Nicholas Chandler - Academia.edu (original) (raw)

Papers by Nicholas Chandler

Australian endodontic journal : the journal of the Australian Society of Endodontology Inc, 2014

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working l... more The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no signific...

Oral health & preventive dentistry, 2015

To evaluate the frequency, distribution and quality of root canal treatment in an adult Nigerian ... more To evaluate the frequency, distribution and quality of root canal treatment in an adult Nigerian subpopulation and to determine the prevalence of apical periodontitis. The periapical status and length of root fillings of 756 patients attending Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria for the first time were evaluated using full mouth periapical radiographs. The length of the root canal filling was considered 'adequate' if it was ≤ 2 mm from the radiographic apex, 'underfilled' if it was > 2 mm short of the apex, and 'overfilled' if filling material extended beyond the radiographic apex. Periapical status was assessed using the periapical index (PAI) with teeth classified as having apical periodontitis if the score was over 2. Overall, 61.2% of the patients had root-filled teeth and 67.2% featured apical periodontitis. Of the 21,468 teeth examined, 12.2% had been root filled, and of these 41% exhibited apical periodontitis. The prevale...

Journal of endodontics, 2009

The aim of this review was to consider laboratory experiments and clinical studies of calcium hyd... more The aim of this review was to consider laboratory experiments and clinical studies of calcium hydroxide-based root canal sealers. An extensive search of the endodontic literature was made to identify publications related to calcium hydroxide-based root canal sealers. The articles were assessed for the outcome of laboratory and clinical studies on their biological properties and physical characteristics. Comparative studies with other sealers were also considered. Several studies were evaluated covering different properties of calcium hydroxide-based sealers including physical properties, biocompatibility, leakage, adhesion, solubility, antibacterial properties, and periapical healing effect. Calcium hydroxide-based root canal sealers have a variety of physical and biological properties. Comparative studies reveal their mild cytotoxicity, but their antibacterial effects are variable. Further research is required to establish the tissue healing properties of calcium hydroxide in root ...

Journal of Endodontics, 1996

The aim of this study was to investigate four root canal sealers--Pulp Canal Sealer EWT, Sealapex... more The aim of this study was to investigate four root canal sealers--Pulp Canal Sealer EWT, Sealapex, AH26, and Ketac-Endo--for their antibacterial effects within dentinal tubules. Sterile saline served as a control. Sixty-six standardized bovine root specimens were infected with Enterococcus faecalis following smear layer removal. The materials were placed in the lumina, and six specimens from each group were stored for 24 h (48 h for AH26) and 7 days, after which dentin samples were taken from within the lumina using ISO 023 to 035 burs. Powder samples were incubated and the quantity of bacteria present assessed using spectrophotometry. All sealers showed antibacterial activity at 24 h, except Ketac-Endo. The activity of Pulp Canal Sealer EWT was similar at 24 h and 7 days. Sealapex had greater antibacterial effect at 7 days than it did at 24 h. The strongest effects were demonstrated by AH26.

Australian Endodontic Journal, 2014

The aim was to investigate undergraduate students' experiences, perceptions of future practice an... more The aim was to investigate undergraduate students' experiences, perceptions of future practice and self-rated confidence levels across endodontic tasks. After ethical approval, a survey involved all fourth and fifth year students. Quantitative data were analysed in SPSS version 20.0. Qualitative data were analysed using a general inductive approach. The participation rate was 84% (n = 136 of 162). The mean number of canals completed was 2.6 by fourth years and 10.4 by fifth years. Maxillary premolars were the most common first tooth treated. Pulpal factors and root morphology were the most common reasons for experiencing difficulty. Self-rated confidence levels were lower for the more junior students and complex procedures. Students felt that an increased use of extracted natural teeth would be beneficial in their pre-clinical practice. A high level of interest was shown in future specialisation in endodontics. Students may benefit from further didactic teaching or pre-clinical instruction in selected topics. Aust Endod J 2014 bs_bs_banner 1

Journal of Endodontics, 1996

A phantom head simulator was used by 30 dental students to determine the effect of instrument han... more A phantom head simulator was used by 30 dental students to determine the effect of instrument handle diameter on the time taken to complete a manipulative task. No significant differences were found for handles between 2.5 and 5 mm diameter. Almost one-third of the participants thought that gloves were a hindrance, and it was considered that "glove wrap," where layers of glove roll over one another, might be a problem with small handles. Despite these subjective reports, the students performed no better without gloves when using the 2.5 mm handle.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 1999

Since the discovery of x-rays by Röentgen in 1895 and the subsequent rapid acceptance of their va... more Since the discovery of x-rays by Röentgen in 1895 and the subsequent rapid acceptance of their value in dental diagnosis, radiography has become standard in oral care. Radiographs of the jaws often feature radiolucent lesions associated with the apices of symptomless teeth. ...

