Journal of Dentistry

Editorial Board

2010-04-01

Endodontic therapy using magnification devices: A systematic review

Massimo Del Fabbro, Silvio Taschieri — 2010-02-01

Abstract: Objectives: The purpose of this systematic review was to investigate if the use of magnification devices in endodontics is associated with the improvement of clinical and radiographic outcomes.Data: The treatment success as determined by clinical and radiographic evaluation after 1-year follow-up was the main outcome. The main search terms used alone or in combination were: endodontic treatment, endodontic therapy, endodontic surgery, apicoectomy, periapical surgery, microscope, endoscope, loupes, magnification devices.Sources: The authors searched MEDLINE, Embase, Cochrane Oral Health Specialized Register, Cochrane Central Register of Controlled Trials for articles published up to September 2009 plus hand-searching of relevant journals and reference list of pertinent reviews and included studies.Study selection: Prospective clinical trials comparing endodontic therapy performed with or without using magnification devices, as well as trials comparing two or more magnification devices for endodontic therapy were considered.Conclusions: Three prospective studies were included, all dealing with endodontic surgery. No significant difference in outcomes was found among patients treated using magnifying loupes, surgical microscope or endoscope. Similarly, no difference was found with or without using the endoscope. No comparative study on magnification devices was found regarding orthograde endodontic treatment. The type of magnification device per se can only minimally affect the treatment outcome. Well-designed randomized trials should be performed to determine the true difference in treatment outcomes when using a magnification device in both orthograde and surgical endodontic treatment, if any exist.

Six-month evaluation of adhesives interface created by a hydrophobic adhesive to acid-etched ethanol-wet bonded dentine with simplified dehydration protocols

2009-12-07

Abstract: Objectives: To evaluate the efficacy of simplified dehydration protocols, in the absence of tubular occlusion, on bond strength and interfacial nanoleakage of a hydrophobic experimental adhesive blend to acid-etched, ethanol-dehydrated dentine immediately and after 6 months.Methods: Molars were randomly assigned to 6 treatment groups (n=5). Under pulpal pressure simulation, dentine crowns were acid-etched with 35% H3PO4 and rinsed with water. Adper Scotchbond Multi-Purpose was used for the control group. The remaining groups had their dentine surface dehydrated with ethanol solutions: group 1=50%, 70%, 80%, 95% and 3×100%, 30s for each application; group 2 the same ethanol sequence with 15s for each solution; groups 3, 4 and 5 used 100% ethanol only, applied in seven, three or one 30s step, respectively. After dehydration, a primer (50% BisGMA+TEGDMA, 50% ethanol) was used, followed by the neat comonomer adhesive application. Resin composite build-ups were then prepared using an incremental technique. Specimens were stored for 24h, sectioned into beams and stressed to failure after 24h or after 6 months of artificial ageing. Interfacial silver leakage evaluation was performed for both storage periods (n=5 per subgroup).Results: Group 1 showed higher bond strengths at 24h or after 6 months of ageing (45.6±5.9a/43.1±3.2aMPa) and lower silver impregnation. Bond strength results were statistically similar to control group (41.2±3.3ab/38.3±4.0abMPa), group 2 (40.0±3.1ab/38.6±3.2abMPa), and group 3 at 24h (35.5±4.3abMPa). Groups 4 (34.6±5.7bc/25.9±4.1cMPa) and 5 (24.7±4.9c/18.2±4.2cMPa) resulted in lower bond strengths, extensive interfacial nanoleakage and more prominent reductions (up to 25%) in bond strengths after 6 months of ageing.Conclusions: Simplified dehydration protocols using one or three 100% ethanol applications should be avoided for the ethanol-wet bonding technique in the absence of tubular occlusion, as they showed decreased bond strength, more severe nanoleakage and reduced bond stability over time.

