Application of Organoselenium in inhibiting Candida albicans biofilm adhesion on 3D printed denture base material

PURPOSE

Denture Stomatitis, a chronic mucosal inflammation associated with Candida albicans, is common among denture wearers. Several health conditions have been linked to chronic Candida infections. The complex, multifactorial nature of denture stomatitis requires the continuous pursuit of effective long-term solutions. The present in vitro study investigated the effect of incorporating organoselenium into 3D-printed denture base resin on Candida albicans adhesion and biofilm formation.

MATERIALS AND METHODS

Thirty disks were fabricated using 3D-printed denture base resin and assigned to 3 experimental groups (10/group): disks without organoselenium (control), disks with 0.5% organoselenium (0.5%SE), and disks with 1% organoselenium (1%SE). Each disk was incubated with approximately 1 × 10⁶ cells/mL of Candida albicans for 48 hours. Microbial viability (CFU/mL) was quantified by the spread plate method, while Confocal laser scanning microscopy and scanning electron microscope were performed for quantifying the biofilm thickness and examining biofilm morphology, respectively. Data were analyzed using One-way ANOVA with Tukey's multiple comparisons test.

RESULTS

CFU/mL was significantly (P<0.05) higher in Control when compared with 0.5%SE and 1%SE, but no significant difference between 0.5%SE and 1%SE. A similar trend was observed with biofilm thickness except that there was no significant difference between the Control and 0.5%SE. There was C. albicans biofilm adhesion on the Control disks, with yeast cells and hyphae formation, whereas on 0.5%SE and 1%SE, there was inhibition of yeast cells transition to hyphae formation.

CONCLUSIONS

Incorporation of organoselenium into 3D-printed denture base resin was effective in reducing Candida albicans biofilm formation and growth on denture base material. This article is protected by copyright. All rights reserved.

Bur choice when removing zirconia restorations

PURPOSE

Removal of zirconia restorations can be challenging and time consuming, requiring dental burs with optimal cutting efficiency to minimize iatrogenic complications. Yet, there are very few burs marketed for this purpose and little evidence of their comparative benefit. This study evaluated one specialized bur and compared its cutting efficiency with three general-purpose burs (one single use and two multiple use) MATERIALS AND METHODS: This study was designed to assess the cutting efficiency of four burs on a high strength zirconia substrate. One of these burs is a multiple use bur marketed for high strength ceramics (Komet 4ZR), another is a single use general-purpose bur (Piranha 837.012 coarse), and two are multiple use general-purpose burs (Brassler 6837.31.012C coarse and Komet 6837.314.012 coarse). The cutting efficiency of each bur was determined by measuring the time taken to perform serial 2 mm cuts into a block of zirconia. Ten burs in each group were tested with repeated cuts until the time taken for a 2 mm cut was twice that of the first 2 mm cut (50% loss of efficiency). This study was performed under reproducible conditions using a custom designed and fabricated rig assembly.

RESULTS

The results demonstrated a statistically significant difference in the cutting efficiency between bur types. The single use general-purpose bur (Piranha 837.012) was the most efficient for all cut numbers p <2.2 × 10^-16 . The performance of all burs decreased with each cut, with cutting efficiency dependent on time point/cut number (p = 0.02). The rate of deterioration varied between burs, but this difference was not sufficient to be statistically significant.

CONCLUSIONS

This study demonstrated that a single use bur is more efficient than 3 multiple use burs. The cutting efficiency of a single use general-purpose bur (Piranha 837.012 coarse) on Cerec Zirconia Mono L was statistically superior to that of multiple patient use burs in this study, including one marketed for use on high strength ceramics. Because single use burs are comparatively inexpensive and require no sterilization, they should be strongly considered for the removal of zirconia restorations. This article is protected by copyright. All rights reserved.

The future of maxillofacial prosthodontics in North America: Part II - A survey

STATEMENT OF PROBLEM

Head and neck care has been transformed by the introduction of advanced digital technologies that will continue to be important change drivers for maxillofacial prosthodontics. Insight into these changes is important in answering the question of whether maxillofacial prosthodontics is appropriately prepared to contribute effectively to future multidisciplinary care of the head and neck.

PURPOSE

The purpose of this survey was to gain insight into the perception of changes experienced by maxillofacial prosthodontists in relation to clinical practice. The findings of this survey may assist the future development of the subspecialty.