Journal of the American Dental Association, 2009

Journal of the American Dental Association, 2008

The authors reviewed and compared gingival retraction techniques used for implants and teeth. The... more The authors reviewed and compared gingival retraction techniques used for implants and teeth. The authors searched the literature using article databases Ovid MEDLINE up to May 2008, PubMED and Google Scholar (advanced search) and the following search terms: gingival retraction, implant abutment, impressions, cement-retained implant restoration, impression coping, peri-implant tissue, emergence profile and tissue conditioning. The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed. The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Journal of Oral Science, 2010

Electric pulp testing is one of the pulp vitality tests which aid dentists in diagnosis of the pu... more Electric pulp testing is one of the pulp vitality tests which aid dentists in diagnosis of the pulp status. This test is technique sensitive and hence may elicit false responses. There are some concerns regarding the optimal placement of the probe tip. The threshold value (the lowest electric current at which sensation is perceived) is reached when an adequate number of nerve fibers are stimulated, so the sensation would be greatest where the density of neural distribution is the highest. The purpose of this study was to identify the optimum site for electrode placement in anterior teeth of adults, the threshold values of these teeth using an electric pulp test, and to determine the influence of sex, age, and arch on the outcome. The optimum electrode placement sites and threshold values varied with type of tooth and arch. The maxillary teeth, canines, male gender and increasing age required higher electric current to evoke a sensation, while incisal edges required lower current to evoke a sensation. (J Oral Sci 52, 287-292, 2010)

Journal of Oral Rehabilitation, 2004

Molar crown preparations, as described in the literature, have standard forms dictated by the dem... more Molar crown preparations, as described in the literature, have standard forms dictated by the demands of retention, resistance and the physical properties of materials. Standard designs may not be appropriate for all patients because of ethnic variations in tooth shape, pulp size and dentine thickness. Accurate data on these features could assist clinicians to minimize the risk of accidental pulpal injury. The aim of this study was to compare the first molar crown and pulp dimensions between Asian (Chinese, Korean, Malay) and other ethnic groups, using measurements from the bitewing radiographs of 121 subjects. Comparisons revealed the following significantly different features of Asian first molars: larger total pulp areas in uppers (P < 0AE0005); shorter crowns (P < 0AE0005); narrower upper teeth at the cervix (P < 0AE0005); wider pulps at the cervix of lowers (P < 0AE02); more bulbous crowns (P < 0AE0005 for uppers; P < 0AE01 for lowers), and finally significantly thinner dentine interproximally at the cervix (P = 0AE001 for uppers; P = 0AE011 for lowers). Preparations with wide shoulders could pose hazards to the pulps in Asian subjects. This study emphasizes the value of bitewing films in assessing crown and pulp size and shape before making crown preparations. The experienced practitioner may intuitively include tooth and pulp morphology in treatment planning, but this appears not to be taught or documented in textbooks.

Journal of Oral Rehabilitation, 2004

The aim was to determine whether radiographs provide a clinically useful indication of pulp size ... more The aim was to determine whether radiographs provide a clinically useful indication of pulp size in diseased/restored human first molar teeth, and to investigate accessibility of pulp tissue for diagnostic testing using laser Doppler flowmetry (LDF). Extracted teeth of known age were collected. Restorative materials were removed and teeth with evidence of pulp exposures excluded. Fifty-six teeth were radiographed from buccal and mesial aspects, and then their crowns were sectioned axiobuccolingually and photographed. Images were digitally scanned and measurements made of the total pulp area (above a line across the most superior part of the pulpal floor) and the pulp area in the clinical crown (superior to a line between the amelocemental junctions). The pulp width at the cervix and the highest point of the pulp were also recorded. Data were analysed using Pearson correlations. Pulp areas within the clinical crowns were significantly larger than indicated by radiographs, by 23% in the case of the clinically attainable buccal view (P < 0 AE 05). Pulps may be more accessible to flowmeter testing than they appear. Absence of pulp tissues in the crown was recorded in equal numbers of teeth on radiographs and sections, but with agreement for only one tooth. Sixteen per cent of the teeth had no pulp area in the clinical crown when sectioned, but might still be suitable for testing using LDF.

