Laser light passage through restored and carious posterior teeth.

Laser Doppler flowmetry (LDF) has been used to investigate pulpal blood flow as a means of pulp vitality testing. Transmission of laser light from the tooth surface to the pulp space may be influenced by caries and restorations. One hundred and twenty-two first and second molars that had caries into dentine, restorations or significant loss of coronal tissue were sectioned in half axio-bucco-lingually. The two sections were illuminated with a laser from their buccal and lingual aspects 2 mm coronal to the amelocemental junction. Light reaching the pulp space was recorded. Buccal and lingual illumination sites were equally effective for 67 teeth (55%). Buccal sites alone were effective for 35 teeth (29%), despite over one-third of these surfaces being restored or featuring enamel or dentine caries. A lingual position alone was effective for 20 teeth (16%). Caries affected light transmission, but for over half the teeth, the pulp could be illuminated from all four probe positions. No effect was found when the influence of mesial and distal restorations on transmission into the corresponding tooth section was examined. The pulp spaces of most (84%) restored, and carious posterior teeth could be illuminated by laser light from their buccal aspect and these teeth could potentially be vitality tested using LDF.

Factors associated with pain induced by orthodontic separators.

Pain resulting from the application of orthodontic forces varies markedly across individuals. The reasons of this variability are still largely unknown. To investigate factors that may be associated with orthodontic pain following the application of orthodontic separators. One hundred and seven participants were screened for pain response over 48 h following placement of orthodontic elastomeric separators. The highest (n = 10) and lowest (n = 10) pain responders were identified, and data collected on tooth pain sensitivity to electrical stimulation in conjunction with using the Pain Catastrophising Scale (PCS), Dental Anxiety Scale (DAS) and cold pressor test (CPT). There were statistically significant differences between high- and low-pain responders in catastrophising score (P ≤ 0.023). For every PCS magnification score of 1 unit higher, the relative risk of being a high-pain responder was 1.6 (P = 0.002); those scoring higher on helplessness had a lower risk of being so. DAS scores of high-pain responders were twice as high as those of low-pain responder (P = 0.043). During the first 2 min of CPT, the high-pain responders experienced more pain than the low-pain responders (P ≤ 0.029). Tooth pain thresholds did not differ between the two different pain responder groups. Pain catastrophising, dental anxiety and cold sensitivity appear to modify the pain experienced following placement of orthodontic separators. Further research is needed to determine the validity of screening questions to identify at-risk patients prior to commencing orthodontic treatment.

Determination of working length for teeth with wide or immature apices: a review.

Practitioners face several challenges during the root canal treatment of teeth with wide or immature apices, one of which is working length determination. There is relatively little data regarding the value of radiography and electronic apex locator (EAL) use when root formation is incomplete, and supplementary measurement techniques may be helpful. This review considers length determination for canals with wide or completely open apices in permanent and primary teeth. The Ovid Medline, Web of Science and Scopus databases were searched individually and in combinations to August 2012 using the subject headings 'working length determination' and 'open apex' and revealed only one article. Further headings, 'tooth apex', 'apical constriction', 'resorption', 'foramen size', 'mature root apex', 'immature root apex', 'working length determination', 'apexification', 'open apices', 'open apex', 'open apical foramina', 'canal length determination', 'immature teeth', 'apical diameters', 'electronic apex locators', 'primary teeth', 'treatment outcome' and 'clinical outcome' were entered. Potentially useful articles were chosen for a manual search of bibliography as well as a forward search of citations. Other investigations revealed case reports and some research related to open apices and laboratory studies evaluating EALs, radiography and tactile methods. Some involved permanent teeth of various apical diameters and primary teeth with and without resorption. There is a need to define the term 'open apex'. Clinicians should be aware of the benefits and limitations of all canal measuring techniques involved in managing this problem.

Influence of clinical experience on the radiographic determination of endodontic working length.

