The aim of this study was to describe the changes in oral health policies and guidelines in respo... more The aim of this study was to describe the changes in oral health policies and guidelines in response to the Coronavirus disease 2019 (COVID-19) pandemic in different countries and regions around the world. Information on oral health policies and guidelines from 9 countries (Canada, China including Hong Kong, Egypt, India, Japan, New Zealand, Nigeria, Switzerland, and Thailand) were summarized, and sources of the information were mostly the national or regional health authorities and/or dental council/associations. The changes made to the oral health guidelines depended on the severity of the COVID-19 pandemic. This included suspension of non-emergency dental care services at the peak of the COVID-19 outbreak, and easing the restrictions on non-essential and elective dental care when the pandemic became under control. The COVID-19 risk mitigation strategies include strict adherence to infection control practices (use of hand sanitizers, facemask and maintaining social distancing), re...
Purpose: To compare the mechanical properties and fracture behaviour of laser-sintered/3D-printed... more Purpose: To compare the mechanical properties and fracture behaviour of laser-sintered/3D-printed cobalt chromium (LS CoCr) with soft-milled cobalt chromium (SM CoCr) to assess their suitability for use in high-stress areas in the oral cavity. Material and Method: Two computer-aided manufacturing methods were used to fabricate dumbbell specimens in accordance with the ASTM standard E8. Specimens were fractured using tensile testing and elastic modulus, and proof stress and ultimate tensile strength were calculated. Fracture surfaces were examined using scanning electron microscopy. Plate specimens were also fabricated for the examination of hardness and elastic modulus using nanoindentation. Unpaired t-test was used to evaluate statistical significance. Results: LS CoCr specimens were found to have significantly higher ultimate tensile strength (UTS) and proof stress (PS) (p < 0.05) but not a significantly higher elastic modulus (p > 0.05). Examination of the dumbbell fracture...
C linical stability of dental implants is the combination of primary stability and secondary stab... more C linical stability of dental implants is the combination of primary stability and secondary stability. Primary stability is derived from the initial engagement of the implant to bone and is affected by site (bone quantity and quality), operator (drilling sequence and surgical technique), and design of the implants. 1 Primary stability is essential to eliminate the micromotion that may be detrimental to the healing process. 2-4 With time, healing and regeneration take place and contribute to the development of secondary stability while the bone responsible for initial stability undergoes remodeling. 5-7 As a result, peri-implant bone should demonstrate little changes once the equilibrium phase is achieved. 8 Various methods for assessing and monitoring the degree of osseointegration/ implant stability have been suggested. Histomorphometric analysis via direct examination of bone-to-implant contact is considered to be the gold standard 9 ; however, it is not clinically practical for patients. 10 Mechanical tests, including failure pull-out force, failure lateral load, and failure torque 11 or push-out tests, 2,3 were commonly used in earlier studies, but they also have limited clinical applications due to their destructive natures. 12 They also only assess an "all or none" outcome that does not Purpose: To retrospectively assess implant stability quotient (ISQ) values in patients who were followed up between 1998 and 2014 and to evaluate any correlations between ISQ and clinical parameters, such as change in marginal bone level (MBL). Materials and Methods: A total of 173 participants (65 men and 108 women; age range 21 to 85 years) and 383 implants were included. Implant location, MBL, and ISQ were recorded at surgery and at various recall times for statistical analysis. Mixed-model analysis was applied to evaluate the impact of clinical and demographic variables (time, implant location, patient gender) on ISQ and the correlation between ISQ and MBL. The level of significance was set at P < .05. Results: Of the 21 failed implants, 20 failed within 1 year of functional loading, resulting in a 10-year cumulative implant survival estimate of 95%. The failed implants had lower ISQs at surgery (52.3 ± 7.03) and baseline (52.5 ± 4.20) when compared to surviving implants (63.0 ± 10.74 at surgery and 62.3 ± 8.30 at baseline), and the difference was statistically significant at surgery (P < .05). The mean ISQs generally increased over time, but there were various patterns of changes between implants when grouped according to patient gender and implant location. There was no statistically significant correlation between the changes in ISQ and MBL (P = .211), despite an inverse relationship. Conclusion: Low initial ISQ values may help to identify implants at higher risk of failure. There may be various patterns of change over time in addition to an overall increase in ISQ values. Both similar and contradictory findings were found when compared to earlier literature, and a correlation between resonance frequency analysis and MBL change could not be identified. Despite limitations, the present study provides an overview of the clinical performance of RFA based on long-term clinical data.
