Pilot clinical study to evaluate the efficacy of a professionally delivered high fluoride varnish on erosive tooth wear in an in-situ model

OBJECTIVES

The aim for this pilot study was to investigate the effect of a sodium fluoride varnish on step height measured by a profilometer from human enamel worn by healthy volunteers with a novel in situ/ex vivo erosion design.

METHOD

Healthy volunteers aged 18-70 years wore a palatal splint containing 8 human enamel samples and underwent two 3-day treatment periods for 6 h a day with a varnish containing sodium fluoride at 22,600 ppm and the control with the same ingredients but without fluoride. Each splint contained 4 polished and 4 unpolished samples. The interventions were applied to the surface of the enamel samples in randomised order, removed after 6 h, then immersed ex-vivo in 1 %, pH 2.7 citric acid for 2 min, repeated 4 times a day, over 2 days. Measurements of enamel were assessed blindly by microhardness on day 2 and by non-contact laser profilometry on day 3 for the two treatments.

RESULTS

24 volunteers, 2 males and 22 females aged 27-54 years, were screened and recruited. The delta microhardness, from polished samples removed at the end of day 2, for the control and fluoride treatment was 95.7 (22.9) kgf/mm2 and 123.7 (28.9) kgf/mm2, respectively (p < .005). The mean (SD) step height for the control polished enamel surfaces was 3.67 (2.07) µm and for the fluoride varnish was 1.79 (1.01) µm (p < .0005). The control unpolished enamel surfaces had a mean 2.09 (1.53) µm and the fluoride varnish was 2.11 (1.53) µm but no statistical difference was detected.

CONCLUSIONS

The results from this pilot study, utilizing an in-situ model where enamel was exposed to acid over the course of 2 days, demonstrated that a high fluoride varnish containing sodium fluoride at 22,600 ppm prevented erosive wear compared to a control on the polished enamel surfaces.

CLINICAL SIGNIFICANCE

Intra-oral study demonstrated that a high fluoride varnish containing sodium fluoride at 22,600 ppm reduced erosive tooth wear.

Frequency of Locator Legacy Insert Changes With Implant Overdentures in a UK Population

PURPOSE

To determine the frequency of insert changes for combined maxillary and mandibular implant overdentures (IOD) using the Locator Legacy system. A secondary objective was to assess the survival of dental implants with IODs.

MATERIALS AND METHODS

This retrospective audit reviewed clinical records with up to 12 years follow up from 785 patients who received IODs using the Locator system at a dental hospital. From these, 151 had a combined maxillary opposed by a mandibular IOD and from this, 37 had data retrieved using a minimum data set. The frequency of insert change was recorded and descriptive analysis was provided by means and standard deviations for continuous variables. Frequencies of categorical values were reported as percentages.

RESULTS

222 implants were placed on 21 men, 16 women with a mean age 67.5 years (SD 8.8). All patients were reviewed at least once. Maxillary and mandibular IODs experienced 1.9 (SD 2.0) and 1.2 (SD 1.2) mean insert changes per patient, respectively. The mean time (SD) between initial and first insert change for maxillary and mandibular IODs was 3.4 months (SD 3.2) and 6.4 months (SD 7.2) and between the first and second insert change was 9.9 months (SD 9.0) and 10.0 months (SD 8.3), respectively. Implant failure was 21.6% and 2.7% in the maxilla and mandible respectively.

CONCLUSIONS

Clinicians should anticipate the first insert change around 3 months for maxillary IOD and 6 months for mandibular IOD. Subsequently, the second insert change to be around 10 months for both maxillary and mandibular IODs.

Use of polyvinyl siloxane impressions to monitor sub-5-μm erosive tooth wear on unpolished enamel

STATEMENT OF PROBLEM

Whether polyvinyl siloxane impressions are capable of reproducing 5-μm changes on natural freeform enamel and potentially enabling clinical measurements of early surface changes consistent with wear of teeth or materials is unclear.

PURPOSE

The purpose of this in vitro study was to investigate and compare polyvinyl siloxane replicas with direct measurements of sub-5-μm lesions on unpolished human enamel lesions by using profilometry, superimposition, and a surface subtraction software program.

MATERIAL AND METHODS

Twenty ethically approved unpolished human enamel specimens were randomized to a previously reported cyclic erosion (n=10) and erosion and abrasion (n=10) model to create discrete sub-5-μm lesions on the surface. Low viscosity polyvinyl siloxane impressions were made of each specimen before and after each cycle and scanned by using noncontacting laser profilometry and viewed with a digital microscopy and compared with direct scanning of the enamel surface. The digital maps were then interrogated with surface- registration and subtraction workflows to extrapolate enamel loss from the unpolished surfaces by using step-height and digital surface microscopy to measure roughness.

RESULTS

Direct measurement revealed chemical loss of enamel at 3.4 ±0.43 μm, and the polyvinyl siloxane replicas were 3.20 ±0.42 μm, respectively. For chemical and mechanical loss direct measurement was 6.12 ±1.05 μm and 5.79 ±1.06 μm for the polyvinyl siloxane replica (P=.211). The overall accuracy between direct and polyvinyl siloxane replica measurements was 0.13 +0.57 and -0.31 μm for erosion and 0.12 +0.99 and -0.75 μm for erosion and abrasion. Surface roughness and visualization with digital microscopy provided confirmatory data.

