Treatment of a cochlear implant biofilm infection: a potential role for alternative antimicrobial agents

OBJECTIVE:
This study aimed to investigate antimicrobial treatment of an infected cochlear implant, undertaken in an attempt to salvage the infected device.

METHODS:
We used the broth microdilution method to assess the susceptibility of meticillin-sensitive Staphylococcus aureus isolate, cultured from an infected cochlear implant, to common antimicrobial agents as well as to novel agents such as tea tree oil. To better simulate in vivo conditions, where bacteria grow as microcolonies encased in glycocalyx, the bactericidal activity of selected antimicrobial agents against the isolate growing in biofilm were also compared.

RESULTS:
When grown planktonically, the S aureus isolate was susceptible to 17 of the 18 antimicrobials tested. However, when grown in biofilm, it was resistant to all conventional antimicrobials. In contrast, 5 per cent tea tree oil completely eradicated the biofilm following exposure for 1 hour.

CONCLUSION:
Treatment of infected cochlear implants with novel agents such as tea tree oil could significantly improve salvage outcome.

Evaluation of sources of uncertainties in microtensile bond strength of dental adhesive system for different specimen geometries

Objective: The aim of this research is to use finite element analysis (FEA) to quantify the effect of the sample shape and the imperfections induced during the manufacturing process of samples on the bond strength and modes of failure of dental adhesive systems through microtensile test. Using the FEA prediction for individual parameters effect, estimation of expected variation and spread of the microtensile bond strength results for different sample geometries is made. Methods: The estimated stress distributions for three different sample shapes, hourglass, stick and dumbbell predicted by FEA are used to predict the strength for different fracture modes. Parameters such as the adhesive thickness, uneven interface of the adhesive and composite and dentin, misalignment of axis of loading, the existence of flaws such as induced cracks during shaping the samples or bubbles created during application of the adhesive are considered. Microtensile experiments are performed simultaneously to measure bond strength and modes of failure. These are compared with the FEA results. Results: The relative bonding strength and its standard deviation for the specimens with different geometries measured through the microtensile tests confirm the findings of the FEA. The hourglass shape samples show lower tensile bond strength and standard deviation compared to the stick and dumbbell shape samples. ANOVA analysis confirms no significant difference between dumbbell and stick geometry results, and major differences of these two geometries compared to hourglass shape measured values. Induced flaws in the adhesive and misalignment of the angle of application of load have significant effect on the microtensile bond strength. Using adhesive with higher modulus the differences between the bond strength of the three sample geometries increase. Significance: The result of the research clarifies the importance of the sample geometry chosen in measuring the bond strength. It quantifies the effect of the imperfections on the bond strength for each of the sample geometries through a systematic and all embracing study. The results explain the reasons of the large spread of the microtensile test results reported by various researchers working in different labs and the need for standardization of the test method and sample shape used in evaluation of the dentin-adhesive bonding system. © 2007 Academy of Dental Materials.

Analysis of the compressive behaviour of the three-dimensional printed porous titanium for dental implants using a modified cellular solid model

A set of cylindrical porous titanium test samples were produced using the three-dimensional printing and sintering method with samples sintered at 900 °C, 1000 °C, 1100 °C, 1200 °C or 1300 °C. Following compression testing, it was apparent that the stress-strain curves were similar in shape to the curves that represent cellular solids. This is despite a relative density twice as high as what is considered the threshold for defining a cellular solid. As final sintering temperature increased, the compressive behaviour developed from being elastic-brittle to elastic-plastic and while Young's modulus remained fairly constant in the region of 1.5 GPa, there was a corresponding increase in 0.2% proof stress of approximately 40-80 MPa. The cellular solid model consists of two equations that predict Young's modulus and yield or proof stress. By fitting to experimental data and consideration of porous morphology, appropriate changes to the geometry constants allow modification of the current models to predict with better accuracy the behaviour of porous materials with higher relative densities (lower porosity).