The aim of this study was to measure continuously the intraoral pH and temperature of healthy ind... more The aim of this study was to measure continuously the intraoral pH and temperature of healthy individuals to investigate their diurnal variations. MATERIALS AND METHODS: Seventeen participants (mean age, 31 ± 9 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for two sets of 24 h, while carrying out normal daily activities including sleep. The continuous changes in intraoral pH and temperature were captured using a sensor placed on the palatal aspect of the upper central incisors. The collected data were categorised into different status (awake and sleep) and periods (morning, afternoon, evening and night). Both quantitative and qualitative analyses were conducted. RESULTS: The intraoral pH change was found to show a distinctive daily rhythm, showing a 12-h interval between maximum (7.73) and minimum (6.6) pH values. The maximum and minimum values were found to repeat after 24 h. The mean pH over 48 h (two sets of 24 h) was found to be 7.27 (±0.74). There was significant difference found in pH when subjects were awake and asleep and different periods during the day (P o 0.001). The mean intraoral temperature was 33.99°C (±4.9), with less distinctive daily rhythm compared with pH. There was a significant difference found in temperature depending on the time of the day, except between morning and afternoon (P = 0.78). CONCLUSION: Our results showed that there is a distinctive daily, circadian-like pattern in intraoral pH variation over a 24-h period, which has been considered as one of the risk factors in sleep-related dental diseases.
The severity of tooth wear is known to have an association with intraoral pH and temperature depe... more The severity of tooth wear is known to have an association with intraoral pH and temperature depending on the site. OBJECTIVE: To compare the intraoral pH and temperature between the maxillary and mandibular arch. METHODS: Fourteen participants (mean age = 25.8 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for 24 h while carrying out normal activities including sleep. All participants wore a maxillary appliance; four participants repeated the process and wore the mandibular appliance. Measurements were taken from the palatal aspect of the upper central incisors and lingual aspect of the lower canines. Both qualitative and quantitative statistical analyses were conducted. RESULTS: The mean intraoral pH from the maxilla was 7.32 (±0.52) and 7.07 (±0.26) for the mandible. During daytime, there was no statistical significance difference between the two arches (P = 0.12). During sleep, there was a significant difference (P o 0.001) between the mean pH of the maxilla, 7.0 (±0.46), and mandible, 6.46 (±0.31). The fluctuation patterns of pH and temperature from both arches were similar, but the maxilla showed more variations. The mean temperature from the mandible was slightly higher (36.18°C (±0.96)) than the maxilla, 33.12°C (±5.51) during daytime; however, there was no statistically significance difference in temperature between the arches during daytime (awake) or sleep (P = 0.27). CONCLUSION: The results showed that there is significant difference in mean intraoral pH between the maxilla and the mandible during sleep, but not during the day and this difference may be associated variations in tooth wear between the arches.
Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or ... more Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer-aided manufacturing. Research on material for use in additive manufacturing is ongoing, and a wide variety of materials are being used or developed for use in dentistry. Some materials, however, such as cobalt chromium, still lack sufficient research to allow definite conclusions about the suitability of their use in clinical dental practice. Despite this, due to the wide variety of machines that use additive manufacturing, there is much more flexibility in the build material and geometry when building structures compared with subtractive manufacturing. Overall additive manufacturing produces little material waste and is energy efficient when compared to subtractive manufacturing, due to passivity and the additive layering nature of the build process. Such features make the technique suitable to be used with fabricating structures out of hard to handle materials such as cobalt chromium. The main limitations of this technology include the appearance of steps due to layering of material and difficulty in fabricating certain material generally used in dentistry for use in 3D printing such as ceramics. The current pace of technological development, however, promises exciting possibilities.
