Biomedical subjects

N P Chandler

Publications and source records attributed to N P Chandler.

At least 19 recordsLinked to original sources

PubMed2006

Orthodontic movement of two root fractured teeth: a case report.

AIM: To illustrate significant tipping orthodontic movement of root fractured teeth. SUMMARY: As the frequency of root fractured maxillary teeth is related to increased overjet and reduced lip coverage, orthodontic treatment may increase lip coverage and reduce the risk of trauma or its severity. It may also be necessary to move previously traumatized teeth. Two root fractured teeth were tipped through a considerable angle (19 degrees ) to reduce a large overjet and followed up for 5 years. KEY LEARNING POINTS: -- Reduction of large overjets involving root fractured teeth may not affect pulp vitality. -- Root fragment separation prior to orthodontics did not appear to increase in this patient, but angulation of the fragments did not completely follow the major change to the coronal part of the tooth.

Cephalometry↗

PubMed2005

An evaluation of .06 tapered gutta-percha cones for filling of .06 taper prepared curved root canals.

AIM: To compare the area occupied by gutta-percha, sealer, or void in standardized .06 tapered prepared simulated curved canals and in mesio-buccal canals of extracted maxillary first molars filled with a single .06 gutta-percha point and sealer or lateral condensation of multiple .02 gutta-percha points and sealer. METHODOLOGY: Simulated canals in resin blocks with either a 30 degrees curve and radius of 10.5 mm (n = 20) or a 58 degrees curve and 4.7 mm radius (n = 20) and curved mesio-buccal canals of extracted maxillary first molars (n = 20) were prepared using .06 ProFiles in a variable tip crown-down sequence to an apical size 35 at 0.5 mm from the canal terminus or apical foramen. Ten 30 degrees and 58 degrees curved resin canals and 10 canals in the extracted teeth group were obturated with .02 taper gutta-percha cones and AH 26 sealer using lateral condensation. The time required to obturate was recorded. The remaining canals were obturated with a single .06 taper gutta-percha cone and AH 26 sealer. Excess gutta-percha was removed from the specimens using heat and the warm mass vertically condensed. Horizontal sections were cut at 0.5, 1.5, 2.5, 4.5, 7.5 and 11.5 mm from the canal terminus or apical foramen. Colour photographs were taken using an Olympus 35 mm camera attached to a stereomicroscope set at x40 magnification, and then digitized using a flatbed scanner. The cross-sectional area of the canal contents was analysed using Adobe PhotoShop. The percentage of gutta-percha, sealer or voids to the total root canal area were derived and data analysed using unpaired Student's t-test and the Mann-Whitney U-test. RESULTS: In the 30 degrees curved canals the levels had between 94 and 100% of the area filled with gutta-percha with no significant difference (P > 0.05) between the lateral condensation and single cone techniques. In the 58 degrees curved canals the levels had 92-99% of the area filled with gutta-percha, with the single cone technique having significantly (P < 0.05) more gutta-percha fill at the 2.5 mm level only. In the mesio-buccal canals of the teeth the levels had between 72 and 96% of the area filled with gutta-percha with no significant difference (P > 0.05) between the lateral condensation and single cone technique. The time for obturation was significantly (P < 0.05) greater for lateral condensation compared with the single cone technique in all groups. CONCLUSIONS: The .06 taper single cone technique was comparable with lateral condensation in the amount of gutta-percha occupying a prepared .06 tapered canal. The .06 single cone technique was faster than lateral condensation.

Dental Pulp Cavity↗

PubMed2004

Electronic apex locators.

Prior to root canal treatment at least one undistorted radiograph is required to assess canal morphology. The apical extent of instrumentation and the final root filling have a role in treatment success, and are primarily determined radiographically. Electronic apex locators reduce the number of radiographs required and assist where radiographic methods create difficulty. They may also indicate cases where the apical foramen is some distance from the radiographic apex. Other roles include the detection of root canal perforation. A review of the literature focussed first on the subject of electronic apex location. A second review used the names of apex location devices. From the combined searches, 113 pertinent articles in English were found. This paper reviews the development, action, use and types of electronic apex locators.

Dental Instruments↗

PubMed2004

The bitewing radiograph as an assessment tool in fixed prosthodontics.

