Oral complications associated with metal ion release from oral piercings: a systematic review

PURPOSE

This systematic review explored dental complications associated with metal ion release from oral piercings using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

METHODS

Item retrieval from October 2022 to December 2022 from databases, such as Cochrane Central Register of Controlled Trials, Medline, PubMed, Embase, Scopus and Web of Science, using predefined search terms was undertaken by two independent reviewers. Data were extracted and risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. From 1509 identified studies, 25 were included for analysis.

RESULTS

Of the 25 studies, 20 included both clinical examination and questionnaire-based data. The remaining five studies were deemed low quality based on the Joanna Briggs Institute criteria. The average time piercings were worn ranged between 5 and 48 months. Most studies did not investigate complications from metal ion release. Only two studies examined the direct effects of metal ion release and showed that metal ions may cause hypersensitivity reactions and mucosal changes. Other soft tissue complications were reported, with gingival recession noted in 16 out of 25 studies, especially due to lip piercings. Studies reporting other complications were as follows: swelling (9), pain (8), infection (6), bleeding (6), inflammation (5), alterations to speech, eating and/or swallowing (5), changes to taste or metallic taste (5), and mucosal changes (4). Ten studies reported tooth chipping from tongue piercings.

CONCLUSION

Oral piercings leach metal ions into surrounding tissues which may cause local mucosal changes. Furthermore, oral piercings cause damage to both soft and hard oral tissues, particularly gingival recession for lip piercings and tooth chipping for tongue piercings. Thus, to prevent such adverse injuries, dental professionals should discourage patients against oral piercings.

Positive impacts of oral health services provision by a student-led primary care clinic to an Australian rural indigenous community

BACKGROUND

This study aimed to determine whether oral health services provision by a dental student clinical outplacement embedded within a Community Controlled Health Service positively impacted a rural Indigenous community and to explore the nature of these benefits.

METHODS

Aggregated and de-identified 2017, 2018 and 2019 student-led clinic services provision data were retrospectively analysed. The change in services mix over time was measured. Rural outplacement clinic operational costs to the university were estimated. Government-funded local public dental clinic waiting list and services provision data were used to identify any student clinic establishment effect.

RESULTS

The student-led clinic services mix shifted over time from mainly acute care for toothache towards prevention of disease and tooth restoration, indicating an improvement in patient oral health and correspondingly reduced system costs. Imputed value of 2017-2019 student-led clinic services provision totalled almost AUD$1 million. Government public clinic waiting list times decreased after full establishment of the student-led clinic, indicating decreased pressure on the public system.

CONCLUSION

The Community Controlled Health Service and university partnership improved community oral health care access, its timely delivery and simultaneously provided valuable human capital development from the student training experience. The student-led clinic's targeted Indigenous community showed oral health improvement over time. © 2023 Australian Dental Association.

Ion release from oral piercings from in vitro acidic challenges

OBJECTIVES

This laboratory-based study measured ion release from metallic piercings when exposed to organic acids (lactic, citric) and inorganic acids (phosphoric, hydrochloric) that could be encountered in the oral cavity.

METHODS

Barbell and ring oral piercings composed of stainless steel, titanium or gold-plated titanium were submerged in 2 mL volumes of 0.1% lactic acid, 10% citric acid, 0.2% phosphoric acid, and 0.1% hydrochloric acid for 7 and 34 days. Ion release into the liquid was measured using inductively coupled plasma optical emission spectroscopy (ICPOES) and expressed in relationship to surface area. Surface changes from baseline were assessed using light and backscatter scanning electron microscopy (SEM).

RESULTS

ICPOES results showed that hydrochloric and phosphoric acid caused the greatest release of material per surface area. Released elements included (ranked highest to lowest): Fe, P, Ti, Na, Cr, S, Ni, Ca, Mg, K, Si, Al, V, Mn, Ba, and Co. SEM imaging identified qualitative surface changes consistent with corrosion, for most piercing types examined.

CONCLUSIONS

Under the exposure conditions used, inorganic acids cause greater metal dissolution than organic acids. Inorganic acids could therefore pose a risk of corrosion and leaching of ions from metallic oral piercings.

Decontamination practices of paediatric crowns: a systematic review

Purpose

A systematic review was conducted into paediatric crown decontamination practices using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Method

After database retrieval using predefined search terms, two reviewers independently applied the selection criteria, extracted the data, and assessed for risk of bias. From 92 potentially eligible studies, 10 were included for analysis.

Results

Steam sterilisation (autoclaving) was used as the gold standard for reducing biological contaminants on paediatric crowns across in vivo studies. However, autoclaving was associated with microstructural changes such as crazing and contour alterations. Furthermore, several tooth coloured crowns were liable to undergo colour changes from steam sterilisation.

Conclusion

Ambiguous manufacturer guidelines on protocols for reprocessing and reuse after biological exposure raises concerns regarding cross contamination and leaves practitioners open to potential litigation. A better understanding of the compatibility of paediatric crowns and decontamination practices is needed. More research into alternative chairside technologies that use low temperature, such as hydrogen peroxide gas plasma sterilisation, is warranted.

Pulmonary arterial hypertension in hereditary hemorrhagic telangiectasia associated with ACVRL1 mutation: a case report

INTRODUCTION

Hereditary hemorrhagic telangiectasia is an autosomal dominant condition with an estimated prevalence of 1 in 5000. It is characterized by the presence of abnormalities of vascular structures, and may affect many organ systems, including the lungs, brain, spinal cord, gastrointestinal tract, and liver. A causative mutation is identified in approximately 97% of patients with definite hereditary hemorrhagic telangiectasia in one of three genes including a mutation in endoglin, a mutation in a locus mapped to chromosome 5, and an activin receptor-like kinase-1 (ACVRL1) mutation that is associated with an increased incidence of primary pulmonary hypertension. Pulmonary arterial hypertension is a rare (15-25 cases per million people) but severe vascular disorder. Heritable pulmonary arterial hypertension is associated with several gene mutations, with 75% having a mutation in the bone morphogenetic protein receptor 2 (BMPR2). However, the remaining 25% of patients have other associated genetic mutations including ACVLR1, which is also associated with hereditary hemorrhagic telangiectasia. Pulmonary arterial hypertension is a rare complication in patients with hereditary hemorrhagic telangiectasia (< 1% of the hereditary hemorrhagic telangiectasia population). We describe a case report with this rare occurrence.