Maxillofacial prosthetics includes restoration of maxillary defects resulting from resection of p... more Maxillofacial prosthetics includes restoration of maxillary defects resulting from resection of palate and naso-sinus neoplasms with obturator prostheses, which may be colonised by microorganisms and function as a reservoir of infection. These patients commonly also require radiotherapy that can result in changes in oral flora and in saliva quality and quantity. The altered microflora, in individuals immunocompromised from cancer therapy, increases patient risk of prosthesis-related infections. The aim of this study was to investigate microbial adhesion to, and colonisation of, maxillary obturator materials. The influence of saliva on adhesion of bacteria and yeasts to obturator materials was also investigated. This study involved clinical and laboratory components. Clinically, microbial colonisation of obturator prostheses and adjacent tissues was investigated in patients referred for restoration of maxillary defects. This was undertaken at various stages of prosthodontic treatment by taking obturator and tissue swabs, saliva samples and reviewing tissue health. In the laboratory, RAPD PCR was used to identify bacteria and CHROMagar Candida was used to detect yeast species. DNA-DNA checkerboard analysis was also used for microbial detection. Microbial adhesion to obturator materials, and the influence of saliva on adhesion was investigated using static and flow adhesion assays. The analysis of salivary proteins affecting C. albicans adhesion to obturator materials was investigated using Western blot and blot overlay techniques. Identification of possible protein receptors for C. albicans adhesion to obturator materials was carried out by mass spectrometry analysis of the PAGE-separated protein bands. Clinically, obturator prostheses and adjacent tissues in all patients investigated were colonised by Candida, with C. albicans identified in 14 out of 15 patients, at all stages of treatment. Microbial colonisation increased with the age of the prosthesis; the number of microorganisms colonising obturators only reduced following a reline or delivery of a new prosthesis. C. albicans colonisation increased significantly during radiotherapy. All patients with C. albicans colonisation greater than 1x10 5 colony forming units (cfu) per swab after one-week of radiotherapy subsequently required antifungal therapy and/or hospitalisation to manage oral complications during radiotherapy whereas those with C. albicans colonisation ! iii! less than 1x10 4 cfu per swab after one-week didn't require antifungal treatment. This suggests early obturator colonising levels may be a predictor for patient susceptibility to increased morbidity from head and neck radiotherapy. In the laboratory, Staphylococcus epidermidis and C. albicans were identified from swabs of obturators and tissues. S. epidermidis and C. albicans attached to all obturator materials and tended to attach more readily to surfaces with a greater surface roughness and surface energy. Saliva reduced adhesion of S. epidermidis to obturator materials compared with uncoated materials, in contrast, saliva promoted adhesion of C. albicans. Saliva from irradiated patients promoted more adhesion of both S. epidermidis and C. albicans than saliva from controls. Salivary proteins were selectively adsorbed to obturator materials and C. albicans bound to salivary proteins eluted from the same materials. The protein SPLUNC2 was shown, for the first time, to be associated with Candida adhesion to acrylic and may provide receptors for C. albicans adhesion to obturator materials.
Objective: To identify the techniques most commonly used in New Zealand for gingival retraction f... more Objective: To identify the techniques most commonly used in New Zealand for gingival retraction for impressions of natural teeth and implants in fixed prosthodontics. Design: Postal survey of a random sample of dentists Methods: A questionnaire was mailed to all members of the New Zealand Dental Association (NZDA). Data were analysed using SPSS. Results: The response rate was 51%. Veneer, crown and bridge treatments were routinely carried out by 89% of respondents, while implant treatment and/or implantsupported prostheses were provided by 65%. Around natural teeth, gingival retraction was mainly achieved with surgery (including electrosurgery, laser and rotary curettage) and/ or cord, by 82% of dentists. Cord with chemicals was used by 63% and plain cord by 37%. Gingival retraction around implants was used by 18%. Among the latter, the most popular gingival retraction method for use around implants was plain cord (used by 31%), while 25% used cord with chemicals. Another 23% reported using surgery as their means of gingival retraction around implants, while 19% reported using Expasyl™ (Pierre-Roland), and 2% reported using Magic Foam Cord™ (Dentsply), both of which are injectable matrices for gingival retraction. Conclusion: Dentists in New Zealand undertake a considerable amount of fixed prosthodontic and implant work. Gingival retraction around natural teeth is used commonly, while only a small number of participants report using it for implants. A surprising finding was the relatively high number of participants who reported using surgery for gingival retraction around natural teeth.
The term social accountability has gained increased interest in medical education, but is relativ... more The term social accountability has gained increased interest in medical education, but is relatively unexplored in dentistry. The aim of this study is to explore dental students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; attitudes towards social accountability. A qualitative study utilizing focus groups with University of Otago final year (5th year) Bachelor of Dental Surgery (BDS) students was carried out. A questionnaire designed to measure medical students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; attitudes towards social responsibility was used as a guide. Following data collection, framework analysis was used to analyze each of the three focus groups, and repeating themes were noted. Analysis of the focus groups discovered recurring themes, such that participants believed that dentists should be accountable to society in a professional context and that they are responsible for patients who present at their clinic but that there is no professional obligation to help reduce oral health inequalities by working with populations facing inequalities. There was strong agreement that there needs to be change to the dental health care system from a structural and political level to address oral health inequalities, rather than individual dentists assuming greater responsibility. Our findings show that dental education may not be accountable to society in the sense that it is not producing graduates who believe that they have an obligation to address the priority oral health concerns of society.