Skin-reducing mastectomy and one-stage implant reconstruction with a myodermal flap: A safe and effective technique in risk-reducing and therapeutic mastectomy

Introduction: Immediate reconstruction following mastectomy for breast cancer has been shown to be oncologically safe and associated with improved psychosocial outcomes for patients. Bostwick described a technique for one-stage implant based reconstruction, combining skin-sparing mastectomy with concurrent reduction of the skin envelope. This report reviews the experience of a single centre using skin-reducing mastectomy and one-stage implant reconstruction in both early stage breast cancer and risk-reducing mastectomy, with specific reference to frequency of complications, implant loss and oncological outcomes.

Methods and results: A retrospective review was undertaken to identify women who had undergone skin-reducing mastectomy and one-stage implant reconstruction using a de-epithelialised dermal flap, between October 2008 and October 2012. One hundred and four consecutive mastectomies, with reconstruction, were performed by two surgeons on 64 patients. No complications were seen in 43.8% of patients. At three months, four implants were lost (3.8% of breast reconstructions, 6.3% of patients), due to either peri-implant infection or mastectomy skin flap necrosis. One patient required unplanned return to theatre for evacuation of a haematoma. Minor mastectomy skin flap necrosis was seen in 10 breasts (9.6% of reconstructed breasts) and superficial wound infection in 8 breasts (7.7% of reconstructed breasts). All of these complications were managed conservatively and none required operative intervention. At a median follow up of 35 months (4-53 months) there had been one episode of ipsilateral axillary nodal recurrence.

Conclusion: One-stage implant reconstruction using a myo-dermal flap technique following skin-reducing mastectomy is safe and should be considered in selected patients. Most complications are minor and will resolve with conservative management. Major complications such as implant failure or immediate reoperation, were relatively uncommon (6.3% patients, 3.8% of reconstructed breasts). Early follow-up suggests that oncological outcomes are satisfactory, but longer follow-up is required to substantiate this. (C) 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Effect of shotpeening on sliding wear and tensile behavior of titanium implant alloys

Titanium has good biocompatibility and so its alloys are used as implant materials, but they suffer from having poor wear resistance. This research aims to improve the wear resistance and the tensile strength of titanium alloys potentially for implant applications. Titanium alloys Ti–6Al–4V and Ti–6Al–7Nb were subjected to shotpeening process to study the wear and tensile behavior. An improvement in the wear resistance has been achieved due to surface hardening of these alloys by the process of shotpeening. Surface microhardness of shotpeened Ti–6Al–4V and Ti–6Al–7Nb alloys has increased by 113 and 58 HV(0.5), respectively. After shotpeening, ultimate tensile strength of Ti–6Al–4V increased from 1000 MPa to 1150 MPa, higher than improvement obtained for heat treated titanium specimens. The results confirm that shotpeening pre-treatment improved tensile and sliding wear behavior of Ti–6Al–4V and Ti–6Al–7Nb alloys. In addition, shotpeening increased surface roughness.

Implant-retained overdentures did not have a significant improvement in dietary intake

DESIGN: Randomised controlled trial.

INTERVENTION: Patients aged 65 or above edentate for a minimum of five years, with sufficient bone for two implants in the anterior mandible, were recruited. Those with systemic disease that contraindicated implants or had a low mini-mental state evaluation score were excluded. Patients in both groups had a standard maxillary complete denture fabricated. Patients randomised to the treatment group received a two-implant mandibular overdenture while those in the control group received a standard mandibular complete denture. Three 24-hour dietary recalls were collected by telephone interviews at baseline and at 12 months.

RESULTS: 255 patients were randomised: 128 received a standard complete denture (CD) and 127 a two-implant mandibular overdenture (IOD). 127 patients were available at 12-month follow up, 114 in the CD group and 103 in the IOD group. No significant between-group differences were found.

CONCLUSIONS: Although there is much evidence supporting the adoption of two-implant mandibular overdenture (IOD) treatment as the standard of care for edentate patients, this evidence does not include an improvement in dietary intake at one year for medically healthy independent edentate elders when given no specific dietary counselling.

An analysis of the attitudes of dental patients attending general dental practice in Galway

AIM: To describe the patterns of dental attendance and attitudes towards tooth loss of general dental practice patients in Galway.

OBJECTIVES: 1. To determine the pattern of adult dental attendance in general practices in Galway; and, 2. To examine the oral health attitudes of these patients.

