patient continued to deteriorate, became septic, acidotic, hypotensive and died a day later.

Increased angiogenic response but deficient arteriolization and abnormal microvessel ultrastructure in critical leg ischaemia

BACKGROUND

Ischaemia is known to induce angiogenesis, but the effects of critical leg ischaemia (CLI) on angiogenesis remain unclear. The aim of this study was to examine the physiological angiogenic response in CLI by investigating the extent of neovascularization, characterizing microvessel subtypes and determining the microvessel ultrastructure.

METHODS

Gastrocnemius muscles were biopsied from 12 patients with CLI and 12 without leg ischaemia. Microvessels were evaluated immunohistochemically using three endothelial markers (anti-CD31, anti-CD34 and PAL-E) and anti-alpha smooth muscle actin (SMA) as a mural cell marker to label arterioles. Ki67 was used to demonstrate active cell proliferation. Further microvessel ultrastructural characteristics were determined by transmission electron microscopy.

RESULTS

The CLI group had significantly higher microvessel density and microvessel : muscle fibre ratio for all endothelial subtypes examined (P < 0.001). PAL-E staining demonstrated the highest increase: 4.7 times higher in CLI muscle. There was no significant difference in alphaSMA-positive microvessel density (P = 0.118) or microvessel: muscle fibre ratio (P = 0.214). Ki67 staining showed no active cell proliferation. Transmission electron microscopy showed CLI microvessels had abnormal morphology, mainly a thick basement membrane.

CONCLUSION

A physiological angiogenic response was found in CLI, but the microvessels had an abnormal ultrastructure. A lack of active cell proliferation suggests that the angiogenic response may have been exhausted.

Prevalence of associated infections in community-acquired spontaneous bacterial peritonitis

OBJECTIVES

The frequency with which other infections occur in association with spontaneous bacterial peritonitis is not known, but has implications for both pathogenesis and management. Spontaneous bacterial peritonitis that occurs in hospitalized patients is mainly a nosocomial infection, the study of which must take into account multiple confounding factors. We conducted a prospective study to compare the clinical features and the frequency of associated infections in patients with community-acquired spontaneous bacterial peritonitis to those of cirrhotic patients with ascites but without spontaneous bacterial peritonitis. Previous studies of spontaneous bacterial peritonitis have not found an infection consistently present at some other site, but those studies did not separate community-acquired from hospital-acquired spontaneous bacterial peritonitis.

METHODS

Over a 5-yr study period, 176 cirrhotic patients with ascites were enrolled and were followed. There were 68 patients who had 83 admissions with spontaneous bacterial peritonitis and 108 patients with 124 admissions without spontaneous bacterial peritonitis. Of the 68 patients with spontaneous bacterial peritonitis, 56 had single episodes of peritonitis and 12 had 27 episodes of recurrent bacterial peritonitis. All episodes of spontaneous bacterial peritonitis were diagnosed within 24 h of admission. All subjects had cultures of ascitic fluid, blood, and urine.

RESULTS

Patients with spontaneous bacterial peritonitis were more often symptomatic than the nonspontaneous bacterial peritonitis patients. Ascites cultures were positive in 63 (76%) episodes of spontaneous bacterial peritonitis. The frequency of bacteremia in the spontaneous bacterial peritonitis group was significantly higher than that of the nonspontaneous bacterial peritonitis (56.6% vs. 4.8%, p < 0.0001). Bacteriuria occurred in 51 episodes of spontaneous bacterial peritonitis compared with only nine in nonspontaneous bacterial peritonitis patients (61.4% vs. 7.3%, p < 0.0001). Bacteriuria was observed even more often in recurrent bacterial peritonitis patients than in single episode bacterial peritonitis patients (77.8% vs. 53.6%, p < 0.0001). Most patients with bacteriuria had no urinary tract symptoms. There was no significant difference between the frequency of pneumonia in spontaneous bacterial peritonitis patients compared with nonspontaneous bacterial peritonitis patients (8.4% vs. 10.5%, p = 0.17).

CONCLUSIONS

Asymptomatic bacteriuria occurs often in association with community-acquired spontaneous bacterial peritonitis.

Posterior cruciate avulsion fracture associated with a large inverted medial tibial osteochondral fragment

A case of traumatic avulsion fracture of the posterior cruciate ligament in association with a large osteochondral fracture of the medial tibial condyle is described. The osteochondral fragment was inverted 180 degrees. Many associated injuries of the posterior cruciate ligament have been described. This unusual combination of fractures to the best of our knowledge has not been reported before. The mechanism of injury and its clinical implications are discussed.

Laser iridotomies in Asian eyes

Argon laser iridotomy and Nd:YAG (Neodymium: Yttrium-Aluminium-Garnet) iridotomy are the two established techniques of laser iridotomies. However, in the thicker and more heavily pigmented Asian irides, they are associated with higher complication and failure rates. A third iridotomy technique that is recently described is the sequential argon-YAG laser iridotomy. Here, both the argon and Nd:YAG laser are used serially at the same sitting to achieve a patent iridotomy. By using the argon to make the initial bore and the Nd:YAG laser to complete the perforation, the technique is able to effectively combine most of the advantages of both lasers whilst avoiding their disadvantages. It is possibly the ideal iridotomy technique to use in the Asian irides.