CONCLUSIONS

Polyvinyl siloxane replica impressions from unpolished human enamel were accurate and precise at the sub-5-μm level.

Pediatric patients' reasons for visiting dentists in all WHO regions

BACKGROUND

Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact are the four oral health-related quality of life (OHRQoL) dimensions (4D) or areas in which oral disorders impact pediatric patients. Using their dentists' assessment, the study aimed to evaluate whether pediatric dental patients' oral health concerns fit into the 4D of the Oral Health-Related Quality of Life (OHRQoL) construct.

METHODS

Dentists who treat children from 32 countries and all WHO regions were selected from a web-based survey of 1580 international dentists. Dentists were asked if their pediatric patients with current or future oral health concerns fit into the 4D of the Oral Health-Related Quality of Life (OHRQoL) construct. Proportions of all pediatric patients' oral health problems and prevention needs were computed.

FINDINGS

Data from 101 dentists treating children only and 523 dentists treating children and adults were included. For 90% of pediatric patients, their current oral health problems fit well in the four OHRQoL dimensions. For 91% of oral health problems they intended to prevent in the future were related to these dimensions as well. Both numbers increased to at least 96% when experts analyzed dentists´ explanations of why some oral health problems would not fit these four categories.

CONCLUSIONS

The study revealed the four fundamental components of dental patients, i.e., the four OHRQoL dimensions (Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact) are also applicable for pediatric patients, regardless of whether they have current or future oral health concerns, and should be considered when measuring OHRQoL in the pediatric dental patient population.

Why Patients Visit Dentists - A Study in all World Health Organization Regions

OBJECTIVE

The dimensions of oral health-related quality of life (OHRQoL) Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact are the major areas where patients are impacted by oral diseases and dental interventions. The aim of this study was to evaluate whether dental patients' reasons to visit the dentist fit the 4 OHRQoL dimensions.

METHODS

Dentists (N = 1580) from 32 countries participated in a web-based survey. For their patients with current oral health problems, dentists were asked whether these problems were related to teeth, mouth, and jaws' function, pain, appearance, or psychosocial impact or whether they do not fit the aforementioned 4 categories. Dentists were also asked about their patients who intended to prevent future oral health problems. For both patient groups, the proportions of oral health problems falling into the 4 OHRQoL dimensions were calculated.

RESULTS

For every 100 dental patients with current oral health problems, 96 had problems related to teeth, mouth, and jaws' function, pain, appearance, or psychosocial impact. For every 100 dental patients who wanted to prevent future oral health problems, 92 wanted to prevent problems related to these 4 OHRQoL dimensions. Both numbers increased to at least 98 of 100 patients when experts analyzed dentists' explanations of why some oral health problems would not fit the four dimension. For the remaining 2 of 100 patients, none of the dentist-provided explanations suggested evidence against the OHRQoL dimensions as the concepts that capture dental patients' suffering.

CONCLUSION

Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact capture dental patients' oral health problems worldwide. These 4 OHRQoL dimensions offer a psychometrically sound and practical framework for patient care and research, identifying what is important to dental patients.

Measurement of surface roughness changes of unpolished and polished enamel following erosion

Objectives

To determine if Sa roughness data from measuring one central location of unpolished and polished enamel were representative of the overall surfaces before and after erosion.

Methods

Twenty human enamel sections (4x4 mm) were embedded in bis-acryl composite and randomised to either a native or polishing enamel preparation protocol. Enamel samples were subjected to an acid challenge (15 minutes 100 mL orange juice, pH 3.2, titratable acidity 41.3mmol OH/L, 62.5 rpm agitation, repeated for three cycles). Median (IQR) surface roughness [Sa] was measured at baseline and after erosion from both a centralised cluster and four peripheral clusters. Within each cluster, five smaller areas (0.04 mm²) provided the Sa roughness data.

Results

For both unpolished and polished enamel samples there were no significant differences between measuring one central cluster or four peripheral clusters, before and after erosion. For unpolished enamel the single central cluster had a median (IQR) Sa roughness of 1.45 (2.58) μm and the four peripheral clusters had a median (IQR) of 1.32 (4.86) μm before erosion; after erosion there were statistically significant reductions to 0.38 (0.35) μm and 0.34 (0.49) μm respectively (p<0.0001). Polished enamel had a median (IQR) Sa roughness 0.04 (0.17) μm for the single central cluster and 0.05 (0.15) μm for the four peripheral clusters which statistically significantly increased after erosion to 0.27 (0.08) μm for both (p<0.0001).

Conclusion

Measuring one central cluster of unpolished and polished enamel was representative of the overall enamel surface roughness, before and after erosion.