The aim of this research was to determine the long-term prosthodontic maintenance requirements of... more The aim of this research was to determine the long-term prosthodontic maintenance requirements of mandibular two-implant overdentures using different loading protocols and attachment systems. A total of 106 participants were allocated randomly to one of four different implant systems (Steri-Oss, Southern, Straumann, or Branemark). Three different loading protocols (2, 6, and 12 weeks) were used with six different ball abutment patrices and their respective matrices (Steri-Oss rubber, Straumann gold, Straumann titanium, Branemark gold, Southern plastic, and Southern gold/platinum). Prosthodontic maintenance events were documented prospectively from baseline until the 8-year recall according to predefined categories. After 6 years, 90 participants attended recall and, thereafter, 68 participants were followed for 8 years. No significant differences were found between the number of prosthodontic maintenance events and the loading protocol used. Steri-Oss rubber matrices had the highest...
Limited clinical research identifies prosthodontic maintenance requirements of mandibular overden... more Limited clinical research identifies prosthodontic maintenance requirements of mandibular overdentures using the Locator attachment system. Sixty-five edentulous participants received complete maxillary dentures opposing mandibular two-implant overdentures with either Locator nylon (n = 21), Southern plastic (n = 24), or Straumann gold (n = 20) matrices. Prosthodontic maintenance was recorded prospectively for 3 years using defined categories. Over the 3-year period, a mean 3.52 ± 4.8, 2.08 ± 1.9, and 5.5 ± 4.2 maintenance events occurred for Locator, Southern, and Straumann participants, respectively. Prosthodontic success rates of 90% in the Locator nylon group, 88% in the Southern plastic group, and 75% in the Straumann gold group were achieved. Int J Prosthodont 2011;24:328-331.
According to the glossary of prosthodontic terms, temporomandibular disorders (TMD) are defined a... more According to the glossary of prosthodontic terms, temporomandibular disorders (TMD) are defined as: "Conditions producing abnormal, incomplete or impaired function of the temporomandibular joint(s)" or "a collection of symptoms related to the masticatory system, frequently observed in various combinations" (van Blarcom et al., 2005). Others have defined TMD as a collective term, embracing several clinical problems involving the muscles, temporomandibular joint (TMJ), or both (Okeson, 1996). TMDs form a cluster of related disorders with common symptoms which include localised pain, limited or asymmetric movement, and clicks or grating on opening. Unfortunately, there appears to be no consensus regarding the definition of a temporomandibular disorder within the literature (Mohlin and Thilander, 1984; Okeson, 2003a), and there is considerable variation among epidemiological studies. These studies report that between 5 and 50% of individuals experience TMD pain (Dwor...
The aim of this study was to review the published literature investigating the accuracy of fit of... more The aim of this study was to review the published literature investigating the accuracy of fit of fixed implant frameworks fabricated using different materials and methods. A comprehensive electronic search was performed through PubMed (MEDLINE) using Boolean operators to combine key words. The search was limited to articles written in English and published through May 2010. In addition, a manual search through articles and reference lists retrieved from the electronic search and peer-reviewed journals was also conducted. A total of 248 articles were retrieved, and 26 met the specified inclusion criteria for the review. The selected articles assessed the fit of fixed implant frameworks fabricated by different techniques. The investigated fabrication approaches were one-piece casting, sectioning and reconnection, spark erosion with an electric discharge machine, computer-aided design/computer-assisted manufacturing (CAD/CAM), and framework bonding to prefabricated abutment cylinders....
The purpose of this article is to discuss the clinical considerations related to increasing the o... more The purpose of this article is to discuss the clinical considerations related to increasing the occlusal vertical dimension (OVD) when restoring a patient's dentition. Thorough extraoral and intraoral evaluations are mandatory to assess the suitability of increasing OVD. In the literature, multiple techniques have been proposed to quantify OVD loss. However, the techniques lack consistency and reliability, which in turn affects the decision of whether to increase the OVD. Therefore, increasing OVD should be determined on the basis of the dental restorative needs and aesthetic demands. In general, a minimal increase in OVD should be applied, though a 5 mm maximum increase in OVD can be justified to provide adequate occlusal space for the restorative material and to improve anterior teeth aesthetics. The literature reflects the safety of increasing the OVD permanently, and although signs and symptoms may develop, these are usually of an interim nature. Whenever indicated, the increase in OVD should be achieved with fixed restorations rather than a removable appliance, due to the predictable patient adaptation. The exception to this is for patients with TMD, where increasing the OVD should still be achieved using removable appliances to control TMD-associated symptoms before considering any form of irreversible procedure.