CASE PRESENTATION

A 70-year-old white/caucasian Irish male presented for screening for hereditary hemorrhagic telangiectasia due to a history of recurrent epistaxis (once/week) and a family history suggestive of pulmonary hypertension. Genetic testing confirmed an ACVRL1 mutation, while an echocardiogram and right heart catheterization confirmed pulmonary arterial hypertension. On examination, he had several mucocutaneous telangiectasia across his face. He was commenced on tadalafil and macitentan. However, this led to increased iron deficiency anemia and pedal edema. Selexipag was also added to his drug regime. He continues to require intermittent admissions for diuresis and blood transfusions.

CONCLUSION

The association of hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension is rare (< 1%). Here we describe a case of hereditary hemorrhagic telangiectasia complicated with pulmonary arterial hypertension as a result of an ACVRL1 mutation. We also describe the clinical challenges of treating these two conditions together, as treatment options for pulmonary arterial hypertension tend to worsen hereditary hemorrhagic telangiectasia symptoms.

Trends in Australian dental prescribing of antibiotics: 2005-2016

BACKGROUND

Prescribing of antibiotics by dentists for surgical prophylaxis or as an adjunct to managing dental infections is a substantial part of the overall landscape for prescribed antibiotics in health care settings.

METHODS

We explored trends in the antibiotic prescribing patterns of Australian dentists over the 12-year period, 2005-2016. We obtained data on dispensed prescriptions of antibiotics from registered dentists subsidized on the Pharmaceutical Benefits Scheme.

RESULTS

Australian dentists were responsible for almost 7 million dispensed prescriptions of antibiotics over 12 years; an average of 24 prescriptions per year per dentist. The most commonly prescribed antibiotic was amoxicillin, followed by amoxicillin + clavulanic acid and metronidazole. These top three antibiotics constituted more than 80% of all antibiotics prescribed and their use increased dramatically over time. There was a large increase in the prescribing of broad-spectrum antibiotics over time, most of which occurred from 2011 to 2016.

CONCLUSIONS

Excessive prescribing of broad-spectrum antibiotics runs contrary to national antimicrobial stewardship (AMS) initiatives and guidelines. Multifaceted educational strategies are essential to align prescribing with current best practice. High-level evidence to inform clear guidelines on antibiotic prescribing in dental infections, with audit and feedback, should reduce the inappropriate use of antibiotics in dentistry.

The Queensland Birth Cohort Study for Early Childhood Caries: Results at 7 Years

AIMS

This study investigated caries predictors in 378 children remaining from a birth cohort of 1,052 at 7 y and compared the efficacy of home visits (HVs) and telephone contacts (TCs) for early childhood caries (ECC) prevention.

METHODS

The HVs or TCs were made at ages 6, 12, 18, 30, and 42 mo with annual dental clinic examinations at ages 2 to 7 y. At every visit, the parents completed validated questionnaires regarding the children's family, medical, dental, and dietary histories.

RESULTS

The caries prevalence increased from 2% and 6% at ages 2 and 3 y to 15%, 33%, 42%, and 52% at ages 4 to 7 y. The mean caries experience (decayed, missing, and teeth extracted due to caries) of the total cohort increased from 0.1 ± 0.5 at age 2 y to 0.2 ± 1.1 at 3 y, 0.5 ± 1.6 at 4 y, 1.1 ± 2.4 at 5 y, 1.6 ± 2.6 at 6 y, and 2.0 ± 2.7 at 7 y. The prevalence of mutans streptococci (MS) in the total cohort at years 2 to 7 was 22%, 36%, 42%, 42%, 39%, and 44%, respectively. MS was strongly correlated with caries prevalence for all years (all P < 0.001). Statistical modeling employing the generalized estimating equations identified caries predictors as holding a Health Care Card (low socioeconomic status) (P = 0.009; odds ratio [OR] = 2.05; confidence interval [CI]: 1.20-3.52), developmental defects of enamel (DDEs) (P < 0.001; OR = 1.09; CI: 1.05-1.14), and MS counts ≤10⁵/mL (P = 0.001; OR = 1.63; CI: 1.24-2.14). By contrast, HVs were more protective than TCs for caries (P = 0.008; OR = 0.42; CI: 0.22-0.80).

CONCLUSIONS

This study provides prospective, clinical evidence that MS, DDEs, and low socioeconomic status are strongly correlated with early childhood caries and that HVs are more efficacious than TCs in ECC prevention.

KNOWLEDGE TRANSFER STATEMENT

This 7-y birth cohort study provides longitudinal clinical evidence that mutans streptococci, developmental defects of enamel, and low socioeconomic status are key risk indicators of early childhood caries.

Prevention and caries risk management in teenage and orthodontic patients

As patients progress from childhood through to teenage years, they progress through periods of high caries risk as they undergo changes in lifestyle and oral microflora. Removable or fixed orthodontic treatment also alters the oral microflora and can dramatically increase caries risk. This paper outlines ways to identify the transition to higher caries risk, and practical ways to lower the risk of hard tissue loss from dental caries during orthodontic treatment across the teenage years, including tooth surface protection, optimised use of mechanical and chemical plaque control, and appropriate delivery of remineralising agents over time.

Randomized Controlled Study to Evaluate Microbial Ecological Effects of CPP-ACP and Cranberry on Dental Plaque

INTRODUCTION

Ecological approaches to dental caries prevention play a key role in attaining long-term control over the disease and maintaining a symbiotic oral microbiome.