Effect of Model Variables on in vitro Erosion

The aim of this study was to investigate the effects of tooth type (molar/premolar), tooth surface (buccal/lingual), smear layer or no smear layer, storage of specimens in deionised water, mode and speed of agitation, and rinsing method between cycles on mean step height loss and Knoop microhardness (KHN) change. Polished human enamel specimens embedded in acrylic resin were prepared from sound permanent molar and premolar tooth surfaces. A 0.3% (pH 3.2) solution of citric acid was used to erode the specimens, in a cycling procedure, consisting of 10 min immersion followed by rinsing in deionised water for 30 s with a spray bottle, for 5 cycles. The specimens were analysed with a non-contact white light profilometer and KHN. Molar teeth (148.99±24.49 KHN) and buccal surfaces (155.62±30.35 KHN) produced significantly less microhardness change compared to premolar (186.40±20.74 KHN) and lingual surfaces (179.76±23.21 KHN; p<0001). The effect of storage and rinsing showed little difference in mean step height loss (<1 µm) and microhardness change. With no smear layer a significantly lower mean step height loss and microhardness change (p<0.001) was observed. Agitation was performed with Orbital, Gyro and See-Saw rockers at 30, 40, 60, and 70 rpm. The mean step height loss was largest for See-Saw at 70 rpm (11.73±0.91 μm) and lowest for Orbital at 30 rpm (2.76±1.12 μm). A statistical difference was found between all types of agitation and speeds (p<0.001). In conclusion, this study has shown that the variables investigated here have a significant impact on the measurable outcome, highlighting the importance of accurate and detailed method sections.

Intrusion of supraerupted maxillary molar using a high interim restoration on the defective opposing tooth: a clinical report

Wear, extraction, or fracture of all or part of a mandibular first molar can lead to the supraeruption of the opposing maxillary molar, resulting in occlusal interference and lack of restoration space. This report describes a method to gain sufficient vertical space for permanent restoration. A direct composite resin restoration was placed on the occlusal surface of a lower molar, intentionally making the interim restoration high and intruding the maxillary molar. After 6 weeks, the extruded tooth returned to the desired position, and functional occlusion was restored, enabling a ceramic restoration on the mandibular molar. No marked adverse sensory reaction was reported in this therapeutic process, and no deleterious signs were detected in the teeth, periodontium, or temporomandibular joints. The simple treatment type was effective, noninvasive, and time saving, while also preserving maximum tooth structures.

Comparison of the possible protective effect of the salivary pellicle of individuals with and without erosion

The acquired pellicle adheres to tooth surfaces and has been suggested to provide differing degrees of protection against acidic erosion. This study investigated whether pellicle formed on enamel blocks in patients suffering dietary dental erosion modified the effect of an in vitro simulated dietary challenge, in comparison with pellicle formed on enamel blocks in healthy subjects and to no-pellicle enamel samples. Sixty subjects recruited from dental erosion clinics were compared to healthy age-matched controls. Subjects wore a custom-made maxillary splint holding human enamel blocks for 1 h during which the acquired enamel pellicle was formed. Enamel blocks were removed from the splints and a simulated dietary erosive challenge of 10 min was performed. In addition the challenge was performed on 30 enamel samples without pellicle. Profilometry showed no statistical difference between samples from the erosion subjects with a mean step height of 1.74 µm (SD 0.88) and median roughness (Sa) of 0.39 µm (interquartile range, IQR 0.3-0.56) and the controls with 1.34 µm (SD 0.66) and 0.33 µm (IQR 0.27-0.38), respectively. The control samples without pellicle had Sa of 0.44 µm (IQR 0.36-0.69) and these differences were statistically significant compared to those from the healthy subjects (p = 0.002). Mean (SD) microhardness reduction with a 100-gram load for the erosion group was 113.5 (10) KHN, for healthy subjects was 93 (15.4) KHN and for the enamel samples without pellicle 139.6 (21.8) KHN and all groups were statistically different. The microhardness and roughness data suggested the pellicle influenced erosion under these study conditions.

Measuring enamel erosion: a comparative study of contact profilometry, non-contact profilometry and confocal laser scanning microscopy

OBJECTIVES

To compare three instruments for their ability to quantify enamel loss after acid erosion.

METHODS

6 randomized parallel groups of bovine enamel samples were subjected to citric acid (higher acidity) or orange juice (lower acidity) erosion and remineralisation in a cycling model. Two protected shoulders were created on each of the samples using tape, to serve as reference for analysis. The time of exposure to each acid was varied, along with presence or absence of agitation. After treatment, samples were measured on 3 instruments capable of measuring step height: a contact profilometer (CP); a non-contact profilometer (NCP); and a confocal laser scanning microscope (CLSM) by three different examiners. Additionally, 3D (volume) step height was also measured using the CLSM.

RESULTS

Increasing acid concentration and exposure time resulted in greater erosion, as did agitation of samples while in acid solution. All instruments/methods identified the same statistically significant (p<0.05) pair-wise differences between the treatments groups. Further, all four methods exhibited strong agreement (Intra-class correlation ≥ 0.96) in erosion level and were highly correlated, with correlations of 0.99 or higher in all cases.

