Lingual Surfaces Of Teeth Research Articles

A comparison of debonding strengths of four metal-ceramic systems with and without opaque porcelain

When performing an adjustment on metal-ceramic restorations, opaque porcelain may become exposed, particularly on the lingual surface of maxillary anterior teeth. It is generally believed that exposed opaque porcelain can be more abrasive and destructive to an opposing dentition than body porcelain, and that these teeth may require restoration as a consequence. This study compared the debonding strengths of 2 types of porcelain, with and without opaque porcelain, to 2 types of dental casting alloys. Two porcelain systems, Ceramco3 and Vita 900, and 2 metal alloys, a high noble (Encore) and a base metal (Duceranium U), were used to fabricate and test 56 flexure bars in accordance with ISO 9693:1999(E): Metal-Ceramic Dental Restorative Systems. Half of the bars received opaque porcelain prior to body porcelain additions, and the other half did not. The metal-ceramic debonding strength was determined by using a 3-point flexure apparatus and a mechanical testing device (Instron). A center load was applied at a crosshead speed of 1.5 mm/min(-1) until debonding occurred. In addition to the load-versus-displacement curve, a precision measurement microphone was used to assist in ascertaining the point in time when debonding occurred. Since the sound analysis and the mechanical test were started simultaneously, the debonding load could be more accurately determined. Data were statistically analyzed using 3-way analysis of variance, and all pairwise multiple comparisons were made with the Tukey HSD test (alpha=.05). The difference in mean debonding strength values for opaqued and non-opaqued flexure bars were statistically significant (P=.028). The mean debonding strength values (MPa) for each metal-ceramic system were as follows: Encore-Opaque-Ceramco3 (EOC), 31.43 +/- 6.92(a); Encore-Opaque-Vita 900 (EOV), 30.37 +/- 3.25(a); Duceranium U-No Opaque-Ceramco3 (DNC), 29.20 +/- 6.97(a); Duceranium U-Opaque-Ceramco3 (DOC), 26.61 +/- 4.98(a); Duceranium U-Opaque-Vita 900 (DOV), 26.15 +/- 4.29(a); Encore-No Opaque-Vita 900 (ENV), 25.45 +/- 4.04(a); Encore-No Opaque-Ceramco3 (ENC), 23.96 +/- 4.14(a); Duceranium U-No Opaque-Vita 900 (DNV), 22.88 +/- 6.15(a). Identical superscript letters denote no significant difference among groups. The precision measurement microphone resulted in selection of a debonding strength/crack initiation load that was lower than the peak load recorded during strength testing. Initial debonding during crack initiation strength testing may not always correspond to the peak load recorded, but rather to the point on the load-versus-displacement curve beyond which the relationship is no longer a straight line. Presence of opaque porcelain generally increased the debonding strength for metal-ceramic systems; however, opaque porcelain may not be necessary for a clinically acceptable metal-ceramic bond for some metal-ceramic systems.

Physiological properties of molar-mechanosensitive periodontal neurons in the trigeminal ganglion of the rat

Spike discharges from periodontal mechanosensitive neurones responding to the mechanical stimulation of molar teeth were recorded from the trigeminal ganglion of rats anaesthetized with pentobarbital sodium. Maxillary molar-sensitive units were close together in a narrow, lateral area of the maxillary division of the ganglion, whereas those of mandibular molar-sensitive units were scattered throughout the mandibular division. The majority of maxillary molar-sensitive units responded only to stimulation of the first molar. They were slowly adapting and responded most strongly to pressure applied to the lingual surface and buccal cusp of the tooth or to the buccal surface and lingual cusp. By contrast, approximately one-half of the mandibular molar-sensitive units were rapidly adapting, multitooth units that responded to tooth stimulation almost equally in all directions. The other half were slowly adapting and activated most effectively by pressure applied to the lingual surface and buccal cusp of the molar tooth. These slowly adapting units consisted of first molar-sensitive, single- and multitooth units. Differences in the response characteristics of the maxillary and mandibular molar-sensitive periodontal units may reflect differences in the sensory role of individual molars.