METHOD: Questionnaires were distributed to 311 consecutive adult patients in the waiting rooms of ten general dental practices in Galway, which were randomly selected from the telephone directory.

RESULTS: A total of 254 of the 311 questionnaires distributed were fully completed, returned and included in the results, giving a response rate of 81.7%. A total of 59% of dentate participants attended their dentist for annual or biannual examinations compared to 23% of edentate patients. Some 10.5% of medical card holders and 0.5% of non-medical card holders were edentulous.

CONCLUSIONS: The data from the survey indicated that medical card holders in Galway were more likely to be edentulous than nonmedical card holders. Edentate patients were less likely to be regular dental attenders than dentate patients.

Is the shortened dental arch an underused treatment strategy in the Republic of Ireland?

OBJECTIVES: To determine the proportion of Republic of Ireland 35-44 and 65+ year-olds currently satisfying the criteria for a classic shortened dental arch (SDA) of 20 anterior teeth.

RESEARCH DESIGN: Secondary analysis of data collected in the 2000/02 epidemiological survey of the oral health of Irish adults.

CLINICAL SETTING: Participants underwent a clinical oral examination in health board dental clinics and completed a detailed interview pertaining to dental and general health.

PARTICIPANTS: The analysis is based on a random sample of adults, aged 35 to 44 years (n = 978), and 65 years and older (n = 714).

MAIN OUTCOME MEASURES: The SDA was measured as 20 teeth in the mouth in the positions normally described as from the left second premolar to the right second premolar in each arch.

RESULTS: Only one of the 35-44 year-olds and none of the 65+ year-olds had teeth in their mouths in positions normally described as a classic SDA. However, of the 35-44 year old age group only five patients who had at least a premolar dentition of 20 contiguous teeth had been provided with a removable denture compared to one patient from the 65+ years group.

CONCLUSIONS: Very few older patients in the Republic of Ireland have a SDA based on the measure used. However, very few have been provided with removable dentures where they already possess at least a premolar dentition of 20 contiguous teeth. Suggested reasons for this may include limitations of the data recorded, patient preferences and economic factors.

Prosthodontic care for elderly patients

For older patients, clinicians should consider maintaining teeth and using functionally-orientated treatment strategies as an alternative to removable prostheses. When the remaining dentition has a poor prognosis, key teeth should be preserved as overdenture abutments and a gradual transition to edentulousness planned. Where complete dentures are provided, these can be retained using dental implants to overcome many of the problems associated with conventional replacement dentures.

CLINICAL RELEVANCE: The elderly population of today is better informed and more demanding of oral healthcare providers than previous generations. Clinicians should be aware of all the prosthodontic treatment options available for older patients.

Do removable dental prosthesis have an impact on tooth loss?

DESIGN: A multi-centre randomised controlled study in 14 dental schools. This report is an interim analysis at 3 years.

INTERVENTION: Patients were allocated to either the Removable dental prosthesis group (RPD)-109 patients or the no prosthesis group (SDA) -106 patients. Patients had to be older than 35 years with no molars in the study jaw. Follow-up visits were scheduled at 4 to 8 wks (baseline), at 6 months, and at 1, 2, 3, 4, and 5 yrs after treatment.

OUTCOME MEASURE: Time to loss of first tooth following intervention or no intervention.

RESULTS: 81 patients received a RDP and 69 patients received no treatment in the end. This is a reduction of 26% and 35% respectively from the time when they were randomised to the two groups. Tooth loss occurred in 13 of the RDP group (16% of those who received the RDP, 12% of those allocated to the group at the start) with 5 of these being in the study jaw and 8 in the opposing jaw. Tooth loss occurred in 9 of the SDA group (13% of those who received SDA, 9% of those who were allocated to the group at the start) with 5 in the study jaw and 4 in the opposing jaw. The respective Kaplan-Meier survival rates at 38 months were 0.83 (95% CI: 0.74-0.91) in the RDP group and 0.86 (95% CI: 0.78-0.95) in the SDA group.

CONCLUSIONS: The difference in tooth loss at three years between patients treated with RDP and those not treated with RDP was not significant.