Case report: pseudoarthrosis complicating ankylosing spondylitis--appearances on magnetic imaging

Development of typical pseudoarthrosis from an acute fracture in the spine of a patient with ankylosing spondylitis is documented by serial radiographs. The magnetic resonance imaging appearances of pseudoarthrosis are correlated with histological findings of the surgical specimen.

Palladium 103 ophthalmic plaque radiotherapy

We compared the ocular radiation distribution of palladium 103 (103Pd) vs iodine 125 (125I) ophthalmic plaques sewn to 12 human donor eyes. We then performed preoperative comparative simulations on the first seven patients to be treated with palladium 103 plaque therapy for choroidal melanoma. The in vitro experiment involved palladium 103 seeds placed into a Silastic seed holder, which was affixed into standard 14-mm gold eye plaques. Then the plaques were sewn onto 12 human donor eyes so as to approximate either the nasal (six eyes) or temporal (six eyes) equator. Three sets of two thermoluminescent dosimeters were used to quantify the amount of radiation delivered by the episcleral plaques. Thermoluminescent dosimeters were sewn to the sclera in three locations: on the center of the cornea, on the sclera beneath the macula, and at the equator in a position opposite the plaque. This experiment was then repeated with iodine 125 seeds and thermoluminescent dosimeters. After the plaques were adjusted to equalize their activity (plaque strength), the palladium 103 plaques were found to deliver less radiation to the three target points. Comparative clinical dosimetry also reflected this difference. Preoperative simulations comparing equal doses to the tumors' apex revealed that the palladium 103 ophthalmic plaques delivered more radiation to the tumor and less radiation to most normal ocular structures.

Intraocular radiation blocking

Iodine-based liquid radiographic contrast agents were placed in normal and tumor-bearing (Greene strain) rabbit eyes to evaluate their ability to block iodine-125 radiation. This experiment required the procedures of tumor implantation, vitrectomy, air-fluid exchange, and 125I plaque and thermoluminescent dosimetry (TLD) chip implantation. The authors quantified the amount of radiation attenuation provided by intraocularly placed contrast agents with in vivo dosimetry. After intraocular insertion of a blocking agent or sham blocker (saline) insertion, episcleral 125I plaques were placed across the eye from episcleral TLD dosimeters. This showed that radiation attenuation occurred after blocker insertion compared with the saline controls. Then computed tomographic imaging techniques were used to describe the relatively rapid transit time of the aqueous-based iohexol compared with the slow transit time of the oil-like iophendylate. Lastly, seven nontumor-bearing eyes were primarily examined for blocking agent-related ocular toxicity. Although it was noted that iophendylate induced intraocular inflammation and retinal degeneration, all iohexol-treated eyes were similar to the control eyes at 7 and 31 days of follow-up. Although our study suggests that intraocular radiopaque materials can be used to shield normal ocular structures during 125I plaque irradiation, a mechanism to keep these materials from exiting the eye must be devised before clinical application.

Thermoradiotherapy of choroidal melanoma. Clinical experience

Thermoradiotherapy (TRT) was used to treat 18 patients with choroidal melanoma. Techniques and clinical observations using a plaque-type device capable of delivering microwave hyperthermia to intraocular tumors are described. Iodine-125 plaque irradiation (48-88 Gy to apex), together with microwave hyperthermia (46 degrees-52.5 degrees C to base), were given to patients during one brachytherapy session. Since October 1985, 15 medium and 3 large-sized tumors were treated. Clinical observations include partial clearing of six vitreous opacities as well as three retinal detachments noted before treatment. Objective measurements of improved visual acuity were noted in seven of the nine cases. All tumors responded to treatment, but one tumor had regrowth and the eye was enucleated. These data suggest that a microwave plaque can be used to deliver hyperthermia to human choroidal melanomas. Within the range of the follow-up period, no side effects that might preclude the use of this hyperthermia system for choroidal melanoma treatment were noted.

Isolation of Ca2+-tolerant myocytes from adult rat heart

A procedure for the isolation of myocytes from adult rat hearts is described. It is based on successive treatments with Ca2+-free medium, disaggregating enzymes (collagenase and hyaluronidase) and mechanical agitation. Several recent isolation methods were compared and their best features were combined, together with some original modifications. A good yield of high purity myocytes with excellent morphological and functional integrity was obtained. The cells are tolerant to physiological concentrations of Ca2+. Cellular levels of ATP, Na+, and K+ are close to those in intact hearts and glucose oxidation rates and succinate exclusion are also close to normal. These characteristics are maintained for periods over 1 h.

Opiate properties of SKF 525A

SKF 525A, a classical inhibitor of microsomal drug-metabolizing enzymes, is structurally similar to the diphenylpropylamine analgesics, and certain reported effects in animals resemble those produced by opiate drugs. In an opiate radioreceptor assay, SKF 525A was 50 times less potent than methadone in the absence of sodium and 10 times less potent in the prescence of sodium. The nature of the sodium effect indicates SKF 525A to have less opiate agonist character than does methadone. In mice, 2 mg of SKF 525A given intraperitoneally induced less profound analgesia on a hot plate (44 degrees C) than did 0.1 mg of methadone. Analgesia by SKF 525A was prevented by pretreatment of the mice with naloxone. In rats, 50 microgram of SKF 525A given intracerebroventricularly was analgesic.