Impact of mucin on the anti-erosive/anti-abrasive efficacy of chitosan and/or F/Sn in enamel in vitro.

The application of stannous ions in combination with fluoride (F/Sn) is one of the central strategies in reducing erosive tooth wear. F/Sn efficacy can be enhanced by adding chitosan, a positively charged biopolymer. For patients with low saliva flow, this efficacy, however, is not sufficient, making further improvement desirable. This could be achieved by combining chitosan with other molecules like mucin, which together might form multilayers. This in-vitro study aimed to investigate the effect of chitosan, mucin, F/Sn and combinations thereof on enamel erosion and erosion-abrasion. Human enamel samples (n = 448, 28 groups) were cyclically eroded or eroded-abraded (10 days; 6 × 2 min erosion and 2 × 15 s/200 g abrasion per day). Samples were treated 2 × 2 min/day with solutions containing either, chitosan (50 or 500 mPas), porcine gastric mucin, F/Sn or combinations thereof after abrasive challenge. Tissue loss was measured profilometrically, interaction between hard tissue and active agents was assessed with energy dispersive spectroscopy and scanning electron microscopy. Chitosan and F/Sn showed the expected effect in reducing tissue loss under erosive and under erosive-abrasive conditions. Neither mucin alone nor the combinations with mucin showed any additional beneficial effect.

3D-Image analysis of the impact of toothpaste abrasivity on the progression of simulated non-carious cervical lesions.

OBJECTIVES: To investigate the effect of toothpaste abrasive level on the progression of non-carious cervical lesions (NCCLs) using 3D-image subtraction. METHODS: Upper first premolars were allocated into seven groups (n = 16) of toothpaste/abrasive slurries: A-Zeodent113/5%, B-Zeodent124/10%, C-Zeodent103/15%, D-Sensodyne Pronamel, E-Crest Cavity-Protection, F-Crest Pro-Health-Whitening, and G-Deionized water (DIW). Teeth were mounted on acrylic blocks, and their root surfaces covered with acrylic resin, except for 2-mm near the cemento-enamel junction that was exposed to toothbrushing. Specimens were brushed with the slurries for 5000-, 15,000-, 35,000- and 65,000-strokes. Impressions were taken at baseline and after each brushing time, and then scanned by a 3D optical profilometer. Dentine volume loss was calculated by image subtraction software and subjected to mixed-model ANOVA and multiple comparison tests (α = 0.05). RESULTS: No significant differences among slurries were observed at 5000 and 15,000. At 35,000, F showed higher loss than all other groups except C, which did not differ from the others. At 65,000, F (4.19 ±â€¯3.29 mm3) showed the highest loss, followed by C (2.33 ±â€¯1.47 mm3), which differed from all the other groups except B (1.85 ±â€¯0.91 mm3). Groups B, A (1.35 ±â€¯0.65 mm3), D (1.17 ±â€¯0.48 mm3), E (1.40 ±â€¯0.68 mm3) and G (1.12 ±â€¯0.73 mm3) did not differ from each other. Groups F and C showed significant increase of volume loss starting at 35,000, while B, A, D and E only at 65,000; no increase loss was observed for G. CONCLUSIONS: 3D-image subtraction was able to quantify and differentiate tooth loss, but only at advanced stages. The progression of NCCLs was more evident and faster for highly abrasive slurries. CLINICAL SIGNIFICANCE: Upon root dentin exposure, brushing with lower abrasive dentifrices is advisable to reduce the risk for NCCLs development.

Non-carious cervical lesions imaged by focus variation microscopy.