Comparison of in vitro erosion potentials between beverages available in the United Kingdom and the United States

Sarah Murrell, Teresa A. Marshall, Paula J. Moynihan, Fang Qian, James S. Wefel — 2009-12-04

Abstract: Objective: Our objective was to compare the physiochemical properties and erosion potentials between beverages available in the UK and the US.Methods: The physiochemical properties (pH, titratable acidity and fluoride concentration) and erosion potential on enamel surfaces of beverages available in the UK were compared to similar beverages from the US. Enamel windows were exposed to beverages for 25h. Teeth were sectioned through the windows, and lesion depths were defined as the average distance between the original tooth structure and the base of demineralization.Results: The pH was lower in UK apple juice, orange juice, Diet Pepsi® and Sprite Zero® (p<0.05), and higher in UK orange soda and diet orange soda than in similar US beverages (p<0.05). Titratable acidities were higher in UK apple juice, orange juice, orange soda, diet orange soda and Sprite® (p<0.01), and lower in UK Sunny D® than in the US counterpart (p<0.001). Fluoride concentrations were lower in UK apple juice, orange juice, Coke®, and Diet Coke®, Sprite® and Sprite Zero® (p<0.001), and higher in UK orange soda, diet orange soda, Pepsi® and Diet Pepsi® than in their US counterparts (p<0.001). Lesion depths were higher in UK apple juice, orange juice, Diet Coke®, Sprite® and Sprite Zero® than in their US counterparts (p<0.05). Lesion depths were associated with pH (p=0.010) and country of origin (p=0.002).Conclusions: Under similar laboratory conditions, the physiochemical properties and erosion potentials on enamel surfaces differed between some, but not all, beverages available in the UK and the US.

A suitable base material for composite resin restorations: Zinc oxide eugenol

Li-Hong He, David G. Purton, Michael V. Swain — 2009-12-04

Abstract: Objective: This in vitro study evaluated the effects of a zinc oxide eugenol (ZOE) base on the mechanical properties of a composite resin restoration.Methods: Class I cavities were prepared on plastic teeth and filled with ZOE plus composite resin, following standard clinical procedures. The samples were sectioned sagittally and the ZOE–resin interface was exposed. After polishing, nanoindentation was performed on the region near the interface, and elastic modulus and hardness were plotted in the form of a color contour map. SEM was employed to observe the interface between composite resin and ZOE base.Results: In the region close to the ZOE base, the elastic modulus and hardness of composite resin reduced to the values of 9.71±0.54 and 0.51±0.05GPa, respectively. Eugenol from ZOE had detrimental effects on the composite resin only to a distance of less than 100μm from the ZOE base.Conclusion: Although eugenol suppresses polymerization slightly, by considering the biological advantages of ZOE, together with the results of the current investigation, ZOE may still be considered a suitable base material for composite resin. Bonding is essential for composite resin restorations over ZOE bases to avoid shrinkage detachment.

Systemic disorders and their influence on the development of dental hard tissues: A literature review

Michael Atar, Egbert J. Körperich — 2009-12-10

Abstract: Objectives: This report highlights the influence of a number of disorders with systemic physiological effects that impact on the development of dental hard tissues. It focuses in particular, on the pathological effects of systemic conditions with less well recognised, but no less important, impacts on dental development. Such conditions, include cystic fibrosis, HIV/AIDS, leukaemia, Alstrom syndrome, hypophosphatasia, Prader-Willi syndrome, Tricho-dento-osseous syndrome, tuberous sclerosis, familial steroid dehydrogenase deficiency and epidermolysis bullosa. These, along with developmental and environmental causes of enamel and dentine defects, are discussed and the possible aetiology of such effects are proposed. Furthermore, the dental management and long-term dental care of these patients is outlined.Sources: MEDLINE/PubMed.Conclusions: Enamel and dentine defects can present with a wide spectrum of clinical features and may be caused by a variety of factors occurring throughout tooth development from before birth to adulthood. These may include host traits, genetic factors, immunological responses to cariogenic bacteria, saliva composition, environmental and behavioural factors and systemic diseases. These diseases and their spectrum of clinical manifestations on the organs affected (including the dentition) require an increased knowledge by dental practitioners of the disease processes, aetiology, relevant treatment strategies and prognosis, and must encompass more than simply the management of the dental requirements of the patient. It is important that the impact of the disease and its treatment, particularly in respect of immunosuppression where dental interventions may become life-threatening, is also taken into consideration.