SIGNIFICANCE

All instruments/methods used in this study produced very similar conclusions with regard to ranking of enamel loss, with data showing very high agreement between instruments. All instruments were found to be equally suited to the measurement of enamel erosion.

An experiment on the attrition of acid demineralized dentine in vitro

BACKGROUND

A laboratory investigation was designed to test the hypothesis that acids increase the rate of wear caused by attrition on dentine.

METHODS

Dentine sections from 10 teeth were polished, cleaned in an ultrasonic bath and divided into 8 equally sized areas. The occlusal tip of a tooth, placed vertically in a wear machine and loaded at 150 N, was moved against each dentine section for 5000 return strokes with artificial saliva acting as a lubricant. Each dentine section was divided into 8 sections and half randomly immersed in a 1% citric acid solution (pH 2.3) for 20 minutes. The wear regime produced 8 wear scars in total per dentine sample. The volume of each wear scar was measured using a contacting digitizing profilometer.

RESULTS

A total of 80 wear scars were produced with 40 treated with acid and 40 acting as controls. The mean for wear volume of the dentine scars with acid was 4.84 μm(3) (1.38) and for the non-acid surface 2.95 μm(3) (0.86). This difference was statistically significant (p < 0.05).

CONCLUSIONS

These results support the hypothesis that acids increase the rate of wear caused by attrition on dentine.

The effect of increasing sodium fluoride concentrations on erosion and attrition of enamel and dentine in vitro

OBJECTIVES

To investigate the effect of an aqueous sodium fluoride solution of increasing concentration on erosion and attrition of enamel and dentine in vitro.

METHODS

Enamel and dentine sections from caries-free human third molars were polished flat and taped (exposing a 3 mm x 3 mm area) before being randomly allocated to 1 of 5 groups per substrate (n=10/gp): G1 (distilled water control); G2 (225 ppm NaF); G3 (1450 ppm NaF); G4 (5000 ppm NaF); G5 (19,000 ppm NaF). All specimens were subjected to 5, 10 and 15 cycles of experimental wear [1 cycle=artificial saliva (2h, pH 7.0)+erosion (0.3% citric acid, pH 3.2, 5 min)+fluoride/control (5 min)+attrition (60 linear strokes in artificial saliva from enamel antagonists loaded to 300 g)]. Following tape removal, step height (SH) in mum was measured using optical profilometry.

RESULTS

When the number of cycles increased the amount of tooth surface loss increased significantly in enamel and dentine after attrition and erosion and for dentine after attrition. Attrition and erosion resulted in greater surface loss than attrition alone after 15 cycles of experimental wear of enamel. 5000 ppm and 19,000 ppm sodium fluoride solutions had a protective effect on erosive and attritional enamel tooth wear in vitro, however no other groups showed significant differences.

CONCLUSIONS

The more intensive the fluoride regime the more protection was afforded to enamel from attrition and erosion. However, in this study no such protective effect was demonstrated for dentine.

Prevalence of tooth wear in adults

PURPOSE

The aim of this study was to investigate data on the prevalence of tooth wear in adults and assess possible correlations using a systematic review.

MATERIALS AND METHODS

A search of the literature, using PubMed and the Cochrane Library, from January 1980 to July 2007 was made using keywords "tooth + wear"; "dental + attrition + prevalence"; "dental + wear + prevalence"; "erosion + prevalence"; and "abrasion + prevalence". References were independently screened for inclusion and exclusion by two investigators and Cohen Kappa was used as the measure of agreement. Data were collected and converted into the Smith and Knight Tooth Wear Index.

RESULTS

One hundred eighty-six references were initially selected and subjected to the systematic review procedure; 13 survived the inclusion procedure. Four articles were suitable for regression analysis at tooth level (R2 = .593) and 3 at subject level (R2 = .736), using "age and age squared" and "age squared" as variables, respectively. Six studies reported males having significantly more tooth wear than females.

CONCLUSION

The predicted percentage of adults presenting with severe tooth wear increases from 3% at the age of 20 years to 17% at the age of 70 years. Increasing levels of tooth wear are significantly associated with age.

Effect of resin coating on dentine compared to repeated topical applications of fluoride mouthwash after an abrasion and erosion wear regime

OBJECTIVES

The role of fluoride in preventing erosion and abrasion on dentine remains unclear. The aim of this study was to investigate the effect of repeated applications of a 0.05% fluoride mouthwash and an adhesive on wear of dentine using stainless steel discs reference points and a laser profilometer.

METHODS

Small stainless steel discs were bonded to 60 caries free extracted molars which had previously been sectioned horizontally. The teeth were equally divided and subjected to four modalities in an erosion and abrasion laboratory model. Step heights were measured from the metal discs using a non-contacting laser profilometer at 100, 500, 1000, 2500 and 5000 cycles.

RESULTS

The results after 5000 cycles showed that dentine coated with a dentine adhesive (0.015 microm, S.D. 0.090) had statistically less wear than fluoride (0.127 microm, S.D. 0.150), abrasion and erosion (0.182 microm, S.D. 0.150) or abrasion only (0.096 microm, S.D. 0.090) (p<0.001).