OBJECTIVE: The aim of this study is to characterize the morphological and histological features of NCCLs in a group of extracted teeth using a focus variation optical microscopic technique that is capable of detecting minute variation in surface topography. METHODS: Twenty three extracted teeth containing NCCLs were collected. Histological features of the surface and longitudinal cross sections were examined using a focus variation microscope (FVM). RESULTS: The sample included 8 teeth with wedge-shaped lesions; the remaining 15 contained saucer-shaped lesions. Wedge-shaped lesions showed obliterated dentinal tubules, parallel furrows and micro-fractures in the surface; longitudinal cross sections revealed subsurface micro-fractures extending toward the pulp chamber. The surfaces of typical saucer-shaped lesions were smooth and relatively featureless. CONCLUSIONS: FVM imaging shows microstructures that are consistent with simultaneous erosion and toothbrush abrasion. Saucer shaped lesions have a smooth featureless surface as well as craters and dimples that could be attributed to uneven acid attack. In wedge-shaped lesions, the presence of scratches and furrows could be attributed to mechanical forces such as tooth brush abrasion. The furrows and in-surface micro-factures of wedge shaped lesions suggest a possible role of tensile stresses but require further investigation. CLINICAL SIGNIFICANCE: NCCLs present in two morphologies, either saucer-shaped or wedge-shaped. Erosion and toothbrush abrasion are important in both types of lesions. Tensile stresses due to occlusal loading may be important in some wedge-shaped lesions. Knowing the etiology of cervical lesions is the key for their prevention.

A pilot study to assess the morphology and progression of non-carious cervical lesions.

OBJECTIVE: This longitudinal pilot study aimed to morphologically and quantitatively investigate the progress of non-carious cervical lesions (NCCLs) by using swept-source optical coherence tomography (SS-OCT). METHODS: The samples examined comprised sets of NCCL epoxy resin replicas obtained from 10 lesions in 6 patients who attended annual dental visits over 4 or 5 years. SS-OCT images of the replicas were analyzed in terms of the maximum depth (Dmax) and corresponding vertical width (VW) - using an image analyzer to estimate progression of the NCCLs over time. RESULTS: It was found that differences between wedge- and saucer-shaped lesions were morphologically distinguished well by the OCT images. There were significant differences in dimensions among Dmax, VW and horizontal width (HW). HW was the largest and Dmax was the smallest. Although no significant differences in absolute values of annual progression rates were found among Dmax, VW and HW, the percentage increase in Dmax was significantly greater compared to VW and HW. The ratios of Dmax to corresponding VW ranged from 0.49 to 1.01 for the wedge-shaped lesions and from 0.13 to 0.44 for saucer-shaped lesions, respectively. CONCLUSIONS: The dimensional analysis demonstrated notable progression with large variations. The wedge-shaped lesions appeared to show greater Dmax values compared to the saucer-shaped lesions. CLINICAL SIGNIFICANCE: With respect to the depth, the wedge-shaped lesions may progress at a greater rate compared to the saucer-shaped lesions.

In vitro Efficacy of Experimental Chitosan-Containing Solutions as Anti-Erosive Agents in Enamel.

The present study evaluated the effect of chitosans with different viscosities, dissolved in an AmF/SnCl2 solution, against erosion or erosion/abrasion. A total of 192 specimens were assigned to 2 × 6 groups (n = 16 specimens each): negative control, 4 chitosan solutions (groups Ch50, Ch500, Ch1000, and Ch2000, with viscosity of 50, 500, 1,000, or 2,000 mPas, respectively, 0.5% chitosan, 500 ppm F-, 800 ppm Sn2+, pH 4.4), and positive control (500 ppm F-, 800 ppm Sn2+, pH 4.3). One half of the groups was demineralized (experiment 1, E1; 10 days, 6 × 2 min/day, 0.5% citric acid, pH 2.8) and exposed to solutions (2 × 2 min/day); the other half was additionally brushed (15 s, 200 g) with non-fluoridated toothpaste before solution immersion (experiment 2, E2). Treatment effects were investigated by profilometry, energy-dispersive X-ray spectroscopy and scanning electron microscopy (SEM). In E1, all the chitosan-containing solutions reduced enamel loss by 77-80%, to the same extent as the positive control, except for Ch2000 (p ≤ 0.05), which completely inhibited tissue loss by the formation of precipitates. In E2, Ch50 and Ch500 showed best performance, with approximately 60% reduction of tissue loss compared to the negative control group (p ≤ 0.05 compared to other groups). SEM analysis showed differences between negative control and the other groups but only minor differences amongst the groups treated with active agents. In both E1 and E2, treatment with active agents resulted in surface enrichment of carbon and tin compared to negative control (p ≤ 0.001); brushing removed parts of carbon and tin (p ≤ 0.001). Chitosan shows different properties under erosive and erosive/abrasive conditions. Under erosive conditions high viscosity might be helpful, whereas lower viscosity seems to be more effective in cases of chemo-mechanical challenges.