Periodontal Status in Patients With Gingival Mucous Membrane Pemphigoid

Mucous membrane pemphigoid (MMP) describes an autoimmune disease with a range of variants, including those with oral, ocular, and cutaneous lesions. Persistent oral lesions, lack of effective oral hygiene, and plaque accumulation may increase the risk of long-term periodontal disease. However, to our knowledge, no studies have evaluated the relationship between the presence of gingival MMP and periodontal health. The purpose of this study was to evaluate the possible impact of gingival pemphigoid lesions on the human periodontium. Twenty patients with histologic confirmation of subepithelial separation with or without direct immunofluorescence testing were randomly chosen to participate in a study evaluating their periodontal status. Parameters evaluated included plaque score, gingival index, bleeding index, probing depths, recession, clinical attachment level, mobility, furcation involvement, number of missing teeth, and Machtei criteria, a previously defined criteria for periodontitis. Individuals matched with respect to age, gender, and smoking history were selected and evaluated for the same parameters. MMP patients had statistically significant larger mean gingival index scores than age, gender, and smoking history matched controls. Plaque scores, bleeding index, mobility, furcations, clinical attachment level, recession, and periodontal status did not show statistically significant differences between MMP and control patients. A statistically significant difference in plaque index was found when patients with MMP in treatment were compared to patients with MMP in remission. Among patients with MMP, those diagnosed >5 years in the past had statistically significantly greater Class I furcation involvement and recession on facial and lingual surfaces of teeth. A relationship was found to suggest that patients with MMP exhibit more gingival inflammation than a control population. Among patients with MMP, patients currently in treatment have higher plaque indices than those in remission and not receiving treatment. Furthermore, when comparing patients with MMP who received a diagnosis>5 years in the past to those with a diagnosis in the past 5 years, statistically significantly greater Class I furcation and facial and lingual recession were measured. Long-term follow-up in this population may provide additional information as to periodontal progression in MMP versus control patients.

An unusual case of talon cusp on a geminated tooth

Talon cusp is a developmental anomaly seen on the lingual surface of anterior teeth. Gemination is an anomaly caused by a single tooth germ that attempted to divide during its development. These developmental anomalies may cause clinical problems including esthetic impairment, pain, caries and tooth crowding. This paper presents an unusual case of gemination accompanied by talon cusp in permanent dentition. The clinical and radiographic findings are described.

Effects of buccal versus lingual surfaces, enamel conditioning procedures and storage duration on brackets debonding characteristics

To determine the influence of two enamel conditioning techniques on buccal and lingual tooth surfaces at two different times on debonding strength and tooth damage. The study included 50 premolars. Buccal and lingual surfaces of 10 teeth were scanned using SEM before (N=4) and after enamel conditioning by either acid etching or sandblasting prior to acid etching (N=6) for their morphology. The remaining 40 teeth were divided into 2 equal groups, differing in enamel conditioning prior to metallic bracket bonding on the buccal and lingual surfaces. Each group was equally subdivided into short-term (48h) or long-term (12m) water storage. Debonding strength was measured followed by SEM and EDAX for adhesive remnant index (ARI) and calcium remnant index (CRI) left on bracket bases. ANOVA with repeated measures was applied to the results. The buccal enamel was rougher than the lingual one. The surface morphology after the two types of conditioning showed a different pattern. A significantly higher debonding strength was needed to debond the buccal brackets compared to the lingual ones (p<0.05). A significantly higher ARI (p<0.002) and higher CRI (p<0.005) were found in the lingual surface compared with the buccal. No differences were found in debonding strength ARI or CRI regarding the different conditioning or storage duration. Lingual bonding leads to higher ARI and CRI than buccal bonding. Sandblasting prior to etching does not improve bonding strength for lingual or buccal bonding.