CONCLUSION

In conclusion dentine surfaces coated with a resin-based adhesive provided more protection against erosion and abrasion than a fluoride mouthrinse. There were no statistical differences between the modalities for cycles less than 5000.

The microhardness of bleached dentine and its bond strength to a dentine bonding agent

The aim of this study was to measure the hardness of a bleached dentine surface and its bond strength to a dentine-bonding agent. Thirty teeth were randomly divided into a test and control group. The teeth were hemi-sectioned, the cut surfaces ground flat and the test surfaces bleached with a 10% aqueous solution of carbamide peroxide continuously for 4 days. Hardness was determined using a Vickers microhardness test. The bond between Coltene 'One Coat Bond' and bleached and unbleached dentine was evaluated by measuring shear bond strength using an Instron machine. The mean hardness of dentine before and after bleaching was 62.5 (10.2) and 53.6 (7.3) and this difference was statistically different (p<0.001). For the controls immersed in water the hardness was before 60.8 (standard deviation: 7.2) and after 59.6 (8.2) respectively. The mean shear bond strength for the unbleached was 5.5MPa (1.6) and for the bleached samples was 3.3MPa (1.8) and this difference was statistically significant (p<0.002). Under these study conditions the Vickers hardness and bond strength to dentine was reduced by bleaching.

The Influence of Fluoride Varnish on the Attrition of Dentine

Previous investigations have shown the potential for fluoride to be protective in an abrasion/erosion laboratory model. The aim of this study was to investigate the effect of high concentrations of fluoride delivered in a varnish on attrition of dentine. Fifteen caries-free, intact lower third molar teeth were sectioned and the enamel removed by a water-cooled diamond disc. Polished dentine surfaces were divided into 8 areas, 4 of which were randomly covered with a high-concentration fluoride varnish for 24 h. The samples were subjected to 5,000 cycles of attrition bathed under artificial saliva. Microhardness testing adjacent to the wear scars showed no statistical difference between the fluoride-treated (71.42 KHN, SD 10.52) and control surfaces (72.66 KHN, SD 9.69). The volume of the wear scar was statistically greater for the fluoride-treated surface at 9.6 microm(3) (SD 4.92) and 8.13 microm(3) (SD 5.54) for the control areas (p = 0.029). The low pH of the fluoride varnish appears to have increased the amount of wear from attrition in this laboratory study.

A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion

The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear.

Downloadable computer models for renal replacement therapy

Mathematical models can predict solute clearances and solute concentrations during renal replacement therapy. At present, however, most nephrologists cannot use these models because they require mathematical software. In this report, we describe models of solute transport by convection and diffusion adapted to run on the commonly available software program Excel for Macintosh computers and PCs running Windows. Two programs have been created that can be downloaded from http://www.stanford.edu/~twmeyer/ or http://dev.satellitehealth.com/research/journal.asp. The first, called 'Dr Addis Clearance Calculator', calculates clearance values from inputs including the blood flow Q(b), the hematocrit, the ultrafiltration rate Q(f), the dialysate flow rate Q(d), the reflection coefficient sigma and the mass transfer area coefficient K(o)A for the solute of interest, and the free fraction f if the solute is protein bound. Solute concentration profiles along the length of the artificial kidney are displayed graphically. The second program, called 'Dr Coplon Dialysis Simulator', calculates plasma solute concentrations from the clearance values obtained by the first program and from additional input values including the number of treatments per week, the duration of the treatments, and the solute's production rate and volumes of distribution. The program calculates the time-averaged solute concentration and provides a graphic display of the solute concentration profile through a week-long interval.

An audit of study casts used to monitor tooth wear in general practice

OBJECTIVE

To assess the outcome of compliance of advice sent to patients and dentists about monitoring tooth wear in general practice.

METHOD

Postal questionnaires were sent to 70 patients and their dentists requesting information on the outcome of letters of advice sent to general dental practitioners regarding monitoring tooth wear with study casts. They also requested information about the reasons for the patients' referral, the outcome of treatment and whether study models had been taken.

RESULTS

Replies were received from 60 dentists (87%) and 53 patients (75%). Of these, 16 patients and 16 dentists had moved from their recorded address. Study casts were reported as having been taken by 23 dentists (38%) and reported by 18 patients (34%). The most common reason for referral was advice about monitoring the wear and the appearance of their teeth.

CONCLUSIONS

The compliance of the patients and dentists in monitoring tooth wear by using study casts in general practice was not successful. It raises issues regarding the value of consultant advice letters to this common clinical problem.

The association of acidic reflux above the upper oesophageal sphincter with palatal tooth wear

This case-controlled clinical study, conducted at a secondary care unit, compared pH measurement at 2 cm above the upper oesophageal sphincter (UOS) in 31 patients complaining of extra-oesophageal symptoms of reflux to 7 control subjects. Twenty-four-hour ambulatory pH measurements were recorded and analysed at 5 cm above the lower oesophageal sphincter (LOS) and 2 cm above the UOS. In reflux patients the proportion of supine time when pH at 5 cm above the LOS was <4 was significantly greater than in controls. The proportion of time when pH at 2 cm above the UOS was <5.5 was also significantly greater in patients than in controls. Palatal tooth wear observed in the patient group correlated with acid reflux at night. In this group of patients presenting with symptoms of reflux, gastric acid passed through the upper oesophageal sphincter and increased the potential for erosion.