OBJECTIVES

This study aimed to investigate the microbial ecological effects of 2 interventional dentifrices: a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) dentifrice and the same dentifrice supplemented with a polyphenol-rich cranberry extract.

METHODS

The interventional toothpastes were compared with each other and with an active control fluoride dentifrice in a double-blinded randomized controlled trial. Real-time quantitative polymerase chain reaction (qPCR) analysis was used to determine changes in the bacterial loads of 14 key bacterial species (8 caries associated and 6 health associated) in the dental plaque of trial participants after they used the dentifrices for 5 to 6 wk.

RESULTS

From the baseline to the recall visit, significant differences were observed between the treatment groups in the bacterial loads of 2 caries-associated bacterial species (Streptococcus mutans [P < 0.001] and Veillonella parvula [P < 0.001]) and 3 health-associated bacterial species (Corynebacterium durum [P = 0.008], Neisseria flavescens [P = 0.005], and Streptococcus sanguinis [P < 0.001]). Compared to the fluoride control dentifrice, the CPP-ACP dentifrice demonstrated significant differences for S. mutans (P = 0.032), C. durum (P = 0.007), and S. sanguinis (P < 0.001), while combination CPP-ACP-cranberry dentifrice showed significant differences for S. mutans (P < 0.001), V. parvula (P < 0.001), N. flavescens (P = 0.003), and S. sanguinis (P < 0.001). However, no significant differences were observed in the bacterial load comparisons between the CPP-ACP and combination dentifrices for any of the targeted bacterial species (P > 0.05).

CONCLUSIONS

Overall, the results indicate that dentifrices containing CPP-ACP and polyphenol-rich cranberry extracts can influence a species-level shift in the ecology of the oral microbiome, resulting in a microbial community less associated with dental caries (Australian New Zealand Clinical Trial Registry ANZCTR 12618000095268).

KNOWLEDGE TRANSFER STATEMENT

The results of this randomized controlled trial indicate that dentifrices containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and polyphenol-rich cranberry extracts were able to beneficially modulate the microbial ecology of dental plaque in a group of high caries-risk patients. This could contribute toward lowering the risk of developing new caries lesions, an important goal sought by patients, clinicians, and policy makers.

Violet and blue light-induced green fluorescence emissions from dental caries

BACKGROUND

The objective of this laboratory study was to compare violet and visible blue LED light-elicited green fluorescence emissions from enamel and dentine in healthy or carious states.

METHODS

Microscopic digital photography was undertaken using violet and blue LED illumination (405 nm and 455 nm wavelengths) of tooth surfaces, which were photographed through a custom-made stack of green compensating filters which removed the excitation light and allowed green fluorescence emissions to pass. Green channel pixel data were analysed.

RESULTS

Dry sound enamel and sound root surfaces showed strong green fluorescence when excited by violet or blue lights. Regions of cavitated dental caries gave lower green fluorescence, and this was similar whether the dentine in the lesions was the same colour as normal dentine or was darkly coloured. The presence of saliva on the surface did not significantly change the green fluorescence, while the presence of blood diluted in saliva depressed green fluorescence.

CONCLUSIONS

Using violet or blue illumination in combination with green compensating filters could potentially aid in the assessment of areas of mineral loss.

Is there a consensus on antibiotic usage for dental implant placement in healthy patients?

This systematic review aimed to determine whether there is consensus for antibiotic prescription in healthy patients undergoing implant placement. A search of PubMed, Embase and Medline databases was conducted in January 2016 to find published journal articles on the use of antibiotics in implant placement, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The inclusion criteria were prospective human clinical trials investigating antibiotic usage during implant placement. Fifteen studies were deemed suitable. In 13 studies, no statistical difference was found between antibiotic use and the incidence of prosthetic failure, implant failure and early postoperative infections. These were rated as having low to high risk bias. Contrary results were reported in two studies, both of which were rated as having a high potential for bias. In conclusion, antibiotic use in healthy patients for the prophylaxis of surgical infection associated with dental implant placement does not appear to improve clinical outcomes. Practitioners should apply principles of antimicrobial stewardship and not use antibiotics as a routine measure in healthy patients.

Antibacterial activity of fluoride compounds and herbal toothpastes on Streptococcus mutans: an in vitro study

BACKGROUND

Streptococcus mutans is an important bacterial species implicated in dental caries. This laboratory study compared the antimicrobial activity of a number of fluoride containing and herbal dentifrices and their components against S. mutans.

METHODS

An agar diffusion method was used with Mueller-Hinton agar. Wells were filled with either 10 commercial fluoride or 6 herbal dentifrices, or with solutions of various fluoride compounds, sodium lauryl sulphate, sodium benzoate, chlorhexidine digluconate or triclosan. Diameters of zones of bacterial growth inhibition surrounding the wells were measured using a micrometer.

RESULTS

Significant differences were found for growth inhibition between the 10 fluoridated dentifrices (p < 0.0001), with Colgate Total having the greatest effect. There was not a direct correlation with fluoride type or fluoride concentration. The antibacterial activities of the 6 herbal toothpastes varied, with Herbal Fresh being the strongest. Sodium lauryl sulphate showed strong antimicrobial activity against S. mutans at the levels used in dentifrices.

CONCLUSIONS

Antimicrobial activity of commercial dentifrices against S. mutans may be exerted by components other than fluoride. Ingredients such as triclosan and sodium lauryl sulphate have larger antimicrobial effects than fluorides in this model.

Evaluation and prevention of enamel surface damage during dental restorative procedures

BACKGROUND

This study examined the effect of operator experience, dominance, tooth position and access, on frequency and extent of iatrogenic damage to approximal tooth surfaces during conventional Class II cavity preparations. The effectiveness of protective devices in minimizing damage was also explored.