Journal of Esthetic and Restorative Dentistry, 2012

Purpose: Atraumatic, oscillating ultrasonic instruments have recently been developed for prosthod... more Purpose: Atraumatic, oscillating ultrasonic instruments have recently been developed for prosthodontic margin finishing. This in vitro observational pilot study aimed to compare the condition of crown preparation margins finished using new ultrasonic instruments with margins finished with conventional rotary instruments.

Journal of Esthetic and Restorative Dentistry, 2012

Ultrasonic instruments have recently been developed for finishing crown preparations. They are su... more Ultrasonic instruments have recently been developed for finishing crown preparations. They are successful in accessing difficult areas on the preparation margin, but their effects on the dentin surface and on bond strength are contradictory. The aim was to evaluate the condition of crown preparation margins finished using new ultrasonic instruments and to assess their effects on dentin bond strength. Characteristics of tooth surfaces prepared using two different ultrasonic protocols were compared; Perfect Margin Shoulder (PMS) (PMS 3, Satelec, Merignac, France) 1, 2, and 3 (complete finishing) versus PMS 1 and 2 (partial finishing). They were assessed using scanning electron microscopy (SEM) and surface roughness analysis. Bonding of composite resin to dentin surfaces prepared with the complete PMS kit was compared with dentin surfaces prepared with finishing diamond burs, using micro-tensile testing. SEM images revealed a clear difference between the two preparation sequences (PMS 1, 2 versus PMS 1, 2, and 3). Surfaces finished using the PMS tips 1, 2, and 3 appeared continuous, even, and smooth compared with PMS tips 1 and 2 only. The additional use of the PMS 3 uncoated tip enhanced smear layer removal. There was no significant difference when comparing the surface roughness obtained with the PMS 1, 2, and 3 protocol with the PMS 1 and 2 only (p &amp;amp;amp;amp;gt; 0.05). Micro-tensile bond strength was not significantly different between the surfaces prepared with the ultrasonic instruments and the surfaces prepared with the diamond burs (p &amp;amp;amp;amp;gt; 0.05). The use of the complete PMS finishing kit (PMS 1, 2, and 3) produced better quality finishing lines than PMS 1 and 2. The use of ultrasonic instruments to prepare dentin resulted in comparable bond strengths to the use of diamond burs. The extremely precise preparation margin possible with ultrasonic instruments improves the quality and accuracy of crown preparations, which may lead to better impressions and closer adaptation of restorations. The complete set of three Perfect Margin Shoulder instruments is recommended, which can produce comparable bond strengths to preparations with rotary instruments.

Journal of Dentistry, 2009

Immature anterior teeth are at high risk of root fracture following root canal treatment. The lit... more Immature anterior teeth are at high risk of root fracture following root canal treatment. The literature was explored to determine the current status for post-endodontic restorative management of these teeth. The authors explored multiple search engine databases to November 2008. Experiments included in the review involved simulated human or animal immature teeth with mineral trioxide aggregate as an apical plug. The experiments were designed to assess and compare the fracture strength of teeth restored with various materials. Studies that did not fulfil inclusion criteria were omitted from the review. Four in vitro studies fulfilled selection criteria and were systematically reviewed. All studies differed in sources of teeth, their simulated immature tooth model and mode of force application. Current evidence, mostly from laboratory studies, suggests the use of composite resin materials placed deep into the coronal aspect of the root canal to impart superior fracture resistance. Further clinical research is needed to assess other reinforcing materials, which include a variety of post systems and luting agents.

International Endodontic Journal, 2003

To: (i) study coronal pulp dimensions in human first molar teeth; (ii) investigate the effects of... more To: (i) study coronal pulp dimensions in human first molar teeth; (ii) investigate the effects of restorations on pulp size; (iii) determine differences in dimensions between teeth of Mongoloid patients and teeth of other ethnic groups; and (iv) record the presence of pulp stones. Bitewing radiographs of 121 subjects (mean age, 20.9 years) were taken under standardized conditions. The films were digitally scanned and nine measurements were made from the image of each first molar. The data were analysed in terms of presence or absence of restorations and in terms of racial group. Differences were examined using Student&#39;s t-test, Pearson correlations and Levene&#39;s test. A total of 445 teeth were analysed. Large crowns were correlated to large pulps. Teeth restored with occlusal and proximal restorations had significantly smaller pulps (P = 0.044 and 0.004, respectively), but no difference was found in pulp area in the clinical crown between the restoration types. Mongoloid crowns were shorter and more bulbous. Pulp areas of maxillary molars and pulp widths at the cervix of mandibular molars were significantly larger in Mongoloids. The pulp area in the clinical crown correlated to pulp horn height for Mongoloids and others and for maxillary and mandibular teeth. No differences were found between the heights of pulp horns in the Mongoloid and other teeth. Four of the pulp measurements demonstrated sexual dimorphism. Stones were present in almost 10% of the subjects, representing 4% of the tooth pulps examined. Even teeth with shallow occlusal restorations had reduced pulp spaces. There were significant differences in pulp and crown dimensions between the teeth of Mongoloid patients and those of other patients.