The role of erosion in tooth wear: aetiology, prevention and management

Tooth wear is a universal experience. The cause is usually a combination of erosion, attrition and abrasion. Attrition usually presents with flattened incisal and occlusal tooth surfaces which accurately inter-digitate. Erosion from dietary or gastric acids forms smooth lesions which typically appear as cupped occlusal/incisal and concave buccal/facial surfaces. When combined with attrition or abrasion, acids have the potential to cause significant wear. Wear reduces the thickness of enamel exposing the underlying dentine and changing the colour from the white of enamel to yellow of dentine. Acids causing erosion originate from the stomach or from the diet. Gastric acid is associated with reflux disease and eating disorders. The frequency of acidic foods and drinks and how they are consumed is important in dietary erosion. The progression of tooth wear is recognised to be slow with periods of activity and inactivity. Although restorations can be indicated, prevention and monitoring remain important strategies in maintaining the life of the teeth.

Three patient reports illustrating the use of dentin adhesives to cement crowns to severely worn teeth

PURPOSE

Severely worn and broken down teeth present clinical treatment planning dilemmas. Extreme examples of worn teeth present in patients suffering from bulimia nervosa and dentinogenesis imperfecta. Bulimia nervosa typically presents early in adult life with a myriad of clinical features and a most important dental sign of eroded palatal surfaces on the maxillary teeth. Dentinogenesis imperfecta is a relatively uncommon disorder that presents with varying severity of unsupported enamel and results in teeth more susceptible to wear.

MATERIALS AND METHODS

Dental treatment for both conditions when wear has resulted in the complete loss of the tooth can either be directed toward restoring remaining tooth tissue or extraction and replacement with implants or dentures. This article presents the clinical management of three case histories, each with one or more severely broken down teeth, which were restored with adhesively retained crowns.

RESULTS

Treatment lasted nearly 10 years in one patient and failed after 6 years in another. The third patient was treated more recently.

CONCLUSION

All three case histories serve as examples of using adhesive cements to retain indirect restorations as a possible prosthodontic management strategy.

The surface effects of erosion and abrasion on dentine with and without a protective layer

OBJECTIVE

The aim of this in situ study was to investigate with four imaging modalities whether covering dentine with adhesive resins could protect against erosion from acids. The objectives were to observe and quantify the effects of acids and the soft tissues, especially the tongue, on dentine and the bonding agents using four assessment techniques: qualitative assessment with SEM, surface roughness and thickness of resin with the TSM and volume loss with the laser profilometer.

DESIGN

An in situ investigation using extracted dentine sections embedded in splints held on the palate of 10 volunteers. The dentine sections were protected by two resins and subjected to a tooth wear regime.

RESULTS

Both Seal and Protect and Opitbond Solo protected the tooth surfaces from a tooth wear regime. There were no statistical differences between the control surfaces and those protected with dentine bonding agents for resin thickness, roughness and profilometry. The appearance of the slabs under both confocal and SEM showed that the material remained in place despite a vigorous wear regime and therefore protected the tooth surface.

CONCLUSIONS

For patients with uncontrolled erosion or tooth wear, applying a dentine bonding agent to exposed dentine is a practical option to prevent further damage.

Direct Core Materials

There are many materials that can be used for direct-placement cores. Although the scientific evidence is incomplete, some materials are better suited to this task than others. This article provides an overview of direct-placement core materials and highlights what clinicians should consider when assessing a new product.

Team training at an outreach dental unit

A cohort of eighty nine undergraduate dental students worked for one year on two clinics completing a total of 3901 days work. Most of this time (63%) was spent at a site with shared nursing support, but despite this another site with dedicated nursing support produced approximately the same output. Students and nurses preferred working as a team rather than sharing; 98% of the students completed a questionnaire on the role of dental nurses and the majority identified chairside assistance as being the most important contribution to the increased throughput of patients.

Safety issues when using carbamide peroxide to bleach vital teeth--a review of the literature

Hydrogen Peroxide is used to bleach discoloured teeth but since its introduction in the late nineteenth century there have been concerns about its safety and efficacy. This paper reviews the literature on hydrogen peroxide and carbamide peroxide and assesses if these products can be recommended for clinical use. The authors used a Medline search to find the literature for review and from these the findings were divided into laboratory, animal and human studies. In conclusion no dental treatment is without risk but from the evidence it seems that bleaching teeth is comparatively safe.

Evaluation of the pH of a new carbonated soft drink beverage: an in vivo investigation

PURPOSE

Recently, a modified version of a successful soft drink has been developed that aims to reduce the potential for dental erosion in consumers. The aim of this investigation was to compare the effect of the modified and original formula soft drink on the pH at various tooth surfaces during and after ingestion in subjects without erosion.