The aim of this study was to describe the changes in oral health policies and guidelines in respo... more The aim of this study was to describe the changes in oral health policies and guidelines in response to the Coronavirus disease 2019 (COVID-19) pandemic in different countries and regions around the world. Information on oral health policies and guidelines from 9 countries (Canada, China including Hong Kong, Egypt, India, Japan, New Zealand, Nigeria, Switzerland, and Thailand) were summarized, and sources of the information were mostly the national or regional health authorities and/or dental council/associations. The changes made to the oral health guidelines depended on the severity of the COVID-19 pandemic. This included suspension of non-emergency dental care services at the peak of the COVID-19 outbreak, and easing the restrictions on non-essential and elective dental care when the pandemic became under control. The COVID-19 risk mitigation strategies include strict adherence to infection control practices (use of hand sanitizers, facemask and maintaining social distancing), re...
Purpose: To compare the mechanical properties and fracture behaviour of laser-sintered/3D-printed... more Purpose: To compare the mechanical properties and fracture behaviour of laser-sintered/3D-printed cobalt chromium (LS CoCr) with soft-milled cobalt chromium (SM CoCr) to assess their suitability for use in high-stress areas in the oral cavity. Material and Method: Two computer-aided manufacturing methods were used to fabricate dumbbell specimens in accordance with the ASTM standard E8. Specimens were fractured using tensile testing and elastic modulus, and proof stress and ultimate tensile strength were calculated. Fracture surfaces were examined using scanning electron microscopy. Plate specimens were also fabricated for the examination of hardness and elastic modulus using nanoindentation. Unpaired t-test was used to evaluate statistical significance. Results: LS CoCr specimens were found to have significantly higher ultimate tensile strength (UTS) and proof stress (PS) (p < 0.05) but not a significantly higher elastic modulus (p > 0.05). Examination of the dumbbell fracture...
C linical stability of dental implants is the combination of primary stability and secondary stab... more C linical stability of dental implants is the combination of primary stability and secondary stability. Primary stability is derived from the initial engagement of the implant to bone and is affected by site (bone quantity and quality), operator (drilling sequence and surgical technique), and design of the implants. 1 Primary stability is essential to eliminate the micromotion that may be detrimental to the healing process. 2-4 With time, healing and regeneration take place and contribute to the development of secondary stability while the bone responsible for initial stability undergoes remodeling. 5-7 As a result, peri-implant bone should demonstrate little changes once the equilibrium phase is achieved. 8 Various methods for assessing and monitoring the degree of osseointegration/ implant stability have been suggested. Histomorphometric analysis via direct examination of bone-to-implant contact is considered to be the gold standard 9 ; however, it is not clinically practical for patients. 10 Mechanical tests, including failure pull-out force, failure lateral load, and failure torque 11 or push-out tests, 2,3 were commonly used in earlier studies, but they also have limited clinical applications due to their destructive natures. 12 They also only assess an "all or none" outcome that does not Purpose: To retrospectively assess implant stability quotient (ISQ) values in patients who were followed up between 1998 and 2014 and to evaluate any correlations between ISQ and clinical parameters, such as change in marginal bone level (MBL). Materials and Methods: A total of 173 participants (65 men and 108 women; age range 21 to 85 years) and 383 implants were included. Implant location, MBL, and ISQ were recorded at surgery and at various recall times for statistical analysis. Mixed-model analysis was applied to evaluate the impact of clinical and demographic variables (time, implant location, patient gender) on ISQ and the correlation between ISQ and MBL. The level of significance was set at P < .05. Results: Of the 21 failed implants, 20 failed within 1 year of functional loading, resulting in a 10-year cumulative implant survival estimate of 95%. The failed implants had lower ISQs at surgery (52.3 ± 7.03) and baseline (52.5 ± 4.20) when compared to surviving implants (63.0 ± 10.74 at surgery and 62.3 ± 8.30 at baseline), and the difference was statistically significant at surgery (P < .05). The mean ISQs generally increased over time, but there were various patterns of changes between implants when grouped according to patient gender and implant location. There was no statistically significant correlation between the changes in ISQ and MBL (P = .211), despite an inverse relationship. Conclusion: Low initial ISQ values may help to identify implants at higher risk of failure. There may be various patterns of change over time in addition to an overall increase in ISQ values. Both similar and contradictory findings were found when compared to earlier literature, and a correlation between resonance frequency analysis and MBL change could not be identified. Despite limitations, the present study provides an overview of the clinical performance of RFA based on long-term clinical data.