International Endodontic Journal, 1998

The aim of this study was to investigate sodium hypochlorite (with and without EDTA), chlorhexidi... more The aim of this study was to investigate sodium hypochlorite (with and without EDTA), chlorhexidine, and hydrogen peroxide in varying concentrations when used in sequence or in combination as endodontic irrigants. Sterile saline served as the control. Six standardized bovine incisor root specimens, which had been infected with Enterococcus faecalis (CG 110), were exposed to each solution. Following exposure to the test agents dentine samples were taken from within the lumina using ISO 023 to 035 burs. The dentine powder samples were incubated and the quantity of bacteria present assessed using spectrophotometry. All irrigant regimens were more effective than saline in killing bacteria. Chlorhexidine and sodium hypochlorite were similarly effective. At specific concentrations a synergistic effect was noted when mixtures of chlorhexidine and hydrogen peroxide were under test.

International Endodontic Journal, 1999

The aim of this study was to investigate the pattern of light transmission through teeth of diffe... more The aim of this study was to investigate the pattern of light transmission through teeth of different species and to examine laser light propagation within enamel from various animal sources. Sectioned teeth from five species--pig, horse, sheep, cat and rat--were evaluated. Samples were illuminated individually by a helium-neon laser light from the buccal surface using a probe 0.5 mm in diameter placed at varying angles between 60 and 120 degrees C. The pattern of light transmission was observed macroscopically. Further evaluation of laser light transmission in enamel was achieved using confocal microscopy. In each species, light was transmitted through the tooth to the pulp, but in the cat and the rat, light was also transmitted to the far side of the tooth. Despite the different patterns of enamel in the species, light was transmitted through enamel to dentine. Light from a laser Doppler probe appeared to reach the dental pulp in all the species: however, in the mammals with smaller teeth, light may also have been able to reach the periodontium and thus the reflected signal may not be entirely of pulpal origin.

International Endodontic Journal, 2008

Pulp stones are a frequent finding on bitewing and periapical radiographs but receive relatively ... more Pulp stones are a frequent finding on bitewing and periapical radiographs but receive relatively little attention in textbooks. A review of the literature was therefore performed, initially using the PubMed database and beginning the search with &#39;pulp calcifications&#39; and &#39;pulp stones&#39;. Each term provided more than 400 references, many of which related to pulp calcification in general rather than pulp stones, and focussed largely on the problems these changes presented to clinicians. A manual search using references from this source was carried out. Contemporary textbooks in endodontology were also consulted, and an historic perspective gained from a number of older books and references. The factors involved in the development of the pulp stones are largely unknown. Further research may determine the reasons for their formation, but with current endodontic instruments and techniques this is unlikely to alter their relevance to clinicians.

Endodontic Topics, 2010

ABSTRACT New treatment strategies for direct pulp capping and pulpotomy have shown promising pote... more ABSTRACT New treatment strategies for direct pulp capping and pulpotomy have shown promising potentials for improved outcomes in immature teeth with extensive caries, traumatic pulp exposures, or anatomical anomalies. Preservation and protection of the dental pulp in developing teeth promote root maturation and extend tooth survivability by postponing or even preventing more complex endodontic and restorative care. Early intervention using hydraulic calcium silicate cements such as mineral trioxide aggregate (MTA) stimulates pulpal cell recruitment and differentiation, up‐regulates transformation factors (gene expression), and promotes dentinogenesis. Calcium hydroxide, resin‐modified glass ionomer cements, hydrophilic resins, and formocresol have been shown to be less effective as bioactive agents when used in vital pulp therapy. Improved treatment procedures for pulp preservation include the use of caries detector dye to preserve the remineralizable inner carious layer and the use of sodium hypochlorite as a hemostatic and diagnostic agent to differentiate reversible from irreversible pulpitis. Although stepwise excavation and the use of calcium hydroxide is still being advocated, pulp capping and pulpotomy procedures using calcium silicate‐based cements are becoming widely accepted as more effective procedures. MTA and new hydraulic calcium silicate cements provide biocompatible environments that predictably promote reparative dentin bridge formation when placed under properly bonded and sealed composite restorations. Hydraulic calcium silicate cements appear to provide a promising future for the preservation of pulpal integrity in immature teeth when used with modified and conservative treatment protocols.