AIM: To determine the influence of clinical experience on the accuracy and consistency of estimation of radiographic working length (WL) for the root canal treatment of single-rooted teeth. METHODOLOGY: Forty conventional WL periapical radiographs that included variations in file length were selected. They were digitally scanned and arranged in PowerPoint presentations on CDs. These were distributed to three assessor groups; fourth-year undergraduates at two stages of training (Groups 1 and 2) and endodontic postgraduates (Group 3). Participants were asked to determine the adjustment needed in millimetres to position the file tip at the correct WL for each image. A gold standard file position was provided by three experienced endodontists. For inter-group comparison of scores, the Kruskal-Wallis, ANOVA and post hoc Bonferroni tests were used. Evaluation of intra-examiner consistency was with the Kappa test. To evaluate intra-group consistency, the Wilcoxon signed rank test was used to compare the frequency of weighted correct scorings. RESULTS: File adjustments of Group 3 were significantly more accurate than those of Group 1 (P = 0.006). The scores of Group 3 were also better than those of Group 2, although the difference was not significant. When the scores of the undergraduate groups were compared, the difference was not statistically significant. The consistency of the groups was not affected by a 2-week pause between assessments, and no definite pattern could be detected across any of the groups with the Kappa test. CONCLUSION: Clinical experience after graduation influenced the accuracy of estimating the adjustments needed for correct radiographic WL of single-rooted teeth. The most experienced group was significantly more accurate than the other groups.

The smear layer in endodontics - a review.

Root canal instrumentation produces a layer of organic and inorganic material called the smear layer that may also contain bacteria and their by-products. It can prevent the penetration of intracanal medicaments into dentinal tubules and influence the adaptation of filling materials to canal walls. This article provides an overview of the smear layer, focusing on its relevance to endodontics. The PubMed database was used initially; the reference list for smear layer featured 1277 articles, and for both smear layer dentine and smear layer root canal revealed 1455 publications. Smear layer endodontics disclosed 408 papers. A forward search was undertaken on selected articles and using some author names. Potentially relevant material was also sought in contemporary endodontic texts, whilst older books revealed historic information and primary research not found electronically, such that this paper does not represent a 'classical' review. Data obtained suggests that smear layer removal should enhance canal disinfection. Current methods of smear removal include chemical, ultrasonic and laser techniques - none of which are totally effective throughout the length of all canals or are universally accepted. If smear is to be removed, the method of choice seems to be the alternate use of ethylenediaminetetraacetic acid and sodium hypochlorite solutions. Conflict remains regarding the removal of the smear layer before filling root canals, with investigations required to determine the role of the smear layer in the outcomes of root canal treatment.

Effect of restorations on pulpal blood flow in molars measured by laser Doppler flowmetry.

AIM: To: (i) compare laser Doppler pulpal blood flow (PBF) signals from restored and unrestored first molar teeth, (ii) investigate PBF in teeth with large and small restorations, and (iii) to relate PBF to pulp chamber dimensions on radiographs. METHODOLOGY: Bitewing radiographs of young adults with restored first molars were obtained and pulp chamber dimensions measured. Subjects were divided into 2 groups: group A with a restored tooth and an unrestored contralateral (43 subjects) and group B, those with a molar with a small (usually occlusal) restoration whilst the contralateral tooth had an extensive occlusal restoration (or restorations) or restored proximal surface(s) and/or cuspal overlay (31 subjects). The 148 teeth responded to electric pulp testing, and their PBF was recorded using a laser Doppler flowmeter. Data were analysed using Student's t-test. RESULTS: In group A the PBF in the restored teeth was significantly lower than in unrestored contralaterals (P = 0.028) and the total pulp chamber area and that in the clinical crown were smaller (P = 0.039 and 0.021 respectively). The group B molars with large restorations had significantly lower PBF than contralaterals with small restorations (P = 0.001), and their total pulp chamber area and pulp chamber width at cervix were reduced significantly (P = 0.003 and 0.032 respectively). CONCLUSIONS: In molars the size of the pulp chamber was influenced by the presence of restorations and the PBF was reduced when restorations were present. Size and extent of restorations had a significant effect on PBF.

Electric pulp testing: a review.

Electric pulp testing (EPT) has been available for more than a century and used in dental practices worldwide. This article provides an overview of this diagnostic aid. The PubMed database from 1953 was used initially; the reference list for pulp testing featured 1071 articles, and for EPT identified 121 papers. A forward search was undertaken on these articles and using selected author names. Potentially relevant material was also sought in contemporary endodontic texts, while older textbooks on endodontics, operative dentistry and pain revealed historic information and primary research not found electronically. A short account of the innervation of the pulp is followed by an historic overview. Clinical considerations discussed include tooth isolation, glove wearing and tester electrode placement. Orthodontic treatment, pacemaker wearing and patient medications are considered. Research applications are also discussed. While EPT is valuable, no single pulp testing technique can reliably diagnose all pulp conditions. Careful collection of patient history regarding the problem tooth and prudent use of appropriate radiographs are also helpful. The shortcomings of electric tests, especially in the case of immature and concussed teeth, must be understood. The demeanour of the patient and the responses given by control teeth also require careful consideration.

