Scanning Electron Microscopy Observations of Failures of Implant Overdenture Bars: A Case Series Report

Background: Soldered or cast bars are used as a standard of care in attachment systems supporting maxillary and mandibular implant overdentures. When failures of these bars occur, currently there is a lack of evidence in relation to their specific etiology, location, or nature. Purpose: To investigate the failure process of a case series of six failed soldered bars, four intact soldered bars, and one intact cast milled bar, which had been supporting implant overdentures. Materials and Methods: A total of 11 different overdenture bars were removed from patients with different configuration of opposing arches. A failed bar (FB) group (n = 6) had failed soldered overdenture bars, which were recovered from patients following up to 2 years of wear before requiring prosthodontic maintenance and repair. An intact bar (IB) group (n = 5) had both soldered bars and a single cast milled bar, which had been worn by patients for 2 to 5 years prior to receiving other aspects of prosthodontic maintenance. All bars were examined using scanning electron microscopy to establish the possible mode of failure (FB) or to identify evidence of potential failure in the future (IB). Results: Evidence of a progressive failure mode of corrosion fatigue and creep were observed on all the FB and IB usually around the solder areas and nonoxidizing gold cylinder. Fatigue and creep were also observed in all the IB. Where the level of corrosion was substantial, there was no evidence of wear from the matrices of the attachment system. Evidence of an instantaneous failure mode, ductile and brittle overload, was observed on the fracture surfaces of all the FB, within the solder and the nonoxidizing gold cylinders, at the solder/cylinder interface. Conclusion: Corrosion, followed by corrosion fatigue, appears to be a key factor in the onset of the failure process for overdenture bars in this case series of both maxillary and mandibular overdentures. Limited sample size and lack of standardization identify trends only but prevent broad interpretation of the findings.     

The effect of cleaning on blood contamination in the dental surgery following periodontal procedures

Blood contamination of 16 surfaces in the dental surgery was investigated using the Kastle-Meyer test for haemoglobin, after three types of periodontal procedures had been performed on a total of 30 patients. The effect of cleaning surfaces contaminated by blood was investigated using the same test. Cleaning materials used in the dental surgery were tested to rule out the possibility of false positive outcomes and the sensitivity of the test was determined prior to the study. The results show a marked variation in the degree of contamination and efficacy of cleaning following treatment. Overall, root planing was associated with the most widespread and frequent blood contamination and gingival surgery the least. The surgery work surface, edge of the spittoon, aspirator tube and ultrasonic scaler handpiece into which the ultrasonic insert fits, were the most frequently contaminated surfaces. The work surface, dentist's pen, light switch and handle were cleaned most effectively. The least effectively cleaned surfaces were the water dispenser switch, aspirator tube, bracket table and ultrasonic scaler handpiece. Methods for reducing this potential source of crossinfection are discussed.     

Long‐term dental management of a patient with features of Schöpf–Schulz–Passarge syndrome

Schöpf–Schulz–Passarge syndrome (SSPS) is thought to be a rare autosomal recessive condition similar to many other ectodermal dysplasias. Diagnosis is difficult, with many possible differential diagnoses; however, eyelid cysts are a commonly seen feature. This clinical report aims to highlight this and describe the dental features and management of this syndrome, which existing literature has not previously described.