Australian endodontic journal : the journal of the Australian Society of Endodontology Inc, 2014

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working l... more The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no signific...

Oral health & preventive dentistry, 2015

To evaluate the frequency, distribution and quality of root canal treatment in an adult Nigerian ... more To evaluate the frequency, distribution and quality of root canal treatment in an adult Nigerian subpopulation and to determine the prevalence of apical periodontitis. The periapical status and length of root fillings of 756 patients attending Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria for the first time were evaluated using full mouth periapical radiographs. The length of the root canal filling was considered 'adequate' if it was ≤ 2 mm from the radiographic apex, 'underfilled' if it was > 2 mm short of the apex, and 'overfilled' if filling material extended beyond the radiographic apex. Periapical status was assessed using the periapical index (PAI) with teeth classified as having apical periodontitis if the score was over 2. Overall, 61.2% of the patients had root-filled teeth and 67.2% featured apical periodontitis. Of the 21,468 teeth examined, 12.2% had been root filled, and of these 41% exhibited apical periodontitis. The prevale...

Journal of endodontics, 2009

The aim of this review was to consider laboratory experiments and clinical studies of calcium hyd... more The aim of this review was to consider laboratory experiments and clinical studies of calcium hydroxide-based root canal sealers. An extensive search of the endodontic literature was made to identify publications related to calcium hydroxide-based root canal sealers. The articles were assessed for the outcome of laboratory and clinical studies on their biological properties and physical characteristics. Comparative studies with other sealers were also considered. Several studies were evaluated covering different properties of calcium hydroxide-based sealers including physical properties, biocompatibility, leakage, adhesion, solubility, antibacterial properties, and periapical healing effect. Calcium hydroxide-based root canal sealers have a variety of physical and biological properties. Comparative studies reveal their mild cytotoxicity, but their antibacterial effects are variable. Further research is required to establish the tissue healing properties of calcium hydroxide in root ...

Journal of Endodontics, 1996

The aim of this study was to investigate four root canal sealers--Pulp Canal Sealer EWT, Sealapex... more The aim of this study was to investigate four root canal sealers--Pulp Canal Sealer EWT, Sealapex, AH26, and Ketac-Endo--for their antibacterial effects within dentinal tubules. Sterile saline served as a control. Sixty-six standardized bovine root specimens were infected with Enterococcus faecalis following smear layer removal. The materials were placed in the lumina, and six specimens from each group were stored for 24 h (48 h for AH26) and 7 days, after which dentin samples were taken from within the lumina using ISO 023 to 035 burs. Powder samples were incubated and the quantity of bacteria present assessed using spectrophotometry. All sealers showed antibacterial activity at 24 h, except Ketac-Endo. The activity of Pulp Canal Sealer EWT was similar at 24 h and 7 days. Sealapex had greater antibacterial effect at 7 days than it did at 24 h. The strongest effects were demonstrated by AH26.

Australian Endodontic Journal, 2014

The aim was to investigate undergraduate students' experiences, perceptions of future practice an... more The aim was to investigate undergraduate students' experiences, perceptions of future practice and self-rated confidence levels across endodontic tasks. After ethical approval, a survey involved all fourth and fifth year students. Quantitative data were analysed in SPSS version 20.0. Qualitative data were analysed using a general inductive approach. The participation rate was 84% (n = 136 of 162). The mean number of canals completed was 2.6 by fourth years and 10.4 by fifth years. Maxillary premolars were the most common first tooth treated. Pulpal factors and root morphology were the most common reasons for experiencing difficulty. Self-rated confidence levels were lower for the more junior students and complex procedures. Students felt that an increased use of extracted natural teeth would be beneficial in their pre-clinical practice. A high level of interest was shown in future specialisation in endodontics. Students may benefit from further didactic teaching or pre-clinical instruction in selected topics. Aust Endod J 2014 bs_bs_banner 1

Journal of Endodontics, 1996

A phantom head simulator was used by 30 dental students to determine the effect of instrument han... more A phantom head simulator was used by 30 dental students to determine the effect of instrument handle diameter on the time taken to complete a manipulative task. No significant differences were found for handles between 2.5 and 5 mm diameter. Almost one-third of the participants thought that gloves were a hindrance, and it was considered that &quot;glove wrap,&quot; where layers of glove roll over one another, might be a problem with small handles. Despite these subjective reports, the students performed no better without gloves when using the 2.5 mm handle.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 1999

Since the discovery of x-rays by Röentgen in 1895 and the subsequent rapid acceptance of their va... more Since the discovery of x-rays by Röentgen in 1895 and the subsequent rapid acceptance of their value in dental diagnosis, radiography has become standard in oral care. Radiographs of the jaws often feature radiolucent lesions associated with the apices of symptomless teeth. ...