METHODS

10 students and 10 experienced dentists each prepared 24 Class II cavity preparations in typodont teeth without protection; 10 utilizing stainless steel matrix bands and 10 utilizing protective wedges. The frequency and extent of damage were analysed with respect to the above variables. Subsequently, 20 natural and 20 typodont teeth were utilized to establish the relationship in depth of damage caused by a high-speed diamond bur on typodont versus natural teeth.

RESULTS

Dentists caused iatrogenic damage on 74% of approximal surfaces without protection, which fell to 50% and 46% respectively when matrix bands and wedges were used as guards. The corresponding rates of damage for students were 94%, 80% and 44%. There was no difference in depth of damage caused on the two types of teeth when bur was in contact with teeth for a very short time.

CONCLUSIONS

Greater operator experience and the use of guards reduces iatrogenic damage to proximal surfaces during preparation with high-speed rotary instruments.

Factors affecting the rate of oxidation and resultant discolouration of tetracyclines contained in endodontic medicaments and irrigants

AIM

To determine the effect of pH, oxygen levels and ions on tetracycline oxidation and resultant discolouration.

METHODOLOGY

Solutions of demeclocycline hydrochloride or doxycycline hyclate were prepared and exposed to different pH conditions, pure oxygen or carbon dioxide, ascorbic acid or various ions (from calcium chloride, calcium nitrate, strontium chloride, magnesium chloride, zinc chloride, and bismuth nitrate). Subsequently, they were exposed to intense visible blue light (470 ± 15 nm) for 24 h. Colour change was monitored using standardized digital photography. Parametric statistical analysis employing the Wilcoxon matched-pairs signed-rank test was performed to compare the mean change in different colour channels, assessing the discolouration effect of the modified conditions.

RESULTS

An acidic pH reduced discolouration, whilst alkaline pH increased it. A higher oxygen tension resulted in more discolouration, as did the presence of calcium, strontium, and bismuth ions, all of which bind to tetracyclines. Conversely, zinc and magnesium ions had a mild photoprotective effect. Ascorbic acid, an anti-oxidant, reduced the level of discolouration.

CONCLUSIONS

The tendency of these tetracyclines to undergo photo-oxidation is increased by common variables present in the clinical environment. There are potential benefits from using photoprotectors and anti-oxidants in these materials, to reduce the possibility of discolouration.

Minimal intervention dentistry in general practice

Minimal Intervention Dentistry (MID) is a modern approach to the management of caries, which emphasizes prevention and early interception of disease, underpinned by an understanding of the role of the dental plaque biofilm in disease initiation and progression, and how this is affected by lifestyle and behavioral factors. The MID approach should be the standard of care in modern restorative dentistry, as it avoids over-zealous restorative interventions as well as supervised neglect. Incorporating the principles of MID into general dental practice for the management of dental caries involves using Caries Risk Assessment (CRA), as well as a minimally invasive restorative approach utilizing conservative caries removal methods, minimal cavity designs and the use of adhesive restorative materials. A range of methods now exist for measuring the contribution of risk factors to dental caries risk, allowing the clinician to target their interventions at the factors operating in the individual patient, by applying the concepts of ecological change to modify the biofilm, and motivational interviewing to alter patient lifestyle and dietary behaviour. This review discusses how the principles of MID are used for individual patient care, and suggests methods for implementation of MID into general dental practice.

Randomized controlled trial: a randomized controlled clinical trial comparing a remineralizing paste with an antibacterial gel to prevent early childhood caries

PURPOSE

The purpose of this study was to compare twice daily tooth-brushing using 0.304 percent fluoride toothpaste alone with: (1) twice daily tooth-brushing plus once daily 10% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste; and (2) twice daily tooth-brushing plus once daily 0.12% chlorhexidine gel (CHX) for reducing early childhood caries (ECC) and mutans streptococci (MS) colonization.

METHODS

Subjects (n=622) recruited at birth were randomized to receive either CPP-ACP or CHX or no product (study control [SC]). All children were examined at 6, 12, and 18 months old in their homes, and at 24 months old in a community dental clinic.

RESULTS

At 24 months old, the caries incidence was 1% (2/163) in CPP-ACP, 2% (4/180) in CHX, and 2% (3/188) in SC groups. In children who were previously MS colonized at 12 and 18 months old, 0% (0/11) and 5% (3/63), respectively, of the CPP-ACP group remained MS-positive versus 22% (2/9) and 72% (18/25) in CHX and 16% (4/25) and 50% (7/14) in SC groups (P<.001).

CONCLUSIONS

There is insufficient evidence to justify the daily use of casein phosphopeptide-amorphous calcium phosphate or chlorhexidine gel to control early childhood caries.

A longitudinal study comparing mutans streptococci and lactobacilli colonisation in dentate children aged 6 to 24 months

This longitudinal study aimed to investigate variables associated with colonisation of mutans streptococci (MS) compared with lactobacilli (LB) colonisation in a cohort of children (n = 214) from the time of first tooth eruption at approximately 6 months until 24 months of age. Repeated plaque and salivary samples were collected from the same infants at 6, 12, 18 and 24 months and assayed for MS and LB using a microbiological culture kit. Children having both MS and LB increased from 4% at 6 months to 13% at 12 and 18 months to 20% at 24 months (p = 0.004). LB presence at 6 months was correlated with MS presence at 12, 18 and 24 months (r = 0.21 to r = 0.46, p = 0.02), while MS presence at 6 months correlated with LB presence at all other times (r = 0.19 to r = 0.31, p = 0.03). At 6 and 12 months, the key variables for MS colonisation included unrestored dental cavities in the mother (p = 0.03), mother not persisting with toothbrushing (p = 0.001) and bottle taken to bed at night (p = 0.033), while the only significant variable for LB colonisation was natural birth (p = 0.01). At 24 months, the significant variables for MS colonisation were condiments added to pacifier (p = 0.022) and child being uncooperative for toothbrushing (p = 0.025), while the significant variables for LB colonisation were pregnancy problems (p = 0.028) and child being uncooperative for toothbrushing (p = 0.013). The ages 6-12 months thus represent a time period when key variables may be controlled to reduce MS and LB colonisation.