The aim of this study was to measure continuously the intraoral pH and temperature of healthy ind... more The aim of this study was to measure continuously the intraoral pH and temperature of healthy individuals to investigate their diurnal variations. MATERIALS AND METHODS: Seventeen participants (mean age, 31 ± 9 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for two sets of 24 h, while carrying out normal daily activities including sleep. The continuous changes in intraoral pH and temperature were captured using a sensor placed on the palatal aspect of the upper central incisors. The collected data were categorised into different status (awake and sleep) and periods (morning, afternoon, evening and night). Both quantitative and qualitative analyses were conducted. RESULTS: The intraoral pH change was found to show a distinctive daily rhythm, showing a 12-h interval between maximum (7.73) and minimum (6.6) pH values. The maximum and minimum values were found to repeat after 24 h. The mean pH over 48 h (two sets of 24 h) was found to be 7.27 (±0.74). There was significant difference found in pH when subjects were awake and asleep and different periods during the day (P o 0.001). The mean intraoral temperature was 33.99°C (±4.9), with less distinctive daily rhythm compared with pH. There was a significant difference found in temperature depending on the time of the day, except between morning and afternoon (P = 0.78). CONCLUSION: Our results showed that there is a distinctive daily, circadian-like pattern in intraoral pH variation over a 24-h period, which has been considered as one of the risk factors in sleep-related dental diseases.
The severity of tooth wear is known to have an association with intraoral pH and temperature depe... more The severity of tooth wear is known to have an association with intraoral pH and temperature depending on the site. OBJECTIVE: To compare the intraoral pH and temperature between the maxillary and mandibular arch. METHODS: Fourteen participants (mean age = 25.8 years) wore a custom-made intraoral appliance fitted with a pH probe and thermocouple for 24 h while carrying out normal activities including sleep. All participants wore a maxillary appliance; four participants repeated the process and wore the mandibular appliance. Measurements were taken from the palatal aspect of the upper central incisors and lingual aspect of the lower canines. Both qualitative and quantitative statistical analyses were conducted. RESULTS: The mean intraoral pH from the maxilla was 7.32 (±0.52) and 7.07 (±0.26) for the mandible. During daytime, there was no statistical significance difference between the two arches (P = 0.12). During sleep, there was a significant difference (P o 0.001) between the mean pH of the maxilla, 7.0 (±0.46), and mandible, 6.46 (±0.31). The fluctuation patterns of pH and temperature from both arches were similar, but the maxilla showed more variations. The mean temperature from the mandible was slightly higher (36.18°C (±0.96)) than the maxilla, 33.12°C (±5.51) during daytime; however, there was no statistically significance difference in temperature between the arches during daytime (awake) or sleep (P = 0.27). CONCLUSION: The results showed that there is significant difference in mean intraoral pH between the maxilla and the mandible during sleep, but not during the day and this difference may be associated variations in tooth wear between the arches.
Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or ... more Additive manufacturing or 3D printing is becoming an alternative to subtractive manufacturing or milling in the area of computer-aided manufacturing. Research on material for use in additive manufacturing is ongoing, and a wide variety of materials are being used or developed for use in dentistry. Some materials, however, such as cobalt chromium, still lack sufficient research to allow definite conclusions about the suitability of their use in clinical dental practice. Despite this, due to the wide variety of machines that use additive manufacturing, there is much more flexibility in the build material and geometry when building structures compared with subtractive manufacturing. Overall additive manufacturing produces little material waste and is energy efficient when compared to subtractive manufacturing, due to passivity and the additive layering nature of the build process. Such features make the technique suitable to be used with fabricating structures out of hard to handle materials such as cobalt chromium. The main limitations of this technology include the appearance of steps due to layering of material and difficulty in fabricating certain material generally used in dentistry for use in 3D printing such as ceramics. The current pace of technological development, however, promises exciting possibilities.