The Bacteriology of the Supragingival Plaque of Child Dental Patients in Kuwait

Objective: To investigate the bacterial flora of the gingival plaques of pediatric dental patients in order to establish baseline data for future studies on the complex microbiota of the oral cavity of this group of child dental patients. Subjects and Methods: Forty subjects, aged 3–12 years, were enrolled and investigated after informed consent was obtained. During the patients’ first visit to the dental clinic supragingival plaque samples were collected from the gingival area of buccal and lingual tooth surfaces of all primary and permanent molar teeth using sterile curettes. Serially diluted samples were inoculated onto a set of selective and nonselective media and then incubated at the appropriate atmospheric conditions and temperatures. Representative colonies of isolates were identified by standard methods, including hemolytic characteristics on blood agar and profiling on API 20S and API 20A as appropriate. Results: A total of 183 isolates (123 aerobes and 60 anaerobes) were recovered from the 40 patients with a mean count of 3 per sample of aerobes compared to 1.5 per sample for the anaerobes. Streptococcus sanguis was the predominant aerobic species (23.6%) isolated from 29 (72.5%) of the 40 patients, followed by Streptococcus mitis, 19.5 and 60%, Streptococcus salivarius, 17.1 and 52.5% and Streptococcus mutans, 17.1 and 52.5%. The frequency of isolation of anaerobic bacteria was Prevotella spp. 50% from 30 (75%) of the 40 patients, Fusobacterium spp., 18.3 and 27.5%, Bacteroides spp., Porphyromonas spp. and Peptostreptococcus spp., 6.7 and 10%, 6.7 and 10%, and 5 and 7.5%, respectively. Prevotella intermedia was the single most common species. Conclusion: The results show that there were more aerobic/facultative anaerobic bacteria than the obligate anaerobes in the dental plaque of the pediatric dental patients in Kuwait. The high prevalence of the pioneering streptococci as well as black-pigmented Prevotella spp. and Fusobacterium spp. indicates that the dental plaques of the children were in the developing stage, a precursor to the development of periodontal diseases.

A new microsaur (Tetrapoda: Lepospondyli) from the Lower Permian of Richards Spur (Fort Sill), Oklahoma

Bolterpeton carrolli n.gen. n.sp. is described from the Lower Permian fissure-fill deposits of Richards Spur, Oklahoma. Bolterpeton is united with the gymnarthrid microsaur Cardiocephalus by having teeth compressed labiolingually, a narrow anterior process of the prearticular penetrating the splenial, and the arrangement of the contacts among the splenial, prearticular, and coronoids. It is united with both Cardiocephalus and Euryodus by the size and distribution of the coronoid teeth and the presence of longitudinal striations of enamel on the lingual tooth surface. Unlike those two genera Bolterpeton has peg-like teeth, but it remains unknown whether this represents the primitive condition or a reversal of the massive conical teeth typical of gymnarthrids. Bolterpeton possesses a flat lamina that runs along the lingual surface of the tooth margin. Where two laminae meet at the point of the tooth a labiolingual ridge is formed, which is most pronounced at smaller sizes. Reexamination of Cardiocephalus shows it to have the same morphology on its "incisors." Previous authors have defined teeth bearing this ridge as "weakly bicuspid." If this ridge were homologous with the "strongly bicuspid" condition of lissamphibians, Bolterpeton would provide the first example of this tooth morphology in lepospondyls and would strengthen recent hypotheses suggesting lepospondyls gave rise to some, if not all, modern amphibians.

Percent of plaque on individual tooth surfaces and differences in plaque area between adjacent teeth in healthy adults

To apply a planimetric method to determine the percentage of the tooth area covered by plaque on individual tooth surfaces and to compare the percentage of plaque between adjacent tooth surfaces. Forty-three adults, mean age 43.0 years, with no signs of periodontal disease, participated. The subjects underwent comprehensive professional cleaning of all teeth. The subjects were then instructed to maintain their ordinary oral hygiene habits. Plaque was registered after 1 month, on each individual tooth surface by use of P%I. The pattern of plaque accumulation was in large symmetrical, with differences in mean P%I between several adjacent tooth surfaces, e.g. for the maxillary buccal and lingual tooth surfaces between the first and second molars (P<0.001) and for the lingual tooth surfaces between the canines and the first premolars (P<0.01). In the present study, it was possible to identify and describe adjacent tooth surfaces with the most pronounced plaque accumulation, to make further improvements of oral hygiene possible.

Sites of dental erosion are saliva-dependent.

Acid demineralization of teeth causes occlusal erosion and attrition and associated non-carious cervical lesions at sites relatively unprotected by saliva. Associations of occlusal pathology and cervical lesions were looked for in 450 patients with toothwear, and 174 subjects with cervical lesions were identified. Associations of occlusal attrition, or erosion, or no wear, with cervical lesions at 72 buccal and lingual sites were recorded from epoxy resin replicas of the subjects' dentitions (3241 teeth). Criteria used to discriminate occlusal erosion from attrition; and shallow from grooved and wedge-shaped cervical lesions were delineated by scanning electron microscopy (SEM). In the absence of occlusal pathology, cervical lesions were very rare (<1%). In the presence of occlusal pathology, cervical lesions were present in 27.71% of buccal sites as opposed to 2.61% of lingual sites. The commonest site of cervical lesions was the facial of maxillary incisors (36% of sites). The least common site was the lingual aspect of mandibular molars (1.7% of sites). These differences may reflect the normal protective role of serous saliva and salivary pellicle in a site-specific manner, on the lingual surfaces of mandibular teeth particularly, and do not support abfraction as the prime aetiology of cervical lesions.