Journal of the American Dental Association, 2009

Journal of the American Dental Association, 2008

The authors reviewed and compared gingival retraction techniques used for implants and teeth. The... more The authors reviewed and compared gingival retraction techniques used for implants and teeth. The authors searched the literature using article databases Ovid MEDLINE up to May 2008, PubMED and Google Scholar (advanced search) and the following search terms: gingival retraction, implant abutment, impressions, cement-retained implant restoration, impression coping, peri-implant tissue, emergence profile and tissue conditioning. The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed. The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Journal of Oral Science, 2010

Electric pulp testing is one of the pulp vitality tests which aid dentists in diagnosis of the pu... more Electric pulp testing is one of the pulp vitality tests which aid dentists in diagnosis of the pulp status. This test is technique sensitive and hence may elicit false responses. There are some concerns regarding the optimal placement of the probe tip. The threshold value (the lowest electric current at which sensation is perceived) is reached when an adequate number of nerve fibers are stimulated, so the sensation would be greatest where the density of neural distribution is the highest. The purpose of this study was to identify the optimum site for electrode placement in anterior teeth of adults, the threshold values of these teeth using an electric pulp test, and to determine the influence of sex, age, and arch on the outcome. The optimum electrode placement sites and threshold values varied with type of tooth and arch. The maxillary teeth, canines, male gender and increasing age required higher electric current to evoke a sensation, while incisal edges required lower current to evoke a sensation. (J Oral Sci 52, 287-292, 2010)

Journal of Oral Rehabilitation, 2004

Molar crown preparations, as described in the literature, have standard forms dictated by the dem... more Molar crown preparations, as described in the literature, have standard forms dictated by the demands of retention, resistance and the physical properties of materials. Standard designs may not be appropriate for all patients because of ethnic variations in tooth shape, pulp size and dentine thickness. Accurate data on these features could assist clinicians to minimize the risk of accidental pulpal injury. The aim of this study was to compare the first molar crown and pulp dimensions between Asian (Chinese, Korean, Malay) and other ethnic groups, using measurements from the bitewing radiographs of 121 subjects. Comparisons revealed the following significantly different features of Asian first molars: larger total pulp areas in uppers (P < 0AE0005); shorter crowns (P < 0AE0005); narrower upper teeth at the cervix (P < 0AE0005); wider pulps at the cervix of lowers (P < 0AE02); more bulbous crowns (P < 0AE0005 for uppers; P < 0AE01 for lowers), and finally significantly thinner dentine interproximally at the cervix (P = 0AE001 for uppers; P = 0AE011 for lowers). Preparations with wide shoulders could pose hazards to the pulps in Asian subjects. This study emphasizes the value of bitewing films in assessing crown and pulp size and shape before making crown preparations. The experienced practitioner may intuitively include tooth and pulp morphology in treatment planning, but this appears not to be taught or documented in textbooks.

Journal of Oral Rehabilitation, 2004

The aim was to determine whether radiographs provide a clinically useful indication of pulp size ... more The aim was to determine whether radiographs provide a clinically useful indication of pulp size in diseased/restored human first molar teeth, and to investigate accessibility of pulp tissue for diagnostic testing using laser Doppler flowmetry (LDF). Extracted teeth of known age were collected. Restorative materials were removed and teeth with evidence of pulp exposures excluded. Fifty-six teeth were radiographed from buccal and mesial aspects, and then their crowns were sectioned axiobuccolingually and photographed. Images were digitally scanned and measurements made of the total pulp area (above a line across the most superior part of the pulpal floor) and the pulp area in the clinical crown (superior to a line between the amelocemental junctions). The pulp width at the cervix and the highest point of the pulp were also recorded. Data were analysed using Pearson correlations. Pulp areas within the clinical crowns were significantly larger than indicated by radiographs, by 23% in the case of the clinically attainable buccal view (P < 0 AE 05). Pulps may be more accessible to flowmeter testing than they appear. Absence of pulp tissues in the crown was recorded in equal numbers of teeth on radiographs and sections, but with agreement for only one tooth. Sixteen per cent of the teeth had no pulp area in the clinical crown when sectioned, but might still be suitable for testing using LDF.

Journal of Esthetic and Restorative Dentistry, 2012

Purpose: Atraumatic, oscillating ultrasonic instruments have recently been developed for prosthod... more Purpose: Atraumatic, oscillating ultrasonic instruments have recently been developed for prosthodontic margin finishing. This in vitro observational pilot study aimed to compare the condition of crown preparation margins finished using new ultrasonic instruments with margins finished with conventional rotary instruments.