MATERIALS AND METHODS

Fifteen subjects (10 female and 5 male) without dental erosion drank both a modified and an unmodified beverage for over 5 minutes in a randomized order. Oral pH was measured with antimony electrodes positioned on the labial and palatal surfaces of an incisor and premolar and held in place by a close-fitting vacuum-formed appliance. The results were compared (using the Wilcoxon signed rank test, with matched pairs) for the percentage and total time that pH fell below 4, 5, and 5.5.

RESULTS

The percentage and total time that pH fell below 4 was significantly different between the drinks (P <0.02), but the total time that pH fell below 5 and 5.5 was not. The time taken for subjects to return to pre-exposure pH levels in the mouth showed considerable variation between individuals.

CONCLUSIONS

The modified-formula drink appeared to have less erosive potential than the original formula when assessed by measuring pH at the tooth surface. Although the erosive potential has been reduced by modifying the soft drink, it has not been eliminated.

Retrospective long term monitoring of tooth wear using study models

OBJECTIVE

Tooth wear is recognised as a common feature of European dentitions. However, little is known about its progression in susceptible patients. The aim of this study was to assess the degree and progression of tooth wear in patients by examining study casts taken of their teeth on two separate occasions.

DESIGN

Over 500 sets of study casts taken during an 18-year period from patients referred for a variety of restorative procedures, were examined at Guy's Dental Hospital. Of these, 34 cases were found to have consecutive models taken at two time intervals and these were used to assess the progression of tooth wear. Study models from 19 females and 16 males, with an average age of 26 years (range 18-60) at the time of their first presentation and were all examined by a single operator. The Smith and Knight tooth wear index was used to assess the degree of tooth wear at presentation and then at another time which was a median of 26 months (interquartile range 14 - 50 months) later.

RESULTS

The most common initial TWI score per surface was 1, with 54% of surfaces affected at the first assessment and 57% at the second. Score 2 was less common (14% at both assessments) and the scores for 3 and 4 combined were relatively uncommon with 5% of surfaces effected. Minimal progression of tooth wear was observed on study casts with only 7.3% of surfaces involved.

CONCLUSION

In this sample, tooth wear was a slow, minimally progressive process.

Direct cores for vital teeth--materials and methods used to retain cores in vital teeth

A core, or foundation restoration, is used to restore extensively damaged teeth to a form suitable for crown preparation. This literature review considers the range of materials which can be used for cores and the evidence for their suitability. The methods for their retention in vital teeth will be presented and appraised.

The suitability of head-of-implant and conventional abutment impression techniques for implant-retained three unit bridges: an in vitro study

This study compares the accuracy of master casts produced from impressions of implants using an abutment or a head-of-implant technique. The method used a Tandem Scanning Confocal Microscope to measure the dimensions of the gap between master casts produced by the two impression techniques and a custom made bridge. The median gap of 14 microns (interquartile range 10-17.9 microns) on the non-screwed side of the abutment impression was greater than the median gap of 7.5 microns (5-17.6 microns) for the head-of-implant impression and this difference was statistically significant (P < 0.005). In addition, the median gap on the screwed down side of the abutment impression of 10 microns, (6.3-12.1 microns) was greater than that of the head-of-implant of 5.5 microns (0.0-8.0 microns) and this difference was also statistically significant (P < 0.001). The head-of-implant impression produced a more accurate fit than the conventional abutment impression.

Comparison of the erosive potential of gastric juice and a carbonated drink in vitro

The aim of this study was to compare the erosive effect of gastric juice and a carbonated drink on enamel and dentine by measuring release of calcium from 30 hemisectioned teeth in vitro. In addition, the titrable acidity (mL of 0.05 M sodium hydroxide required to neutralize) and pH of the fluids was estimated. The mean pH of the seven gastric acid samples was 2.92 (range 1.2-6.78) and mean titratable acidity 0.68 mL (range 0.03-1.64). Both the pH and the titratable acidity of the gastric juice varied between patients all of whom suffered from symptoms of reflux disease. The carbonated drink had a pH of 2.45 and a titratable acidity of 0.29 mL. The median amount of calcium released by the gastric acids from enamel was 69.6 microg L-1 (interquartile range 5.4-144) and 62.4 microg L-1 (2.2-125.3) from dentine. The carbonated drink released 18.7 microg L-1 (13.4-23.4) and 18.6 microg L-1 (11.9-35.3), respectively. The differences in calcium release by gastric juice and the carbonated drink were statistically significant for both enamel (P < 0.005) and dentine (P < 0.01). It is concluded that gastric juice has a greater potential, per unit time, for erosion than a carbonated drink.

Bleaching discoloured teeth

The bleaching of teeth has encountered some legislative problems over the past few years but it is now possible to use both vital and non-vital bleaching techniques in the UK. Hydrogen peroxide has a long history of use and would appear to be safe to use to change the appearance of discoloured teeth. It is conservative of tooth tissue and may delay the need for more invasive veneers and crowns. This article describes some of the methods of bleaching using hydrogen peroxide that are currently available.