MATERIAL AND METHODS

An exploratory cross-sectional survey was conducted by using a convenience sample of members of the American Academy of Maxillofacial Prosthetics. The survey considered 10 domains and 31 questions. Fully completed surveys (164) provided a 59% response. Descriptive statistics used percentage responses to reduce and characterize perceptions across respondents.

RESULTS

Eighty-four percent of the respondents were from the United States. Results should be interpreted based on this cohort. Respondents reported a change in care delivered over the past 10 years (72%), with the most important causes of change attributed to surgery (60%) and advanced digital technologies (56%). Respondents perceived advanced digital technologies as being central to the future of maxillofacial prosthodontics (89%) and important in attracting younger colleagues (88%). Sixty-three percent believed training programs were not providing adequate education and training in the use of advanced digital technology.

CONCLUSIONS

The perception of maxillofacial prosthodontists regarding changes taking place in care delivery was that the most important changes in the past 10 years were attributed to surgery and advanced digital technologies, that persisting pressures related to few institutional positions, that the subspecialty was poorly visible, that remuneration for care was inadequate and referring disciplines did not understand the subspecialty, that advanced digital technologies were considered central to the future of maxillofacial prosthodontics and important to attract younger colleagues to the subspecialty, that barriers to advanced digital technology use included funding for equipment acquisition, institutional funding support, and remuneration for their use in care delivery, and that maxillofacial prosthodontic programs were not providing adequate education and training in advanced digital technologies.

The future of maxillofacial prosthodontics in North America: Part I-Journey to the present

STATEMENT OF PROBLEM

Understanding how maxillofacial prosthodontists are perceiving changes in head and neck care and the impact of advanced digital technologies on maxillofacial prosthodontics is important. However, no studies could be identified that specifically addressed these subjects.

PURPOSE

The purpose of this review of selected literature was to identify issues that guided the development of maxillofacial prosthodontics and the concerns that persist. The review also considered contemporary influences that will affect the future of maxillofacial prosthodontics. The conclusions of the review were used to interpret the results of the exploratory survey reported in Part II.

MATERIAL AND METHODS

The review of selected literature was related to the development of maxillofacial prosthodontics in North America between 1950 and 2018. Literature that was considered relevant to the purpose of the review was included.

RESULTS

The review yielded 37 references of interest: 34 peer-reviewed publications, 1 guideline, 1 historical publication, and 1 website. Periods in the development of maxillofacial prosthodontics in North America were identified as formation, consolidation, and innovation.

CONCLUSIONS

It was concluded that concerns in subspecialty programs and clinical practice had origins in the formation and consolidation periods. These persisting concerns extended into the innovation period. Contemporary influences in head and neck surgery will continue to affect the future of maxillofacial prosthodontics. Advanced digital technologies appeared to be central to driving change. Understanding the evolution of maxillofacial prosthodontics was an important first step in providing context when interpreting the results of a survey of maxillofacial prosthodontists reported as Part II of this work.

3D Volume Rendering and 3D Printing (Additive Manufacturing)

Three-dimensional (3D) volume-rendered images allow 3D insight into the anatomy, facilitating surgical treatment planning and teaching. 3D printing, additive manufacturing, and rapid prototyping techniques are being used with satisfactory accuracy, mostly for diagnosis and surgical planning, followed by direct manufacture of implantable devices. The major limitation is the time and money spent generating 3D objects. Printer type, material, and build thickness are known to influence the accuracy of printed models. In implant dentistry, the use of 3D-printed surgical guides is strongly recommended to facilitate planning and reduce risk of operative complications.

Complete-arch accuracy of intraoral scanners

STATEMENT OF PROBLEM

Intraoral scanners have shown varied results in complete-arch applications.

PURPOSE

The purpose of this in vitro study was to evaluate the complete-arch accuracy of 4 intraoral scanners based on trueness and precision measurements compared with a known reference (trueness) and with each other (precision).