Plaque pH and Associated Parameters in Relation to Caries

Intensified plaque acidogenicity in caries–prone subjects was reported many years ago, but emerging evidence has suggested that the relationship may not be as strong as once thought. We have now determined a range of acidogenicity variables in subjects having both caries prevalence and incidence data, and have included plaque mineral data in the analysis. pH measurements were made in 20 randomly selected subjects from a high–caries group (mean DMFS = 8.95) and 20 from a caries–free group of Beijing children aged 12 years participating in a caries prediction study. Subgroups with a 12–month DMFS increment ≥2 or = 0 were also formed from the two groups, respectively. Measurements were made with an iridium oxide electrode inserted between teeth 13/14, 23/24, 34/35 and 44/45, before and every 5 min for 30 min after rinsing with 10% sucrose, and the 4 resulting ‘Stephan curves’ averaged using a plaque pH analysis program. Supragingival plaque was collected from buccal and lingual smooth surfaces of posterior and upper anterior teeth and its acid extract analysed for Ca, P and F. Caries–free subjects (based on past experience) had a significantly higher maximum plaque pH and pH value after 30 min (reflecting a faster return to resting pH), a lower minimum enamel dissolution capacity of plaque and recorded less time below pH 7.0 than did high–caries subjects. No other differences were significant, including those of the principal acidogenic parameters ‘minimum pH attained after a sugar rinse’, ‘curve area below the critical pH of 5.5’ and ‘time below the critical pH’. Selection of the caries groups on the basis of both experience and incidence did not reveal significant differences in more parameters. Upper arch plaque was significantly more acidogenic than lower arch plaque, and there was a consistently strong association between upper and lower arch values in individuals. Ca, P and F in the subjects’ plaque had little or no influence on the principal acidogenic parameters. Our failure to find a relationship between caries prevalence or activity and these principal acidogenicity parameters may be related to differences between fissure and smooth surface plaque, temporal variations in acidogenicity and/or to use of F toothpaste during the 1–year observation period. These results support the view that factors such as the frequency of acidogenic episodes may be more important in caries progression than the degree of acidogenicity during any one episode.

Human Enamel as a Substrate for in Vitro Acid Dissolution Studies: Influence of Tooth Surface and Morphology

The variation in susceptibility of enamel to acid dissolution has been quantitatively assessed in vitro by examination of different surfaces of both maxillary and mandibular teeth of different morphology obtained from a pool of sound human teeth. The lingual/palatal surfaces of all teeth showed greater susceptibility to acid dissolution than the corresponding labial/buccal surfaces. The palatal surface of the maxillary teeth appeared more susceptible to acid than the lingual surface of the corresponding teeth in the mandible. The palatal surfaces of the maxillary teeth showed least variation in acid susceptibility, whilst the lingual surfaces of mandibular teeth and buccal/labial surfaces of teeth from both jaws showed much more variation between teeth of different morphology. These differences in susceptibility to acid dissolution probably reflect both developmental differences and post-eruptive changes in enamel and may contribute to the clinical presentation of dental disease. Importantly, the data indicates that careful selection of teeth for in vitro study of enamel dissolution processes is essential to minimise inter-sample variation. For such purposes, the palatal surface of the maxillary teeth appears to be most suitable.

PRISMLESS ENAMEL IN HUMAN NON-ERUPTED DECIDUOUS MOLAR TEETH: A SCANNING ELECTRON MICROSCOPIC STUDY

The frequency, structure and thickness of the prismless enamel layer in the buccal and lingual surfaces of non-erupted deciduous molar teeth were described. The teeth were extracted, kept in a 70% ethanol solution, dried, coated with gold and examined in a scanning electron microscope JEOL, JSM-6.100. The aprismatic layer was observed in the occlusal, middle and cervical thirds of all buccal and lingual surfaces. The hydroxyapatite crystals were arranged parallel to each other and perpendicular to the enamel surface. No statistically significant differences were observed between the occlusal, middle and cervical thirds, which had 7.257 &lt;FONT FACE="Symbol"&gt;m&lt;/FONT&gt; m of average thickness.