The efficacy and safety of articaine versus lignocaine in dental treatments: A meta-analysis

Vandana Katyal — 2009-12-14

Abstract: Objectives: Although articaine has been recommended for providing an improved local anaesthetic effect in patients presenting for dental treatments, a relevant meta-analysis has been lacking. Despite articaine's popularity, there is contradictory evidence to support the claims. The aim of this systematic review was to compare the efficacy and safety of articaine with lignocaine in maxillary and mandibular infiltrations and block anaesthesia in patients presenting for routine dental treatments.Data sources: The following databases were searched: Cochrane Central, Medline, Embase, and ProQuest Health and Medical Complete. In addition, the metaRegister of the controlled trials database was searched to identify dissertations and ongoing or unpublished trials, and the Australian division of Septodont (the manufacturer of articaine and lignocaine) was contacted. The bibliographies of identified articles were also searched.Study selection: Inclusion was limited to: (1) randomized controlled trials in patients requiring non-complex routine dental treatments; (2) interventions comparing 4% articaine (1:100,000 epinephrine) with 2% lignocaine (1:100,000 epinephrine) for maxillary and mandibular infiltrations and block anaesthesia; and (3) with principal outcome measures of anaesthetic success, post-injection adverse events or post-injection pain. Trial quality was evaluated by assessing randomization, allocation concealment, blinding, intention to treat analyses and how losses to follow up were addressed. Treatment effects were combined by meta-analysis using the random effects method.Results: Articaine is more likely than lignocaine to achieve an anaesthetic success in the posterior first molar area with a relative risk for success at 1.31 (95% CI 1.12–1.54, P=0.0009). There is no difference in post-injection adverse events between articaine and lignocaine with a relative risk of 1.05 (95% CI 0.66–1.65, P=0.85). However, articaine injection results in a higher pain score as measured by Visual Analogue Scale, than lignocaine at the injection site after anaesthetic reversal with a weighted mean difference of 6.49 (95% CI 0.02–12.96, P=0.05) decreasing to 1.10 (95% CI 0.18–2.02, P=0.02) on the third day after injection.Conclusion: The results of this systematic review provide support for the argument that articaine is more effective than lignocaine in providing anaesthetic success in the first molar region for routine dental procedures. In addition, both drugs appear to have similar adverse effect profiles. The clinical impact of articaine's higher post-injection pain scores than lignocaine is negligible. Hence, articaine is a superior anaesthetic to lignocaine for use in routine dental procedures. Use in children under 4 years of age is not recommended, since no data exists to support such usage.

Fatigue and damage accumulation of veneer porcelain pressed on Y-TZP

2009-12-21

Abstract: Objectives: This study compared the reliability and fracture patterns of zirconia cores veneered with pressable porcelain submitted to either axial or off-axis sliding contact fatigue.Methods: Forty-two Y-TZP plates (12mm×12mm×0.5mm) veneered with pressable porcelain (12mm×12mm×1.2mm) and adhesively luted to water aged composite resin blocks (12mm×12mm×4mm) were stored in water at least 7 days prior to testing. Profiles for step-stress fatigue (ratio 3:2:1) were determined from single load to fracture tests (n=3). Fatigue loading was delivered on specimen either on axial (n=18) or off-axis 30° angulation (n=18) to simulate posterior tooth cusp inclination creating a 0.7mm slide. Single load and fatigue tests utilized a 6.25mm diameter WC indenter. Specimens were inspected by means of polarized-light microscope and SEM. Use level probability Weibull curves were plotted with 2-sided 90% confidence bounds (CB) and reliability for missions of 50,000 cycles at 200N (90% CB) were calculated.Results: The calculated Weibull Beta was 3.34 and 2.47 for axial and off-axis groups, respectively, indicating that fatigue accelerated failure in both loading modes. The reliability data for a mission of 50,000 cycles at 200N load with 90% CB indicates no difference between loading groups. Deep penetrating cone cracks reaching the core–veneer interface were observed in both groups. Partial cones due to the sliding component were observed along with the cone cracking for the off-axis group. No Y-TZP core fractures were observed.Conclusions: Reliability was not significantly different between axial and off-axis mouth-motion fatigued pressed over Y-TZP cores, but incorporation of sliding resulted in more aggressive damage on the veneer.