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 < 0.0005); shorter crowns (P < 0.0005); narrower upper teeth at the cervix (P < 0.0005); wider pulps at the cervix of lowers (P < 0.02); more bulbous crowns (P < 0.0005 for uppers; P < 0.01 for lowers), and finally significantly thinner dentine interproximally at the cervix (P=0.001 for uppers; P=0.011 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.

Adult↗

PubMed2004

Pulp size in molars: underestimation on radiographs.

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 < 0.05). 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.

Adult↗

PubMed2004

Clarity and diagnostic quality of digitized conventional intraoral radiographs.

OBJECTIVES: To compare digital images of conventional radiographs with the original radiographs for perceived clarity of endodontic files, periapical lesions and carious lesions, and to establish the diagnostic value of the digital images. METHODS: Four groups of ten radiographs were used: standardized bitewings demonstrating carious lesions, periapical radiographs of apical lesions, periapical radiographs showing endodontic files of various sizes at working length, and standardized periapical radiographs with size 08 files at working length. Radiographs were photographed using an Olympus C 2500-L digital camera and a Nikon D1X digital camera and were scanned using a Nikon Supercoolscan 4000 ED film/slide scanner. The digital images were then transferred to a Toshiba Satellite 2210 laptop. Three general dental practitioners compared each conventional radiograph with the three matching digital images. Images were ranked for clarity and were assessed for diagnostic quality. Data were analysed using General Estimating Equations. RESULTS: The clarity and diagnostic quality of the conventional radiographs were superior to the digital images produced by the three techniques (P < 0.001). No significant difference was found between the Nikon D1X and Camedia 2500-L cameras for clarity or diagnostic quality. The scanner was equivalent to the Camedia 2500-L camera for diagnostic quality, but was otherwise inferior to both cameras. CONCLUSIONS: Digitizing conventional radiographs using current high-grade digital cameras or scanners does not produce images of diagnostic quality. Improved resolution of viewing monitors is necessary to fully harness the potential of digital technology.

Computer Terminals↗

PubMed2003

Effect of X-ray beam angulation and intraradicular contrast medium on radiographic interpretation of lower first molar root canal anatomy.

AIMS: To compare evaluator radiographic interpretation of noncontrasted and contrasted root canal anatomy on radiographs taken at a 0 or 30 degrees mesial angle to the orthoradial orientation. METHODOLOGY: Pulp tissue was removed from 20 mandibular first molar teeth using NaOCl irrigation and hand files. Standardized radiographs at 0 and 30 degrees angulation were obtained of each tooth positioned in a dried mandible. Contrast medium (iohexol) was injected passively into the canals and a second pair of corresponding radiographs was obtained. A third pair of radiographs was taken after infusing canals under vacuum with contrast medium. Using set criteria, three evaluators assessed the canal anatomy of the mesial root on radiographs: (i) the number of visible canals, (ii) whether the canal(s) was visible along the entire length of the root, (iii) the location of the canal terminus in relation to the radiographic apex, (iv) configuration of canal(s), (v) level of multiple canals merging and (vi) the presence of lateral canals. The teeth were then cleared for visual assessment. The data were compared using logistic regression and the intra- and interevaluator reliability assessed with the Kappa test. RESULTS: Noncontrasted 0 degrees images were significantly better (P < 0.05) than noncontrasted 30 degrees images for detecting the number of visible canals, whether the canal(s) was visible along the entire length of the root, the location of the canal terminus in relation to the radiographic apex and level of multiple canals merging. The 0 degrees images contrasted by vacuum or passive injection were significantly better (P < 0.05) than 30 degrees images only for assessing whether the canal(s) was visible along the entire length of the root, whilst the 0 degrees image contrasted by passive injection was also better (P < 0.05) at assessing the location of the canal terminus in relation to the radiographic apex. At 30 degrees, contrast medium passively or vacuum introduced improved (P < 0.05) the detection of the number of visible canals, whether the canal(s) was visible along the entire length of the root and configuration of canal(s), whilst vacuum also improved (P < 0.05) the location of the canal terminus in relation to the radiographic apex. Overall, there was no significant difference (P > 0.05) between images contrasted by passive injection or vacuum. CONCLUSIONS: Under the conditions of this study, conventional radiographs taken at a 0 degrees orientation provided more information than 30 degrees radiographs. Contrast medium improved radiographic interpretation of canal anatomy, especially when used with 30 degrees radiographs.