Journal of Esthetic and Restorative Dentistry, 2012

Ultrasonic instruments have recently been developed for finishing crown preparations. They are su... more Ultrasonic instruments have recently been developed for finishing crown preparations. They are successful in accessing difficult areas on the preparation margin, but their effects on the dentin surface and on bond strength are contradictory. The aim was to evaluate the condition of crown preparation margins finished using new ultrasonic instruments and to assess their effects on dentin bond strength. Characteristics of tooth surfaces prepared using two different ultrasonic protocols were compared; Perfect Margin Shoulder (PMS) (PMS 3, Satelec, Merignac, France) 1, 2, and 3 (complete finishing) versus PMS 1 and 2 (partial finishing). They were assessed using scanning electron microscopy (SEM) and surface roughness analysis. Bonding of composite resin to dentin surfaces prepared with the complete PMS kit was compared with dentin surfaces prepared with finishing diamond burs, using micro-tensile testing. SEM images revealed a clear difference between the two preparation sequences (PMS 1, 2 versus PMS 1, 2, and 3). Surfaces finished using the PMS tips 1, 2, and 3 appeared continuous, even, and smooth compared with PMS tips 1 and 2 only. The additional use of the PMS 3 uncoated tip enhanced smear layer removal. There was no significant difference when comparing the surface roughness obtained with the PMS 1, 2, and 3 protocol with the PMS 1 and 2 only (p &amp;amp;amp;amp;gt; 0.05). Micro-tensile bond strength was not significantly different between the surfaces prepared with the ultrasonic instruments and the surfaces prepared with the diamond burs (p &amp;amp;amp;amp;gt; 0.05). The use of the complete PMS finishing kit (PMS 1, 2, and 3) produced better quality finishing lines than PMS 1 and 2. The use of ultrasonic instruments to prepare dentin resulted in comparable bond strengths to the use of diamond burs. The extremely precise preparation margin possible with ultrasonic instruments improves the quality and accuracy of crown preparations, which may lead to better impressions and closer adaptation of restorations. The complete set of three Perfect Margin Shoulder instruments is recommended, which can produce comparable bond strengths to preparations with rotary instruments.

Journal of Dentistry, 2009

Immature anterior teeth are at high risk of root fracture following root canal treatment. The lit... more Immature anterior teeth are at high risk of root fracture following root canal treatment. The literature was explored to determine the current status for post-endodontic restorative management of these teeth. The authors explored multiple search engine databases to November 2008. Experiments included in the review involved simulated human or animal immature teeth with mineral trioxide aggregate as an apical plug. The experiments were designed to assess and compare the fracture strength of teeth restored with various materials. Studies that did not fulfil inclusion criteria were omitted from the review. Four in vitro studies fulfilled selection criteria and were systematically reviewed. All studies differed in sources of teeth, their simulated immature tooth model and mode of force application. Current evidence, mostly from laboratory studies, suggests the use of composite resin materials placed deep into the coronal aspect of the root canal to impart superior fracture resistance. Further clinical research is needed to assess other reinforcing materials, which include a variety of post systems and luting agents.

International Endodontic Journal, 2003

To: (i) study coronal pulp dimensions in human first molar teeth; (ii) investigate the effects of... more To: (i) study coronal pulp dimensions in human first molar teeth; (ii) investigate the effects of restorations on pulp size; (iii) determine differences in dimensions between teeth of Mongoloid patients and teeth of other ethnic groups; and (iv) record the presence of pulp stones. Bitewing radiographs of 121 subjects (mean age, 20.9 years) were taken under standardized conditions. The films were digitally scanned and nine measurements were made from the image of each first molar. The data were analysed in terms of presence or absence of restorations and in terms of racial group. Differences were examined using Student&#39;s t-test, Pearson correlations and Levene&#39;s test. A total of 445 teeth were analysed. Large crowns were correlated to large pulps. Teeth restored with occlusal and proximal restorations had significantly smaller pulps (P = 0.044 and 0.004, respectively), but no difference was found in pulp area in the clinical crown between the restoration types. Mongoloid crowns were shorter and more bulbous. Pulp areas of maxillary molars and pulp widths at the cervix of mandibular molars were significantly larger in Mongoloids. The pulp area in the clinical crown correlated to pulp horn height for Mongoloids and others and for maxillary and mandibular teeth. No differences were found between the heights of pulp horns in the Mongoloid and other teeth. Four of the pulp measurements demonstrated sexual dimorphism. Stones were present in almost 10% of the subjects, representing 4% of the tooth pulps examined. Even teeth with shallow occlusal restorations had reduced pulp spaces. There were significant differences in pulp and crown dimensions between the teeth of Mongoloid patients and those of other patients.