Maxillofacial prosthetics includes restoration of maxillary defects resulting from resection of p... more Maxillofacial prosthetics includes restoration of maxillary defects resulting from resection of palate and naso-sinus neoplasms with obturator prostheses, which may be colonised by microorganisms and function as a reservoir of infection. These patients commonly also require radiotherapy that can result in changes in oral flora and in saliva quality and quantity. The altered microflora, in individuals immunocompromised from cancer therapy, increases patient risk of prosthesis-related infections. The aim of this study was to investigate microbial adhesion to, and colonisation of, maxillary obturator materials. The influence of saliva on adhesion of bacteria and yeasts to obturator materials was also investigated. This study involved clinical and laboratory components. Clinically, microbial colonisation of obturator prostheses and adjacent tissues was investigated in patients referred for restoration of maxillary defects. This was undertaken at various stages of prosthodontic treatment by taking obturator and tissue swabs, saliva samples and reviewing tissue health. In the laboratory, RAPD PCR was used to identify bacteria and CHROMagar Candida was used to detect yeast species. DNA-DNA checkerboard analysis was also used for microbial detection. Microbial adhesion to obturator materials, and the influence of saliva on adhesion was investigated using static and flow adhesion assays. The analysis of salivary proteins affecting C. albicans adhesion to obturator materials was investigated using Western blot and blot overlay techniques. Identification of possible protein receptors for C. albicans adhesion to obturator materials was carried out by mass spectrometry analysis of the PAGE-separated protein bands. Clinically, obturator prostheses and adjacent tissues in all patients investigated were colonised by Candida, with C. albicans identified in 14 out of 15 patients, at all stages of treatment. Microbial colonisation increased with the age of the prosthesis; the number of microorganisms colonising obturators only reduced following a reline or delivery of a new prosthesis. C. albicans colonisation increased significantly during radiotherapy. All patients with C. albicans colonisation greater than 1x10 5 colony forming units (cfu) per swab after one-week of radiotherapy subsequently required antifungal therapy and/or hospitalisation to manage oral complications during radiotherapy whereas those with C. albicans colonisation ! iii! less than 1x10 4 cfu per swab after one-week didn't require antifungal treatment. This suggests early obturator colonising levels may be a predictor for patient susceptibility to increased morbidity from head and neck radiotherapy. In the laboratory, Staphylococcus epidermidis and C. albicans were identified from swabs of obturators and tissues. S. epidermidis and C. albicans attached to all obturator materials and tended to attach more readily to surfaces with a greater surface roughness and surface energy. Saliva reduced adhesion of S. epidermidis to obturator materials compared with uncoated materials, in contrast, saliva promoted adhesion of C. albicans. Saliva from irradiated patients promoted more adhesion of both S. epidermidis and C. albicans than saliva from controls. Salivary proteins were selectively adsorbed to obturator materials and C. albicans bound to salivary proteins eluted from the same materials. The protein SPLUNC2 was shown, for the first time, to be associated with Candida adhesion to acrylic and may provide receptors for C. albicans adhesion to obturator materials.
Objective: To identify the techniques most commonly used in New Zealand for gingival retraction f... more Objective: To identify the techniques most commonly used in New Zealand for gingival retraction for impressions of natural teeth and implants in fixed prosthodontics. Design: Postal survey of a random sample of dentists Methods: A questionnaire was mailed to all members of the New Zealand Dental Association (NZDA). Data were analysed using SPSS. Results: The response rate was 51%. Veneer, crown and bridge treatments were routinely carried out by 89% of respondents, while implant treatment and/or implantsupported prostheses were provided by 65%. Around natural teeth, gingival retraction was mainly achieved with surgery (including electrosurgery, laser and rotary curettage) and/ or cord, by 82% of dentists. Cord with chemicals was used by 63% and plain cord by 37%. Gingival retraction around implants was used by 18%. Among the latter, the most popular gingival retraction method for use around implants was plain cord (used by 31%), while 25% used cord with chemicals. Another 23% reported using surgery as their means of gingival retraction around implants, while 19% reported using Expasyl™ (Pierre-Roland), and 2% reported using Magic Foam Cord™ (Dentsply), both of which are injectable matrices for gingival retraction. Conclusion: Dentists in New Zealand undertake a considerable amount of fixed prosthodontic and implant work. Gingival retraction around natural teeth is used commonly, while only a small number of participants report using it for implants. A surprising finding was the relatively high number of participants who reported using surgery for gingival retraction around natural teeth.
The term social accountability has gained increased interest in medical education, but is relativ... more The term social accountability has gained increased interest in medical education, but is relatively unexplored in dentistry. The aim of this study is to explore dental students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; attitudes towards social accountability. A qualitative study utilizing focus groups with University of Otago final year (5th year) Bachelor of Dental Surgery (BDS) students was carried out. A questionnaire designed to measure medical students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; attitudes towards social responsibility was used as a guide. Following data collection, framework analysis was used to analyze each of the three focus groups, and repeating themes were noted. Analysis of the focus groups discovered recurring themes, such that participants believed that dentists should be accountable to society in a professional context and that they are responsible for patients who present at their clinic but that there is no professional obligation to help reduce oral health inequalities by working with populations facing inequalities. There was strong agreement that there needs to be change to the dental health care system from a structural and political level to address oral health inequalities, rather than individual dentists assuming greater responsibility. Our findings show that dental education may not be accountable to society in the sense that it is not producing graduates who believe that they have an obligation to address the priority oral health concerns of society.