Clinical assessment and management of the oral environment in the oncology patient

The dental care of oncology patients is an important component of general dental practice. Oncology patients have additional requirements for their outpatient care in the dental office. Intense involvement of the general dental practitioner in the patient's overall plan of care is essential so that appropriate preventive and therapeutic strategies are followed prior to chemotherapy, radiation and other medical treatments. This paper provides an overview of the role of the dental practitioner in the pre-treatment workup and post-treatment maintenance of oncology patients, and discusses the complications which occur during the intensive and in-hospital phases of care, in the context of approaches that show promise for reducing or preventing these. The role of the general dental practitioner in the maintenance of oral health for the remainder of the patient's life is stressed, with evidence-based recommendations given for optimal use of home care products which support oral health and improve quality-of-life.

In vitro study of the inactivation by dentine of some endodontic medicaments and their bases

BACKGROUND

The aim of this study was to investigate the antimicrobial effect of endodontic medicaments and their bases in the presence of dentine powder.

METHODS

The medicaments tested were Ledermix paste, Pulpdent paste, a 50:50 combination of the Pulpdent:Ledermix and their bases. The test organism was Enterococcus faecalis ATCC 29212. The presence or absence of dentine was examined as well as the effect of autoclaving dentine. Serial dilutions of samples at 1 hour, 1 day and 3 days were used for colony counting. The effects of dentine powder on pH for saturated Ca(OH)2 solution and Pulpdent paste at 1 hour and 24 hours were also measured.

RESULTS

Pulpdent and the 50:50 combination of Pulpdent:Ledermix completely inhibited the growth of E. faecalis from 1 hour onwards, and these results were not affected by the presence/absence of dentine powder, pre-incubation period, timing of autoclaving, or exposure time. Saturated solutions of Ca(OH)2 are prone to inactivation by dentine powder unlike Pulpdent paste. Ledermix paste took 3 days to exert a significant effect on the growth of E. faecalis.

CONCLUSIONS

In this laboratory study, both Pulpdent and the 50:50 mixture of Pulpdent with Ledermix were effective medicaments against E. faecalis in the presence of dentine powder.

Oral health students' perceptions of clinical reflective learning--relevance to their development as evolving professionals

CONTEXT

A clinical professional should be a reflective practitioner, however reflective learning and deliberate clinical reflections have not traditionally featured in dentistry or dental hygiene programs. To the authors' knowledge, there are no studies exploring the perceptions of oral health students to reflective learning and clinical reflective practices.

AIM

This study determined student perceptions of clinical reflective learning and its relevance to their clinical and professional development.

METHODS

Reflective learning was embedded as a topic in the curriculum of the University of Queensland Bachelor of Oral Health program, within the discipline of dental hygiene practice. Reflective practices were integrated with clinical practice, and were linked with assessment requirements. Students' perceptions of clinical reflective learning were obtained via quantitative and qualitative analyses of sequenced questionnaires. Computer-assisted thematic analyses of the students' reflective journals, reflective essays and summary notes from in-class group discussions validated students' perceptions.

RESULTS

Students (n = 17) perceived clinical reflective learning as relevant, and useful for consolidating their clinical learning and accelerating their professional development. In particular, students gained insights about their strengths and weaknesses, thought more deeply about what they were doing in the clinic, and unpacked difficult concepts.

CONCLUSION

Students views of clinical reflective learning in this program were positive. They believed that the deliberate reflective process assisted their clinical learning and professional development.

Laser-activated fluoride treatment of enamel as prevention against erosion

BACKGROUND

Erosion is the loss of dental hard tissues from an acidic challenge, often resulting in exposure of dentinal tubules and hypersensitivity to environmental stimuli. Laser-activated fluoride (LAF) therapy with 488nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution. The aims of this study were to investigate the action spectrum of LAF in protecting tooth enamel from softening in response to an erosive challenge, and to examine for any temperature change with the treatment.

MATERIALS AND METHODS

Buccal and lingual surfaces of extracted sound molar and premolar teeth were used to prepare matched pairs of enamel slabs (N = 10 per group). After application of 1.23% neutral sodium fluoride gel (12 300ppm F ion), slab surfaces were lased with 488, 514.5, 532, 633, 670, 830 or 1064nm wavelength (energy density 15J/cm(-2); spot size 5mm), then exposed to an erosive challenge (1.0M HCI for five minutes). The Vicker's hardness number (VHN) was recorded before fluoride gel application and again following the acid challenge. Negative controls did not receive laser exposure.

RESULTS

All wavelengths of laser light examined provided a protective LAF effect against softening, compared with the negative control surfaces.

CONCLUSION

From these findings, we conclude that the action spectrum of the LAF effect extends across the visible spectrum, providing protection to dental enamel from an erosive challenge.

Laser-activated fluoride treatment of enamel against an artificial caries challenge: comparison of five wavelengths

BACKGROUND

Laser-activated fluoride (LAF) therapy with 488 nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution in laboratory models of dental caries. The aims of this study were to examine whether LAF therapy, conducted using a range of wavelengths in the visible and near infrared regions, can protect human dental enamel from an artificial cariogenic challenge.

MATERIALS AND METHODS

Buccal and lingual surfaces of extracted sound, molar and premolar teeth were used to prepare matched pairs of enamel slabs (N=10 per group). After application of neutral sodium fluoride gel (12300 ppm F ion), slab surfaces were lased (energy density 15 J/cm2; spot size 5mm, wavelength 532, 633, 670, 830 or 1064nm), then exposed to an artificial cariogenic challenge for a period of seven days. The Vicker's hardness number (VHN) was recorded before and after laser treatment and again following the cariogenic challenge. Negative controls did not receive laser exposure.