MATERIAL AND METHODS

Four intraoral scanners were evaluated: CEREC Bluecam, CEREC Omnicam, TRIOS Color, and Carestream CS 3500. A complete-arch reference cast was created and printed using a 3-dimensional dental cast printer with photopolymer resin. The reference cast was digitized using a laboratory-based white light 3-dimensional scanner. The printed reference cast was scanned 10 times with each intraoral scanner. The digital standard tessellation language (STL) files from each scanner were then registered to the reference file and compared with differences in trueness and precision using a 3-dimensional modeling software. Additionally, scanning time was recorded for each scan performed. The Wilcoxon signed rank, Kruskal-Wallis, and Dunn tests were used to detect differences for trueness, precision, and scanning time (α=.05).

RESULTS

Carestream CS 3500 had the lowest overall trueness and precision compared with Bluecam and TRIOS Color. The fourth scanner, Omnicam, had intermediate trueness and precision. All of the scanners tended to underestimate the size of the reference file, with exception of the Carestream CS 3500, which was more variable. Based on visual inspection of the color rendering of signed differences, the greatest amount of error tended to be in the posterior aspects of the arch, with local errors exceeding 100 μm for all scans. The single capture scanner Carestream CS 3500 had the overall longest scan times and was significantly slower than the continuous capture scanners TRIOS Color and Omnicam.

CONCLUSIONS

Significant differences in both trueness and precision were found among the scanners. Scan times of the continuous capture scanners were faster than the single capture scanners.

Accuracy of rapid prototype models for head and neck reconstruction

STATEMENT OF PROBLEM

Rapid prototype (RP) models are used in craniofacial reconstructions; however, there are no standards or acceptable limits to ensure accuracy of the fabricated models.

PURPOSE

The purpose of this study was to assess the accuracy of RP models by validating the accuracy of SLA skull models with a coordinate measurement device.

MATERIAL AND METHODS

Stainless steel spheres were located on a dry cadaver skull as fiducial markers, scanned with Multi Detector Computer Tomography (MDCT), and interpreted with software for rapid prototyping. Seven stereolithographic (SLA) models were fabricated and measured with a coordinate measurement device. An Euler rotation transformation calculation was applied to standardize the coordinate system between the control and the models. A paired standard t test (α=.05) was used to compare fiducial marker locations on SLA models with the control.

RESULTS

A significant difference was found between the control and each of the SLA models (P<.001) in the Z axis additive build. Significant dimensional differences were not consistently detected in the X and Y axes. Dimensional deviations fell within the size of the MDCT scans voxel dimensions.

CONCLUSIONS

The greatest discrepancies of medical model fabrication correspond to the largest dimension of the orthotropic voxel volume of the MDCT scan, which is related to the slice thickness of the scan and the Z axis of the RP model. However, the absolute magnitude of the error was small, well within the generally accepted tolerance for patient treatment.

Assisted retention of a hearing device in an implant-retained auricular prosthesis

The use of bone-anchored hearing aids is not possible for all patients who wear an implant-retained auricular prosthesis. For some patients, the external ear canal cannot be occluded with a conventional hearing device. Currently manufactured hearing aids may not readily fit the contours of an implant-retained auricular prosthesis. This article describes a technique that allows a modular hearing aid device to be inserted into a custom "sleeve." With this device, the patient can take advantage of binaural cues.

Practical application of polyurethane and Velcro in maxillofacial prosthetics

A procedure is described for the fabrication of an extraoral prosthesis with an acrylic resin substructure that retains a magnet sealed from the environment by a polyurethane liner. Velcro is used to enhance the bond of the acrylic substructure to the silicone prosthesis. This procedure results in improved retention of the acrylic resin substructure and protection of the magnet with an encapsulating polyurethane liner.

The effect of primers and surface characteristics on the adhesion-in-peel force of silicone elastomers bonded to resin materials

Facial prostheses, when used in conjunction with craniofacial implants, require a retentive matrix to hold attachments and/or magnets. The retentive matrix is usually fabricated with autopolymerizing acrylic resin or a visible light-polymerized resin. The purpose of this study was to compare the adhesion-in-peel force of a silicone adhesive to autopolymerizing polymethyl methacrylate and light-polymerizing urethane dimethacrylate gel with two surface textures: (1) pumice polish only or (2) pumice polish and bead retention, and two surface primers: (1) Dow Corning 1205 primer or (2) Dow Corning S-2260 primer. The 1205 primer produced an adhesion-in-peel force that was statistically significantly stronger (p < 0.05) regardless of which type of resin or surface preparation was used.