Contrast Media↗

PubMed2003

Factors influencing the removal of posts.

AIM: To determine whether metal type, cement type and the use of ultrasonic vibration influence the amount of tensile force required to remove parallel-sided, prefabricated, metal posts from tooth roots. METHODOLOGY: Ninety extracted canine teeth were sectioned horizontally 1-mm coronal to the labial cemento-enamel junction and embedded in acrylic blocks. Standardized post spaces were prepared with a ParaPost no. 5 (1.25 mm) drill to 10 mm and ParaPost XP no. 5 stainless steel and titanium posts were cemented using zinc phosphate, glass ionomer or composite resin cement. Sixty posts were subjected to 16 min of ultrasonic vibration whilst 30 stainless steel posts received no vibration. The force required for post removal was determined using a universal testing machine. Results were analysed using univariate anova. RESULTS: The univariate anova revealed no statistically significant differences between the groups at the P = 0.05 level. CONCLUSIONS: In this in vitro experiment, metal type, cement type and ultrasonic vibration did not influence the force required to remove posts.

Analysis of Variance↗

PubMed2003

Coronal pulp size in molars: a study of bitewing radiographs.

AIM: 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. METHODOLOGY: 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's t-test, Pearson correlations and Levene's test. RESULTS: 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. CONCLUSION: 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.

Adolescent↗

PubMed2002

Radiographic practices of dentists undertaking endodontics in New Zealand.

OBJECTIVES: To determine the radiographic practices of New Zealand dentists undertaking root canal treatment, and to investigate the relationship between radiographic practices and educational and clinical factors. METHODS: A questionnaire was sent to all 1200 general dental practitioners and five specialist endodontists in New Zealand. Data were subjected to descriptive and analytical statistics. RESULTS: The response rate was 79%. The mean number of root canal treatments done by general dentists in the previous 12 months was 103, and for the specialists 938. Pre-operative views were taken by 57.1% of respondents all the time and by 34.8% in most cases. The long cone paralleling and bisecting angle techniques were in regular use by similar numbers of respondents, and over one half of the practitioners regularly used film holders and electronic apex locators. Working length films were taken by 67% of practitioners all the time and by 18% in most cases. One-quarter of practitioners took a master point view all the time, and 15% did this for most cases. Almost 65% always took a film of the completed root filling and 21% did for most cases. Twenty-three per cent of practitioners did not follow up their work. CONCLUSIONS: The majority of respondents used radiographs pre-operatively, for working length assessment and to assess the final root filling. There was a general improvement in radiographic practices compared with data from a previous national survey held in 1980.

Dental Pulp Cavity↗

PubMed2002

Endodontic implications of the maxillary sinus: a review.

The anatomical and clinical significance of the maxillary sinus in relation to conventional and surgical endodontic therapy is considered. The discussion includes a review on the development, anatomy and physiology of the maxillary sinus, the diagnostic evaluation of the sinus and the differential diagnosis of sinusitis. Endodontic implications of the maxillary sinus include extension of periapical infections into the sinus, the introduction of endodontic instruments and materials beyond the apices of teeth in close proximity to the sinus and the risks and complications associated with endodontic surgery.

Analgesics↗

PubMed2002

Temporization for endodontics.

Teeth undergoing root-canal therapy are susceptible to microbial contamination from oral fluids both during and after treatment. With the exception of single-visit treatment, the use of a temporary restoration is mandatory. This review aims to provide an overview of the materials and techniques used for short- and long-term restorations during and immediately after endodontic treatment, and to make clinical recommendations. Further research is necessary to determine the effectiveness of temporary restorations in the conditions of the oral environment, especially with respect to leakage and functional demands.

Crowns↗

PubMed2002

The changing role of the apicectomy operation in dentistry.