RESULTS

All wavelengths of laser light examined provided an effective LAF effect, compared with the unlased negative control surfaces.

CONCLUSION

Using this in vitro model, we conclude that the action spectrum of the LAF effect extends across the visible and near-infrared regions of the spectrum.

The use of calcium hydroxide, antibiotics and biocides as antimicrobial medicaments in endodontics

Bacteria have been implicated in the pathogenesis and progression of pulp and periapical diseases. The primary aim of endodontic treatment is to remove as many bacteria as possible from the root canal system and then to create an environment in which any remaining organisms cannot survive. This can only be achieved through the use of a combination of aseptic treatment techniques, chemomechanical preparation of the root canal, antimicrobial irrigating solutions and intracanal medicaments. The choice of which intracanal medicament to use is dependent on having an accurate diagnosis of the condition being treated, as well as a thorough knowledge of the type of organisms likely to be involved and their mechanisms of growth and survival. Since the disease is likely to have been caused by the presence of bacteria within the root canal, the use of an antimicrobial agent is essential. Many medicaments have been used in an attempt to achieve the above aims but no single preparation has been found to be completely predictable or effective. Commonly used medicaments include calcium hydroxide, antibiotics, non-phenolic biocides, phenolic biocides and iodine compounds. Each has advantages and disadvantages, and further research is required to determine which is best suited for root canal infections.

Temperature changes in dental pulp associated with use of power grinding equipment on equine teeth

OBJECTIVE

To quantify the temperature changes in the dental pulp associated with equine dental procedures using power grinding equipment.

DESIGN

A matrix experimental design with replication on the same sample was followed to allow the following independent variables to be assessed: horse age (young or old), tooth type (premolar or molar), powered grinding instrument (rotating disc or die grinder), grinding time (15 or 20 seconds) and the presence or absence of water coolant.

PROCEDURE

Sound premolar and molar teeth from a 6-year-old horse and a 15-year-old horse, which had been removed postmortem, were sectioned parallel to the occlusal plane to allow placement of a miniature thermocouple at the level of the dental pulp. The maximum temperature increase, the time taken to reach this maximum and the cooling time were measured (n=10 in each study). The teeth were placed in a vice and the instrument used on the tooth as per clinical situation.

RESULTS

Significant differences were recorded for horse age (P < 0.001), instrument type (P < 0.001), grinding time (P < 0.001) and presence or absence of coolant (P < 0.001). There was no significant difference for tooth type.

CONCLUSION

Thermal insult to the dental pulp from the use of power instruments poses a significant risk to the tooth. This risk can be reduced or eliminated by appropriate selection of treatment time and by the use of water irrigation as a coolant. The increased dentine thickness in older horses appears to mitigate against thermal injury from frictional heat.

Prostaglandin E2 enhances alveolar bone formation in the rat mandible

Prostaglandin E2 (PGE2) induces bone formation in stress-bearing bones. The mandible, a stress-bearing bone, is loaded daily during mastication. The aim of this study was to determine if PGE2 delivered locally to the mandible over 20 days enhances alveolar bone deposition. In 18 Lewis rats, controlled-release pellets containing PGE2 were implanted on the buccal aspect on the left-hand side of the mandible, mesial to the root of the first molar. Controlled-release pellets locally delivered 0.1, 0.05, or 0.025 mg/day of PGE2. The right side of the mandible was used as a matched control for each animal. Six sham-treated animals were implanted with a placebo pellet. On days 7 and 19, animals were injected with the bone markers tetracycline and calcein, respectively. On day 21, animals were sacrificed and undecalcified tissues obtained for morphometrical analysis. Morphometrical measurements were analyzed by paired t test to determine differences between the matched samples and one-way ANOVA to compare the different treatment groups. A significant increase in alveolar bone area was observed in mandibles treated with 0.1 and 0.05 mg/day when compared with matched controls and the placebo group. This was accompanied by a significant increase in alveolar bone height and width. The proportions of double-labeled surface (dLS), the mineral apposition rate (MAR), and bone formation rate (BFR) were significantly increased in mandibles treated with the two higher doses of PGE2. The proportion of resorptive surface (RS) was significantly reduced in these two groups. It is concluded that PGE2 induces alveolar bone formation in the mandible when locally delivered at a dose of 0.1 or 0.05 mg/day for 20 days.

The current status of laser applications in dentistry

A range of lasers is now available for use in dentistry. This paper summarizes key current and emerging applications for lasers in clinical practice. A major diagnostic application of low power lasers is the detection of caries, using fluorescence elicited from hydroxyapatite or from bacterial by-products. Laser fluorescence is an effective method for detecting and quantifying incipient occlusal and cervical carious lesions, and with further refinement could be used in the same manner for proximal lesions. Photoactivated dye techniques have been developed which use low power lasers to elicit a photochemical reaction. Photoactivated dye techniques can be used to disinfect root canals, periodontal pockets, cavity preparations and sites of peri-implantitis. Using similar principles, more powerful lasers can be used for photodynamic therapy in the treatment of malignancies of the oral mucosa. Laser-driven photochemical reactions can also be used for tooth whitening. In combination with fluoride, laser irradiation can improve the resistance of tooth structure to demineralization, and this application is of particular benefit for susceptible sites in high caries risk patients. Laser technology for caries removal, cavity preparation and soft tissue surgery is at a high state of refinement, having had several decades of development up to the present time. Used in conjunction with or as a replacement for traditional methods, it is expected that specific laser technologies will become an essential component of contemporary dental practice over the next decade.