The effect of a vital bleaching technique on enamel surface morphology and the bonding of composite resin to enamel.

This study examined the effect of a nightguard vital bleaching procedure on enamel surface morphology and the shear bond strength of a composite resin luting cement to enamel. Extracted human teeth were bleached for 1 week using a vital bleaching product. Control teeth were brushed with a fluoride toothpaste and processed similarly to the bleached teeth, however the bleaching product was substituted with artificial saliva in the night guards. Teeth were stored in artificial saliva for 24 h, 1, 6 or 12 weeks and then examined for any surface changes using light and scanning electron microscopy. The effect of etching surfaces with 37% phosphoric acid was examined at the scanning electron microscope level. The shear bond strength of composite resin luting cement to both buccal and lingual surfaces of bleached and control teeth was determined. Light microscopy investigation suggested the bleaching process resulted in a loss of mineral from enamel which was evident 24 h after bleaching and was sustained following 12 weeks storage in artificial saliva. Scanning electron microscopy showed a definite change in the surface texture of the bleached enamel surface. Acid etching of the bleached enamel surface produced loss of prismatic form and the enamel appeared overetched. The mean shear bond strength between composite resin luting cement and etched enamel tended to be lower for bleached enamel surfaces, however no significant difference in shear bond strength was noted between control and experimental groups. The results of this study suggest that bleaching resulted in changes to the surface and subsurface layers of enamel. Although surface changes were observed in the etched enamel, the shear bond strength of composite resin luting cement to etched bleached enamel appeared to be clinically acceptable.

Influence of tooth cryopreservation and storage time on microleakage

Objectives. This study was conducted to compare microleakage of two new dentin bonding agents on freshly extracted teeth, cryopreserved teeth, or teeth stored in water containing 0.5% chloramine at 4°C. Methods. Rectangular Class V cavity preparations were made on the buccal and the lingual surface of wisdom teeth. They were filled with either Scotchbond Multi-Purpose and Z100 (3M Dental Products) or with Gluma 2000 and Pekafill (Bayer Dental). After thermocycling, silver staining penetration was evaluated under a light microscope. SEM examination and EDX analysis were performed to evaluate the microleakage pattern. The results were analyzed by the use of a two-way analysis of variance. Results. Cryopreservation for 13 wk or 12 d refrigeration did not produce changes in the amount of microleakage. However, 48 d or longer of refrigeration increased microleakage. There was no correlation between changes in microleakage and storage time. Specimens prepared with both dentin bonding agents exhibited the same microleakage values and the same microleakage pattern. Significance. Refrigeration at 4°C in 0.5% chloramine for 48 d or longer may cause an increase in microleakage. Cryopreservation for 13 wk or short-term refrigeration did not affect the microleakage.

Effects of mandibular nerve block on heat‐ or cold‐induced changes in pulpal blood flow in man

Laser Doppler flowmetry (LDF) was used to study the effect of mandibular nerve block, using 3% mepivacain, on heat- or cold-induced changes in pulpal blood flow (PBF) evoked by application of cold or heat to the lingual surfaces of teeth 33 and 43 in nine young subjects. PBF on average showed a 7% increase in response to heat (48 degrees C) and a 20% decrease when exposed to cold (3 degrees C). Neither response was affected by mandibular block. From this we concluded that the effects on PBF of the presently applied heating and cooling of the tooth were solely due to direct thermal influences on the blood vessels, without involvement of vasomotor or sensory nerves.

SEM characterization of the resin-dentine interface produced in vivo

Objectives: A freeze-fracture technique with critical-point drying has been shown to preserve the structure of collagen in demineralized primed dentine in vitro (Titley K et al. Am J Dent 1994; 7: 22–26). This study utilized the technique to examine the attachment to dentine produced in vivo by All-Bond 2 (AB2), Scotchbond Multi-Purpose (SBMP) and Prisma Universal Bond 3 (PUB3). Methods: Eighteen medium-depth restorations were placed in buccal and/or lingual surfaces of premolar teeth ( n = 7) scheduled for extraction for orthodontic purposes. After extraction, the restored teeth were split transversely by freeze-fracture, critical-point dried and examined under SEM. Results: AB2 and SBMP produced significant gap-free attachment to dentine showing similar microscopic structural features. Resin interdiffusion with collagen fibrils of the intertubular matrix was clearly seen. Microspaces, observed at the periphery of the widened tubules and among the interdiffused collagen fibrils, suggested incomplete resin penetration. Fractures occurring parallel with the interface frequently showed detachment in the deepest layers of the hybrid zone. Adhesive gaps were seen at the resin-dentine interface, indicating some clinical technique failure. The PUB3 attachment was generally incomplete, with separation between the primed dentinal surface and the composite restoration. Where present, the bonded interface showed no evidence of true hybridization. Conclusion: Dentine conditioning, as a separate step, prior to priming, appears to be an important factor in successful resin-dentine attachment. Critical-point drying revealed variations in the degree of resin interdiffusion with intertubular collagen, suggesting potential sites for bond failure.