Enormous progress has been made in the last quarter of a century in understanding the nature of root canal infection and periapical disease. New techniques and materials may be expected to increase the already high success of conventional root canal treatment. Surgical intervention is required for cases where retreatment has failed or is not an option, and the tooth is to be retained rather than extracted. This article reviews the operation of apicectomy and how this minor oral surgical procedure has evolved. Recent modifications to techniques and materials are likely to improve its success, allowing conservation of previously unsaveable teeth.

Apicoectomy↗

PubMed2002

Comparison of the cariogenicity of some processed cheeses.

AIM: Cheeses have been investigated for their potential cariogenicity in several studies and have been shown to produce little change in the resting pH in dental plaque and little or no demineralisation of enamel in most intra-oral cariogenicity studies. The aim of the present study was to investigate the cariogenicity of four processed cheese formulations. METHODS: Enamel demineralisation was measured intra-orally in bovine enamel, and aliquots of 10g of each test cheese were used to assess plaque pH using the plaque harvesting technique after the San Antonio criteria. In a second experiment, the same cheeses were assessed for their effects on enamel using the intra-oral cariogenicity test (ICT) with bovine enamel. RESULTS: None of the four cheeses caused pH drops below the critical pH and two of the cheeses raised the pH slightly. The effects on pH were all significantly different from those of the sucrose saliva control. None of the cheeses produced microhardness changes that were statistically significantly different from the saliva control. CONCLUSION: None of these cheeses as tested were found to lead to acidogenicity and by inference to be cariogenic. They were therefore deemed to be safe for teeth when used as a food.

Journal Article↗

PubMed2001

Pattern of transmission of laser light through carious molar teeth.

AIMS: The aims of this study were to investigate the pattern of transmission of laser light through carious human molar teeth, and to examine the effect on light transmission of reactions to caries in the dentine. METHODOLOGY: Sectioned carious human molars were examined whilst illuminated from their external surfaces by a helium-neon laser probe of 0.5 mm diameter. The pattern of light transmission was observed and selected specimens were photographed. The passage of light through the surrounding dentine toward the pulp space was investigated by confocal microscopy. Further carious and restored teeth were illuminated from three buccal and three lingual sites to establish the probability of light being able to reach the coronal pulp space. RESULTS: For all 31 teeth examined, it was possible to illuminate the pulp space from a position on the buccal side. The presence of intracoronal restorations did not necessarily prevent light transmission to the pulp. Confocal microscopy demonstrated conduction of light within dystrophic deposits of irregular secondary dentine. CONCLUSIONS: The presence of carious lesions or restorations in molar teeth does not necessarily interfere with transmission of laser light to the pulp space. Light is conducted within irregular secondary dentine. With appropriate probe placement, assessments of pulp health in diseased posterior teeth may be possible using laser Doppler flowmetry.

Adult↗

PubMed1999

Laser Doppler flowmetry: an aid in differential diagnosis of apical radiolucencies.

The case of a patient having 2 teeth with associated apical radiolucencies that responded to conventional pulp tests is presented. A decision was made to reexamine the patient at intervals rather than perform root canal treatment. During a recall visit, use of an available laser Doppler flowmeter allowed detection of blood flow within the affected teeth. A diagnosis of periapical cemental dysplasia (cementoma) was made.

Adult↗

PubMed1999

Laser light transmission in teeth: a study of the patterns in different species.

AIM: 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. METHODOLOGY: 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. RESULTS: 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. CONCLUSION: 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.

Animals↗

PubMed1998

Rigidity and retention of root canal posts.

OBJECTIVE: To test the rigidity and the retention into roots of parallel root canal posts, one a spiral vented titanium post and the other a spiral serrated, hollow, stainless steel post. A serrated, stainless steel post was used as the control. MATERIALS AND METHODS: A three-point bending test was used to test rigidity. To test retention, ten posts of each type were cemented into the roots of extracted teeth with a resin cement and the tensile loads required to remove them were compared using Student's t and Mann-Whitney U tests. RESULTS: The serrated stainless steel posts were significantly more rigid than either of the other types. The titanium posts and the stainless steel hollow posts were not significantly different in rigidity. The serrated, stainless steel posts were significantly better retained than either of the other types. The titanium posts showed greater retention than the hollow posts. CONCLUSIONS: Within the limits of the study the stainless steel, serrated posts were superior to the two newer types in terms of rigidity and retention into roots.

Cementation↗