Setting of commercial glass ionomer cement Fuji IX by 27Al and 19F MAS-NMR

Tais Munhoz, Natalia Karpukhina, Robert G. Hill, Robert V. Law, L.H. De Almeida — 2009-12-30

Abstract: Objectives: To investigate the long term setting reaction in the glass ionomer restorative, Fuji IX, by monitoring the structural evolution of aluminium and fluorine species using 27Al and 19F MAS-NMR spectroscopy.Methods: Fuji IX cements aged from 5min up to 3 months were prepared according to the manufacturer instructions from the commercial material. The 27Al and 19F MAS-NMR studies were carried out on powders made after terminating the setting reaction.Results: 27Al MAS-NMR results show conversion of aluminium from the glass phase, where it has coordination number four, Al(IV), into the cement matrix where it has a coordination number of six, Al(VI). At least two different Al(VI) species were detected at short ageing time cements. Assignment of these species is discussed and compared with the data from other sources. The possibility for a condensed aluminium species [Al13(OH)24(H2O)12]7+ to form is considered. The ratio of aluminium in the cement, Al(VI), to the remaining unreacted in glass has been evaluated by deconvolution of the spectra. Various theoretical ratios of aluminium species in the cement matrix to the unreacted ones remaining in glass have been estimated. The 19F MAS-NMR spectra are identical for the glass and cements at the early times and contain a dominant signal assigned to Al–F–Sr(n).Conclusions: The data confirms that the conversion of aluminium is a diffusion-controlled process at early stage less than 1h and it is largely complete between 1 and 6h. The comparison with the experimental data shows that the majority of aluminium cations do not form tricarboxylates but are coordinated with one or two carboxylic groups and other ligands. Insufficient amount of water and excess of glass in this cement formulation affect glass degradation mechanism.

HEMA reactivity with demineralized dentin

Patrick Sharrock, Geneviève Grégoire — 2009-12-25

Abstract: Objectives: 2-Hydroxyethylmethacrylate (HEMA) was compared to its epoxy analogue, glycidoxypropylmethacrylate (GMA), for reactivity with 2,6-diaminohexanoic acid (Lysine), an amino acid present in collagen possessing a reactive amino side chain. The aim was to verify whether HEMA could chemically react with collagen fibers.Methods: Capillary electrophoresis was used to analyse reaction products together with computer aided chemistry. Retention of HEMA in demineralized dentine particles was investigated by infrared spectroscopy.Results: It was found by that HEMA does not form any new molecular species when contacted with lysine whereas GMA completely reacts to form the expected addition product. Computer aided chemistry confirmed this finding. Infrared spectroscopy showed that demineralized dentin has strong affinity for HEMA and retains this monomer despite extensive water washing.Conclusions: We interpret this behavior as demonstrating solvation of HEMA in the collagen polymer network.

Influence of the degree of dentine mineralization on pulp chamber temperature increase during resin-based composite (RBC) light-activation