Assessment of tooth wear in an ageing population

A random sample of 2222 adults aged 45 years and over was taken from the age/sex registers of two general medical practices in Newcastle upon Tyne, and asked to take part in a dental health survey. A total of 1002 individuals agreed to take part and were visited in their homes. Five hundred and eighty-six subjects were dentate and able to undergo an assessment of tooth wear using the Tooth Wear Index (TWI). Increasing wear with increasing age was observed for all cervical and occlusal/incisal tooth surfaces. Occlusal/incisal surfaces displayed some of the highest mean wear scores, especially in the older age cohorts. With the exception of lingual surfaces of maxillary anterior teeth, no significant variation in tooth wear with age was noted for buccal or lingual surfaces. Greater mean wear scores were observed among males than females, but there was little variation between subjects of different social class backgrounds. The threshold levels of wear suggested for use with the TWI may require modification for use among elderly populations.

The Use of Ceramic Orthodontic Brackets as Rest Seats for Removable Partial Dentures

Ceramic orthodontic brackets were developed for the purpose of esthetics and increased tooth-to-bracket strength. An alternative method of preparing a rest seat on the lingual surface of lower canine teeth without violating the enamel integrity is offered. Ceramic orthodontic brackets were bonded to the lingual surfaces of mandibular canines and shaped into rest seats using diamond burs. Because the rest seats are not cut into the tooth structure, sensitivity and potential caries complications are avoided. The bracket is adhered to the tooth surface with a dimethacrylate bonding material. The brackets are bonded with either a no-mix or a two-part adhesive system. The strength of this bond will easily support the forces of a partial denture framework. The advantage over metal acid-etched retained rests is that this method avoids a time-consuming laboratory step. The greatest advantage over the use of composite resins that are shaped into rest seats is the much higher bond strength. After ceramic brackets were bonded to the lingual surfaces of mandibular canines and shaped into rest seats, an impression was obtained for the fabrication of a conventional partial denture framework.

Evidence from tooth surface morphology for a posterior maxillary origin of the proteroglyph fang

Abstract Although the front-fanged venom delivery system of the Elapidae is believed to be derived from an aglyphous or opisthoglyphous colubroid ancestor, opinion is divided as to the end of the maxilla on which the proteroglyph fang originated. This study was undertaken to determine whether the evolutionary precursor of the proteroglyph fang was (a) a grooved posterior fang which migrated anteriorly, or (b) an enlarged anterior tooth which secondarily developed a groove for the conduction of venom. The surface morphology of the maxillary teeth of colubrid genera was examined using scanning electron microscopy. Ridges present on the lingual and labial surfaces of anterior maxillary teeth and on the anterior and posterior surfaces of posterior maxillary teeth were identified as morphological markers of potential value in distinguishing the anterior and posterior maxillary teeth of colubrid snakes, and in determining the origin of the proteroglyph fang. Patterns of ridges on the surfaces of elapid fangs examined were found to be consistent with the hypothesis that the evolutionary precursor of the proteroglyph fang was an opisthoglyph fang which migrated anteriorly.

Bond strength to dentine of two light-activated glass polyalkenoate (ionomer) cements

The effects of sample thickness on the in vitro bond strength of two light-activated glass polyalkenoate cements to dentine have been investigated. The buccal and/or lingual surfaces of non-carious human third molar teeth were used for bonding. The tensile bond strengths to dentine of samples of the cements of 0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm were measured 10 min after bonding. For one of the materials bond strength and reliability were found to decrease as the sample thickness increased. The bond strength to dentine of the second material was also affected by changes in the thickness of the cement but as the bond strengths were all very low for this material, any differences are probably of little clinical relevance.