International Endodontic Journal, 1998

The aim of this study was to investigate sodium hypochlorite (with and without EDTA), chlorhexidi... more The aim of this study was to investigate sodium hypochlorite (with and without EDTA), chlorhexidine, and hydrogen peroxide in varying concentrations when used in sequence or in combination as endodontic irrigants. Sterile saline served as the control. Six standardized bovine incisor root specimens, which had been infected with Enterococcus faecalis (CG 110), were exposed to each solution. Following exposure to the test agents dentine samples were taken from within the lumina using ISO 023 to 035 burs. The dentine powder samples were incubated and the quantity of bacteria present assessed using spectrophotometry. All irrigant regimens were more effective than saline in killing bacteria. Chlorhexidine and sodium hypochlorite were similarly effective. At specific concentrations a synergistic effect was noted when mixtures of chlorhexidine and hydrogen peroxide were under test.

International Endodontic Journal, 1999

The aim of this study was to investigate the pattern of light transmission through teeth of diffe... more The aim of this study was to investigate the pattern of light transmission through teeth of different species and to examine laser light propagation within enamel from various animal sources. Sectioned teeth from five species--pig, horse, sheep, cat and rat--were evaluated. Samples were illuminated individually by a helium-neon laser light from the buccal surface using a probe 0.5 mm in diameter placed at varying angles between 60 and 120 degrees C. The pattern of light transmission was observed macroscopically. Further evaluation of laser light transmission in enamel was achieved using confocal microscopy. In each species, light was transmitted through the tooth to the pulp, but in the cat and the rat, light was also transmitted to the far side of the tooth. Despite the different patterns of enamel in the species, light was transmitted through enamel to dentine. Light from a laser Doppler probe appeared to reach the dental pulp in all the species: however, in the mammals with smaller teeth, light may also have been able to reach the periodontium and thus the reflected signal may not be entirely of pulpal origin.

International Endodontic Journal, 2008

Pulp stones are a frequent finding on bitewing and periapical radiographs but receive relatively ... more Pulp stones are a frequent finding on bitewing and periapical radiographs but receive relatively little attention in textbooks. A review of the literature was therefore performed, initially using the PubMed database and beginning the search with &#39;pulp calcifications&#39; and &#39;pulp stones&#39;. Each term provided more than 400 references, many of which related to pulp calcification in general rather than pulp stones, and focussed largely on the problems these changes presented to clinicians. A manual search using references from this source was carried out. Contemporary textbooks in endodontology were also consulted, and an historic perspective gained from a number of older books and references. The factors involved in the development of the pulp stones are largely unknown. Further research may determine the reasons for their formation, but with current endodontic instruments and techniques this is unlikely to alter their relevance to clinicians.

Endodontic Topics, 2010

ABSTRACT New treatment strategies for direct pulp capping and pulpotomy have shown promising pote... more ABSTRACT New treatment strategies for direct pulp capping and pulpotomy have shown promising potentials for improved outcomes in immature teeth with extensive caries, traumatic pulp exposures, or anatomical anomalies. Preservation and protection of the dental pulp in developing teeth promote root maturation and extend tooth survivability by postponing or even preventing more complex endodontic and restorative care. Early intervention using hydraulic calcium silicate cements such as mineral trioxide aggregate (MTA) stimulates pulpal cell recruitment and differentiation, up‐regulates transformation factors (gene expression), and promotes dentinogenesis. Calcium hydroxide, resin‐modified glass ionomer cements, hydrophilic resins, and formocresol have been shown to be less effective as bioactive agents when used in vital pulp therapy. Improved treatment procedures for pulp preservation include the use of caries detector dye to preserve the remineralizable inner carious layer and the use of sodium hypochlorite as a hemostatic and diagnostic agent to differentiate reversible from irreversible pulpitis. Although stepwise excavation and the use of calcium hydroxide is still being advocated, pulp capping and pulpotomy procedures using calcium silicate‐based cements are becoming widely accepted as more effective procedures. MTA and new hydraulic calcium silicate cements provide biocompatible environments that predictably promote reparative dentin bridge formation when placed under properly bonded and sealed composite restorations. Hydraulic calcium silicate cements appear to provide a promising future for the preservation of pulpal integrity in immature teeth when used with modified and conservative treatment protocols.