Experiences and perceptions of vocational training reported by the 1999 cohort of vocational dental practitioners and their trainers in England and Wales

OBJECTIVE

To assess the self-reported confidence of vocational dental practitioners (VDPs) in clinical procedures together with vocational trainers' perceptions of the VDPs confidence in the same procedures, immediately after qualification and towards the end of the vocational training year.

DESIGN

A questionnaire-based cohort study.

SETTING

A general practice study carried out in 1999.

SUBJECTS

Vocational Dental Practitioners and vocational trainers in England and Wales.

METHOD

VDPs and trainers were asked on a single occasion to grade the clinical confidence of the VDP at the beginning and near the end of vocational training as high, satisfactory or low.

RESULTS

Questionnaires were sent to 531 VDPs and 555 trainers; 82 per cent of VDPs and trainers responded. Approximately half the VDPs were male and 57 per cent were white, whilst 89 per cent of trainers were male and 81 per cent white. A large proportion of both VDPs and trainers reported low confidence in orthodontics, molar endodontics and surgical extractions at the start of the training year. Towards the end of training, both groups reported improved confidence levels in most clinical procedures. However, a higher proportion of trainers reported low confidence than their VDPs in most clinical procedures at both time points (p<0.001). VDPs appeared to gain most from experience and training in administration/management and interpersonal skills.

CONCLUSION

Vocational training appears to satisfy its aim to enhance clinical and administrative confidence.

The measurement and prevention of erosion and abrasion

OBJECTIVES

To develop a reproducible method to measure tooth wear and assess the protection given by dentine bonding agents in an erosive/abrasive wear regime.

METHODS

Seal and Protect (Dentsply, UK) and Optibond Solo (Kerr, UK) were each applied to 20 extracted teeth and subjected to 3000 cycles in a reciprocating erosion/abrasion wear machine. A further 20 teeth, without protection, were subjected to the same wear regime and were either brushed in water or immersed in acid. Impressions were taken by a standardised technique and were scanned with a non-contacting laser profilometer. The amount of erosion was measured at the same co-ordinates before and after erosion using 2mm diameter metal discs as reference points.

RESULTS

The amount of wear on Seal and Protect had a mean 24.8 microm (SD 57.4 microm) and for Solo it was 1.4 microm (24.5 microm), and this difference was statistically significant (p=0.02). There was no statistically significant difference in the wear measured on the teeth brushed in water or immersed in acid. The wear measured on the unprotected teeth was 243 microm (SD 120 microm) and was statistically significantly different to the protected surfaces (p=0.001).

CONCLUSION

Both Seal and Protect and Solo protected the teeth in this wear regime and the technique could be used clinically for patients with uncontrolled dental erosion.

Mesotrione: a new selective herbicide for use in maize

Mesotrione is a new herbicide being developed for the selective pre- and post-emergence control of a wide range of broad-leaved and grass weeds in maize (Zea mays). It is a member of the benzoylcyclohexane-1,3-dione family of herbicides, which are chemically derived from a natural phytotoxin obtained from the Californian bottlebrush plant, Callistemon citrinus. The compound acts by competitive inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), a component of the biochemical pathway that converts tyrosine to plastoquinone and alpha-tocopherol. Mesotrione is an extremely potent inhibitor of HPPD from Arabidopsis thaliana, with a Ki value of c 6-18 pM. It is rapidly taken up by weed species following foliar application, and is distributed within the plants by both acropetal and basipetal movement. Maize is tolerant to mesotrione as a consequence of selective metabolism by the crop plant. Slower uptake of mesotrione, relative to susceptible weed species, may also contribute to its utility as a selective herbicide for use in maize.

Mesotrione: a new selective herbicide for use in maize

Mesotrione is a new herbicide being developed for the selective pre- and post-emergence control of a wide range of broad-leaved and grass weeds in maize (Zea mays). It is a member of the benzoylcyclohexane-1,3-dione family of herbicides, which are chemically derived from a natural phytotoxin obtained from the Californian bottlebrush plant, Callistemon citrinus. The compound acts by competitive inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), a component of the biochemical pathway that converts tyrosine to plastoquinone and alpha-tocopherol. Mesotrione is an extremely potent inhibitor of HPPD from Arabidopsis thaliana, with a Ki value of c 6-18 pM. It is rapidly taken up by weed species following foliar application, and is distributed within the plants by both acropetal and basipetal movement. Maize is tolerant to mesotrione as a consequence of selective metabolism by the crop plant. Slower uptake of mesotrione, relative to susceptible weed species, may also contribute to its utility as a selective herbicide for use in maize.

A literature review of the techniques to measure tooth wear and erosion

This paper reviews methods to measure tooth wear especially those more recently introduced as a result of improvements in technology. The review searched methods to measure tooth wear and dental erosion from large epidemiological investigations, in vitro and in vivo studies. There seems to be wide variation in techniques used to measure tooth wear and erosion. In vitro techniques may have little direct clinical relevance but can lead to new and more accurate clinical methods. In vivo studies have problems with reference points and accurate validation of the techniques. There is a need for a simple, reliable technique to quantify tooth wear due to erosion.