Pulp stones: a review.

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 'pulp calcifications' and 'pulp stones'. 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.

The antimicrobial effect within dentinal tubules of four root canal sealers.

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.

Effect of endodontic instrument handle diameter on operator performance.

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.

Preparation of dental enamel for use in intraoral cariogenicity experiments.

Dental enamel of human or bovine origin finds use in human intraoral cariogenicity testing. Such material must be sterile, and this is commonly achieved using ethylene oxide. The choice of this gas as a means of sterilization in cariogenicity work was vindicated when it failed in experiments to produce significant changes in the hardness of bovine enamel specimens. The gas is, however, shortly to become unavailable on environmental grounds. Alternatives investigated include autoclaving and gamma irradiation. Autoclaving produced significant softening of bovine enamel, the changes in microhardness recorded being similar to those produced by some experimental cariogenic substrates. Gamma irradiation caused no significant changes in enamel hardness. Recent in vitro work has, however, shown that enamel may gain resistance to artificial caries attack, and exhibit decreased acid solubility, following exposure to ionizing radiations. The results of experiments in which the test enamel was sterilized by this means may therefore lack comparability with experiments using an alternative sterilization method. However, with this qualification, gamma irradiation appears the most appropriate replacement for ethylene oxide.

Endodontic sequelae of miniplate bone fixation.

Various techniques of rigid internal fixation have evolved to achieve skeletal stability during healing. Although the miniplates and screws currently used have many advantages, their placement and presence may present significant difficulties for clinicians subsequently providing treatment. Problems with both endodontic diagnosis and treatment after miniplate fixation are illustrated with three case reports.

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.

Rigidity and retention of ceramic root canal posts.

Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended.

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.

Intra-oral softening of bovine enamel exposed to Lycasin and sucrose.

In previous experiments, the sucrose substitute Lycasin has been shown to possess low acidogenic potential. Intra-oral cariogenicity tests were carried out in humans to explore the enamel softening effects of Lycasin, using sucrose and saline as controls. The results confirmed that Lycasin would be preferred to sucrose as a sweetener for confections and medicines, although some softening of enamel by Lycasin was evident when compared to the saline controls. The magnitude of this enamel change was small and of doubtful clinical significance.

Assessment of the cariogenic potential of fruit fingers, muesli bars and jelly beans.

Intra-oral tests of a fruit bar, a muesli bar and jelly beans were performed to establish their cariogenic potential by means of enamel hardness changes. Little difference was found when the fruit finger and muesli bar were compared. Surprisingly, the jelly beans did not produce a greatly increased degree of softening when compared with the fruit fingers. Statistical significance was not reached in either of the experiments carried out.

Efficacy of three cavity liners in eliminating bacteria from infected dentinal tubules.

Three lining materials, Life, Ketac-Bond, and IRM, were investigated for their antibacterial effects within dentinal tubules. Sterile saline served as control. Sixty standardized bovine root specimens were infected with Enterococcus faecalis following smear layer removal. The materials were mixed according to manufacturer's directions and inserted in the canal lumina; additional IRM specimens received a softer than normal mix. Specimens were incubated for 24 hours or 7 days, after which dentinal samples were taken from within the lumina and the numbers of bacteria present were assessed. All the materials had a significant antibacterial effect after 7 days. Life demonstrated a more marked effect at 7 days than at 24 hours. The strongest antibacterial effect at 24 hours was shown by a "soft" mix of IRM. Ketac-Bond demonstrated an increase in antibacterial activity during the experimental period.

The radiographic assessment of pulp size: validity and clinical implications.

A study was performed to determine if the radiographic appearances of the coronal pulp spaces provide a reliable indication of pulp size in maxillary incisors. The use of student and staff assessor groups showed that length of clinical experience did not influence assessments of the size of the coronal pulp. A measuring grid, superimposed over a duplicate set of films, decreased the students' perception of the size of the coronal pulp. The presence of small carious lesions or restorations did not affect the assessments for either of the film types viewed. The data were pooled to give a mean radiographic size for each tooth, and the teeth were sectioned. Analysis of the results demonstrated the value of carefully viewing incisor crowns shown on pre-operative periapical radiographs. Sectioning of the teeth suggested that very little dentine may remain to protect the pulp after routine crown preparations. Even the very conservative preparations sometimes necessary when providing veneers might be considered a hazard to the pulp, as they may expose large areas of the dentine of an immature tooth.