A longitudinal study of Streptococcus mutans colonization in infants after tooth eruption

We previously reported that, before tooth eruption, over one-half of infants aged 6 mos were already infected with Streptococcus mutans. The aim of this investigation was to determine the colonization of S. mutans after tooth eruption in the same cohort of 111 infants (35 pre-term, 76 full-term). Our results showed that S. mutans colonization increased with increasing age, so that by 24 mos of age, 84% harbored the bacteria (p < 0.01). The mean and median ages of S. mutans colonization in dentate infants were 15.7 mos and 16.0 mos, respectively. Factors associated with S. mutans colonization were sweetened fluids taken to bed (p < 0.01), frequent sugar exposure (p < 0.03) and snacking (p < 0.03), sharing of foods with adults (p < 0.03), and maternal S. mutans levels of > 10(5) CFU/mL (p < 0.02). In contrast, non-colonization of S. mutans was associated with toothbrushing (p < 0.03) and multiple courses of antibiotics (p < 0.001). Analysis of our data establishes the timing of S. mutans colonization in children from birth to 24 mos of age.

The effects of chlorhexidine gel on Streptococcus mutans infection in 10-month-old infants: a longitudinal, placebo-controlled, double-blind trial

PURPOSE

This study investigated the long-term effects of 0.2% chlorhexidine gel, used as a weekly brush-on gel, on Streptoccocus mutans infection in 10-month-old infants.

METHODS

The investigation followed the criteria of a placebo-controlled, double-blind, longitudinal clinical trial. Infants were recruited at birth and oral microbiological swabs were taken at 3 monthly intervals, together with medical, dental, dietary and brushing histories. Children who were found to be colonized with S. mutans were randomly assigned to either the chlorhexidine-gel group (N = 50) or placebo gel group (N = 46), and parents were instructed to brush the gel on the teeth once per week for 12 weeks. In another control group (N = 210), infants did not use either chlorhexidine or placebo gels. Saliva samples were cultured using S. mutans-selective tryptone-yeast extract-cysteine-sucrose-bacitracin (TYCSB) agar. The mean age of the children was 10.2 +/- 2.6 months at the start of the trial and subjects were followed until the ages of 18 months.

RESULTS

In the children with initial low S. mutans counts of < 300 CFU/mL, there was a significant percentage reduction in S. mutans counts in the chlorhexidine-gel group compared to the placebo gel and no-gel control groups after 3 months of weekly gel brushing. However, no significant differences with the placebo group were observed after 15 months of follow-up. There were 39 children (41%) who achieved reduction of their S. mutans to 0 CFU/mL. Compared to those who remained infected with S. mutans, these children had higher toothbrushing frequencies (P < .001) and toothpaste use (P < .001), as well as lower frequencies of daily feeds (P < .01), and lesser weekly frequencies of sweet solids and liquids (P < .001).

CONCLUSIONS

Children with relatively low initial S. mutans counts (< 300 CFU/mL) showed a reduction in S. mutans counts in the first 3 months when 0.2% chlorhexidine gel was brushed on the teeth weekly. No differences were observed when compared with the placebo and no-treatment groups at later follow-up periods.

Immunoglobulins in saliva of preterm and full-term infants

The aim of this longitudinal study was to determine salivary levels of total IgA, IgG and IgM in 84 preterm and 214 full-term infants, from birth to 18 months of age. Unstimulated whole saliva was collected from each infant at birth, and subsequently at 3-monthly intervals. Immunoglobulin levels were estimated using an ELISA technique. At birth, IgA was detected in 147/214 (69%) full-term infants but only 47/84 (56%) preterm infants (P < 0.01). In the case of IgG, 61% of full-term and 56% of preterm infants showed detectable levels, whereas IgM was found in 71% and 73%, respectively. Levels of IgA and IgG rose from birth to 18 months, whereas IgM levels did not change significantly. Increases in salivary levels of IgA were associated with introduction of solid foods (P < 0.001), as well as tooth eruption (P < 0.001). Our results indicate that the majority of full-term and preterm infants are orally immunocompetent at birth.

Pulpal heat changes with newly developed resin photopolymerisation systems

Composite resin is a widely-used direct tooth coloured restorative material. Photoactivation of the polymerisation reaction can be achieved by visible blue light from a range of light sources, including halogen lamps, metal halide lamps, plasma arc lamps, and Light Emitting Diode (LED) lights. Concerns have been raised that curing lights may induce a temperature rise that could be detrimental to the vitality of the dental pulp during the act of photoactivation. The present study examined heat changes associated with standardised class V restorations on the buccal surface of extracted premolar teeth, using a curing time of 40 seconds. The independent effects of type of light source, resin shade, and remaining tooth thickness were assessed using a matrix experimental design. When a conventional halogen lamp, a metal halide lamp and two different LED lights were compared, it was found that both LED lamps elicited minimal thermal changes at the level of the dental pulp, whereas the halogen lamp induced greater changes, and the metal halide lamp caused the greatest thermal insult of all the light sources. These thermal changes were influenced by resin shade, with different patterns for LED versus halogen or halide sources. Thermal stress reduced as the remaining thickness of tooth structure between the pulp and the cavity floor increased. From these results, it is concluded that LED lights produce the least thermal insult during photopolymerisation of composite resins.

The pathogenesis of oral lichen planus

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

Mast cell/T cell interactions in oral lichen planus

Lichen planus is a disorder characterized by lesions of the skin and oral mucous membranes. Although many patients have involvement of both skin and oral mucosa at some stage during the progress of the disease, a larger group has oral involvement alone. It has been reported that oral lichen planus (OLP) affects one to two percent of the general population and has the potential for malignant transformation in some cases (1, 2). Like many chronic inflammatory skin diseases, it often persists for many years. Numerous disorders may be associated with OLP such as graft-vs.-host disease and Hepatitis C virus infection (3), however, it is unclear how such diverse influences elicit the disease and indeed whether they are identical to idiopathic OLP. Available evidence supports the view that OLP is a cell-mediated immunological response to an induced antigenic change in the mucosa (4-6). Studies of the immunopathogenesis of OLP aim to provide specific novel treatments as well as contributing to our understanding of other cell-mediated inflammatory diseases. In this paper, the interactions between mast cells and T cells are explored from the standpoint of immune regulation. From these data, a unifying hypothesis for the immunopathogenesis of OLP is then developed and presented.