The aim of this research was to determine the long-term prosthodontic maintenance requirements of... more The aim of this research was to determine the long-term prosthodontic maintenance requirements of mandibular two-implant overdentures using different loading protocols and attachment systems. A total of 106 participants were allocated randomly to one of four different implant systems (Steri-Oss, Southern, Straumann, or Branemark). Three different loading protocols (2, 6, and 12 weeks) were used with six different ball abutment patrices and their respective matrices (Steri-Oss rubber, Straumann gold, Straumann titanium, Branemark gold, Southern plastic, and Southern gold/platinum). Prosthodontic maintenance events were documented prospectively from baseline until the 8-year recall according to predefined categories. After 6 years, 90 participants attended recall and, thereafter, 68 participants were followed for 8 years. No significant differences were found between the number of prosthodontic maintenance events and the loading protocol used. Steri-Oss rubber matrices had the highest...
Limited clinical research identifies prosthodontic maintenance requirements of mandibular overden... more Limited clinical research identifies prosthodontic maintenance requirements of mandibular overdentures using the Locator attachment system. Sixty-five edentulous participants received complete maxillary dentures opposing mandibular two-implant overdentures with either Locator nylon (n = 21), Southern plastic (n = 24), or Straumann gold (n = 20) matrices. Prosthodontic maintenance was recorded prospectively for 3 years using defined categories. Over the 3-year period, a mean 3.52 ± 4.8, 2.08 ± 1.9, and 5.5 ± 4.2 maintenance events occurred for Locator, Southern, and Straumann participants, respectively. Prosthodontic success rates of 90% in the Locator nylon group, 88% in the Southern plastic group, and 75% in the Straumann gold group were achieved. Int J Prosthodont 2011;24:328-331.
According to the glossary of prosthodontic terms, temporomandibular disorders (TMD) are defined a... more According to the glossary of prosthodontic terms, temporomandibular disorders (TMD) are defined as: "Conditions producing abnormal, incomplete or impaired function of the temporomandibular joint(s)" or "a collection of symptoms related to the masticatory system, frequently observed in various combinations" (van Blarcom et al., 2005). Others have defined TMD as a collective term, embracing several clinical problems involving the muscles, temporomandibular joint (TMJ), or both (Okeson, 1996). TMDs form a cluster of related disorders with common symptoms which include localised pain, limited or asymmetric movement, and clicks or grating on opening. Unfortunately, there appears to be no consensus regarding the definition of a temporomandibular disorder within the literature (Mohlin and Thilander, 1984; Okeson, 2003a), and there is considerable variation among epidemiological studies. These studies report that between 5 and 50% of individuals experience TMD pain (Dwor...
The aim of this study was to review the published literature investigating the accuracy of fit of... more The aim of this study was to review the published literature investigating the accuracy of fit of fixed implant frameworks fabricated using different materials and methods. A comprehensive electronic search was performed through PubMed (MEDLINE) using Boolean operators to combine key words. The search was limited to articles written in English and published through May 2010. In addition, a manual search through articles and reference lists retrieved from the electronic search and peer-reviewed journals was also conducted. A total of 248 articles were retrieved, and 26 met the specified inclusion criteria for the review. The selected articles assessed the fit of fixed implant frameworks fabricated by different techniques. The investigated fabrication approaches were one-piece casting, sectioning and reconnection, spark erosion with an electric discharge machine, computer-aided design/computer-assisted manufacturing (CAD/CAM), and framework bonding to prefabricated abutment cylinders....
The purpose of this article is to discuss the clinical considerations related to increasing the o... more The purpose of this article is to discuss the clinical considerations related to increasing the occlusal vertical dimension (OVD) when restoring a patient's dentition. Thorough extraoral and intraoral evaluations are mandatory to assess the suitability of increasing OVD. In the literature, multiple techniques have been proposed to quantify OVD loss. However, the techniques lack consistency and reliability, which in turn affects the decision of whether to increase the OVD. Therefore, increasing OVD should be determined on the basis of the dental restorative needs and aesthetic demands. In general, a minimal increase in OVD should be applied, though a 5 mm maximum increase in OVD can be justified to provide adequate occlusal space for the restorative material and to improve anterior teeth aesthetics. The literature reflects the safety of increasing the OVD permanently, and although signs and symptoms may develop, these are usually of an interim nature. Whenever indicated, the increase in OVD should be achieved with fixed restorations rather than a removable appliance, due to the predictable patient adaptation. The exception to this is for patients with TMD, where increasing the OVD should still be achieved using removable appliances to control TMD-associated symptoms before considering any form of irreversible procedure.
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