2009-12-31

Abstract: Objectives: To analyse the influence of the degree of dentine mineralization on the pulp chamber temperature increase during composite light-activation.Methods: Dentine discs (2mm thick) obtained from recently extracted teeth or those with extensive dentine sclerosis were analysed by FT-IR spectrometry in order to choose the two discs with the greatest difference in the degree of mineralization. A model tooth was set up with the dentine discs between a molar with the pulp chamber exposed and a crown with a standardized class II cavity. A K-type thermocouple was introduced into the molar root until it came into contact with the dentine discs and the cavity was filled with P60 resin composite. The temperature rise was measured for 120s after light-activation began: Standard (S) 600mW/cm2/40s; Ramp (R) 0→800mW/cm2/10s+800mW/cm2/10s; Boost (B) 850mW/cm2/10s and LED (L) 1.300mW/cm2/40s (n=10). The same protocol was repeated after grinding the dentine discs to 1.0 and 0.5mm thickness.Results: The temperature increase was significantly higher in dentine with high degree of mineralization (p<0.05). With respect to the dentine thickness, the following result was found: 2mm<1mm<0.5mm (p<0.05). The light-activation mode also presented significant difference as follows: S>R=L>B (p<0.05).Conclusions: The higher the degree of dentine mineralization the greater the increase in pulp chamber temperature. The temperature increase was influenced by the light-polymerization mode and dentine thickness.

Real-time measurement of dentinal fluid flow during amalgam and composite restoration

Sun-Young Kim, Jack Ferracane, Hae-Young Kim, In-Bog Lee — 2010-01-11

Summary: Objectives: This study examined changes in the dentinal fluid flow (DFF) during restorative procedures and compared permeability after restoration among restorative materials and adhesives.Methods: A class 1 cavity was prepared and restored with either amalgam (Bestaloy), or composite (Z-250) with one of two etch-and-rinse adhesives (Scotchbond MultiPurpose: MP and Single Bond 2: SB) or one of two self-etch adhesives (Clearfil SE Bond: CE and Easy Bond: EB) on an extracted human third molar which was connected to a sub-nanoliter fluid flow measuring device (NFMD) under 20cm water pressure. DFF was measured from the intact tooth state through the restoration procedures to 30min after restoration, and re-measured at 3 and 7 days post-restoration.Results: Inward flow during cavity preparation was followed by outward flow after preparation. In amalgam restoration, the outward flow changed into an inward flow during amalgam filling, which was followed by a slight outward flow after finishing. In composite restoration, MP and SB showed an inward flow and outward flow for the rinsing and drying steps, respectively. Application of a hydrophobic bonding resin in the MP and CE systems caused a decrease in the flow rate. Air-drying of solvent for the CE and EB systems caused a sudden outward flow, whereas light-curing of the adhesive and composite caused an abrupt inward flow.Conclusions: Each restorative step clearly changed the direction and the rate of the DFF during restoration, which could be well identified with NFMD.

Comparing two quantitative methods for studying remineralization of artificial caries

E.C.M. Lo, Q.H. Zhi, A. Itthagarun — 2010-01-14

Abstract: Objectives: To compare the detection of changes before and after remineralization of artificial enamel and dentin caries by microCT scanning, polarized light microscopy (PLM) and transverse microradiography (TMR).Methods: Fourteen extracted premolars were cut into tooth blocks and painted with an acid-resistant varnish leaving one enamel and one dentin surface exposed. The tooth blocks were immersed into demineralizing solution for 4 days to produce artificial caries-like lesions and scanned by microCT. Then the 14 tooth blocks were randomly allocated into two groups. Seven tooth blocks in Group I were cut longitudinally through the exposed surface into 100–150μm thick sections and microradiographs were taken. The other seven tooth blocks in Group II were left intact. All the tooth blocks and sections were then immersed into remineralizing solution for 5 days. PLM and TMR of the tooth sections in Group I were taken again. Depth of the lesion on the TMR was measured. Tooth blocks in Group II were scanned by microCT.Results: Mean lesion depth in Group I reduced by 13.0% and 8.2% after remineralization for enamel and dentin, respectively (paired t-test, P<0.001). In Group II, linear attenuation coefficient (LAC) of the region of interest (ROI) increased by 11.1% and 23.8% after remineralization for enamel and dentin lesions, respectively (paired t-test, P<0.001).Conclusion: Both microCT and microradiography are able to detect a change of similar magnitude in the artificial caries lesions after remineralization. MicroCT may be used to substitute TMR and PLM in in vitro studies about caries.