Expression of RANTES and CCR1 in oral lichen planus and association with mast cell migration

BACKGROUND

T lymphocytes and mast cells infiltrate the lamina propria in oral lichen planus (OLP). Chemokines and their receptors are involved in T cell and mast cell migration and accumulation during the inflammatory process.

METHODS

In the present study, we investigated the role of RANTES and its receptors in OLP using immunohistochemistry, RT-PCR and an in vitro chemotaxis assay.

RESULTS

RANTES and CCR1 were expressed on T cells and mast cells in OLP, while OLP lesional T cell supernatants stimulated CCR1 mRNA expression in a human leukemia mast cell line (HMC-1). TNF-alpha stimulated CCR1, CCR4 and CCR5 mRNA expression in the same cell line. OLP lesional T cell supernatants stimulated HMC-1 migration, which was partly inhibited by anti-RANTES antibody.

CONCLUSIONS

The present study shows, for the first time, the distribution of RANTES and CCR1 in OLP. It is hypothesized that RANTES and CCR1 may play important roles in mast cell trafficking and related events in OLP.

Comparison of five selective media for the growth and enumeration of Streptococcus mutans

BACKGROUND

Although a few growth media are available for selective isolation of the cariogenic bacteria, Streptococcus mutans (S. mutans), it is still unclear as to which is the most efficacious. This study compared the selectivity and sensitivity of five different media for growing a laboratory strain of S. mutans (NCTC 10449), and for enumerating S. mutans from teeth of a group of young children, aged 2-10 years.

METHODS

The media tested in this study were mitis salivarius with bacitracin (MSB), mitis salivariuskanamycin-bacitracin (MSKB), glucose-sucrose-tellurite-bacitracin (GSTB), trypticase soy-sucrose-bacitracin (TYS20B) and tryptone-yeast-cysteine-sucrose-bacitracin (TYCSB) agars. These were prepared according to the respective manufacturer's instructions.

RESULTS

The results showed that at concentrations of bacteria 1 x 10(3) to 1 x 10(10)/mL, the recovery of the laboratory S. mutans strain was highest in TYCSB agar, followed by in descending order by TYS20B, MSB, GSTB, and MSKB (p<0.01). Similar results were obtained using dental plaque samples collected from swabs of the teeth of a group of children. In the clinical samples, TYCSB again showed the highest recovery rates of S. mutans compared to the other four media. Results were reproduced at dilutions of the samples at 1:20 x 10(6) to 1:2 x 10(6), and S. mutans concentrations of 1.6 to 7.7 Log 10 CFU/mL. In addition, there were highest ratios of mutans to non-mutans bacteria in TYCSB compared to the other media, suggesting high selectivity of this media for mutans species.

CONCLUSION

The results of our study suggest that TYCSB is the most sensitive and selective media for culture of S. mutans for laboratory and clinical studies.

Oral colonization of Streptococcus mutans in six-month-old predentate infants

We hypothesize that S. mutans colonization occurs more frequently in pre-term children due to their relative immaturity. In this study of 172 predentate, six-month-old infants, we found that 50% of pre-term and 60% of full-term children harbored S. mutans. The colonization was confirmed by repeat sampling. Although there were minor differences, factors associated with S. mutans infection in pre-term and full-term infants were generally similar. In both groups, increased frequency of sugar was ranked the most important factor (p < 0.001), followed by breast-feeding (p < 0.001), and habits which allowed saliva transfer from mother to infant (p < 0.01). By contrast, non-colonization of S. mutans was associated with multiple courses of antibiotics (p < 0.001). Compared with pre-term children, there were higher percentages of full-term who had night feedings and consumed sugar during sleep times. Mothers with infected infants had S. mutans levels > 5 x 10(5) CFU/mL saliva (p < 0.001), poorer oral hygiene, more periodontal disease, and lower socio-economic status (p < 0.02) and snacked frequently (p < 0.001), compared with mothers with non-infected infants.

Association of Streptococcus mutans infection and oral developmental nodules in pre-dentate infants

Since dental caries may present soon after tooth eruption, we hypothesized that colonization of Streptococcus mutans can occur in the predentate stages. In this study, we examined S. mutans colonization and its association with oral developmental nodules (Bohn's nodules) in 60 pre-term and 128 full-term, three-month-old infants. Overall, S. mutans was cultured from 30% (56/188) of the infants, and oral developmental nodules were noted in 55% (103/188). Compared with the pre-term, full-term infants showed a higher prevalence of S. mutans (34% vs. 20%, p < 0.02) as well as developmental nodules (61% vs. 42%, p < 0.05). In both groups, S. mutans was positively associated with numbers of developmental nodules in a dose-response relationship (p < 0.001), and with maternal salivary levels of the bacteria (p = 0.03). The permanence of S. mutans infection was confirmed by repeat saliva sampling at 6 months of age. Our results thus showed that many infants have already acquired S. mutans at 3 months of age, prior to tooth eruption.

A fluorometric microassay for histamine release from human gingival mast cells

Mast cells are important effector cells of the immune system. We describe a rapid and inexpensive microassay to determine histamine release from human gingival mast cells. The assay is based on the coupling of histamine with o-phthalaldehyde (OPT) at a highly alkaline pH to form a fluorescent product. Using this assay with a sample volume of 10 microl/well in a 384 black well microplate, the histamine detection limit was 0.031 microg/ml. The human mast cell line (HMC-1) and fresh mast cells isolated from human gingival tissue (n = 10) were stimulated with substance P, anti-IgE or calcium ionophore A23187. Calcium ionophore significantly increased histamine release from HMC-1 cells and gingival mast cells (p < 0.05). This microassay will facilitate the study of mast cell histamine release in diseased oral mucosa.