Head posture and dental wear evaluation of bruxist children with primary teeth.

UNLABELLED: The aim of the present study was to compare the head position and dental wear of bruxist and non-bruxist children with primary dentition. METHODS: All the subjects had complete primary dentition, dental and skeletal class I occlusion and were classified as bruxist or non-bruxist according to their anxiety level, bruxism described by their parents and signs of temporomandibular disorders. The dental wear was drawn in dental casts and processed in digital format. Physiotherapeutic evaluation and a cephalometric radiograph with natural head position were also performed for each child to evaluate the cranio-cervical position for the bruxist group (n = 33) and the control group (n = 20). The variables of the two groups were compared, using the Student t-test and Mann-Whitney U-test. RESULTS: A more anterior and downward head tilt was found in the bruxist group, with statistically significant differences compared with the controls. More significant dental wear was observed in the bruxist children. CONCLUSIONS: Bruxism seems to be related to altered natural head posture and more intense dental wear. Further studies are necessary to explore bruxism mechanisms.

Thickness measurement of worn molar cusps by ultrasound.

This study aimed to evaluate the effectiveness of an ultrasonic system for in vitro measurement of cusp tips of human teeth. Each worn cusp of 12 molar teeth was measured with an industrial ultrasonic system. The teeth were sectioned and measured by polarized light microscopy. The ultrasonic measurements and histological readings were moderately correlated (r = 0.601, p < 0.01). The ultrasonic system used in this study seemed a promising method for measuring thickness of worn cusp tips of extracted human molar teeth.

Accuracy of ultrasound measurement of progressive change in occlusal enamel thickness.

OBJECTIVE: To evaluate the effectiveness of ultrasound on measuring the thickness of enamel in abrasion. STUDY DESIGN: Flat areas on occlusal surfaces of 20 premolar teeth were marked. Two initial ultrasonic measurements on marked areas were obtained by the first researcher. Then the tooth was measured in the axial direction with a compass. The cusp tips were abraded by an abrasive paper, then the second and third ultrasonic measurements were taken. The second researcher repeated the third ultrasonic measurement to evaluate the interobserver variation. All specimens were sectioned and the remaining enamel thickness was measured under polarized light microscope. RESULTS: Pearson's correlation analysis showed a high level of intraobserver agreement for the ultrasonic measurements of the first researcher (r = .891, P < .000 initial; r = .690, P < .001 first abrasion; r = .885, P < .000 second abrasion). Third ultrasonic measurements of the first and second researchers were positively and significantly correlated with histological readings (r = .966, P < .000; r = .466, P = .039). CONCLUSIONS: The ultrasonic system used in this study was reliable in measuring enamel thickness.

The laboratory assessment of enamel erosion: a review.

OBJECTIVES: To review the various methods and techniques available to assess enamel erosion in vitro. DATA: Peer reviewed scientific articles. SOURCES: Medline and Web of Science searches and manual searching. STUDY SELECTION: Laboratory based assessments only included. CONCLUSIONS: A number of macroscopic and microscopic techniques have been used to assess enamel erosion in vitro and in situ. This review examines techniques which are either well established or comparatively novel techniques that are being explored for their potential.

Palaeopathological and variant conditions of the Homo heidelbergensis type specimen (Mauer, Germany).

Although early Homo specimens are now known from a number of African, Asian and European Middle Pleistocene sites, the taxon Homo heidelbergensis was initially introduced for the Mauer jaw recovered in 1907. Fossil hominids from the earlier Middle Pleistocene of Europe are very rare and the Mauer mandible is generally accepted as one of the most ancient, with an age of approximately 700 kyr. A new preparation of the mandible was conducted in 1996 and gave rise to the detailed palaeopathological examination which is presented here. Based on comparative analyses, the extreme breadth of the mandibular ramus and its flat intercondylar incision, in conjunction with the flattening and broadening of the coronoid process tip, results either from an idiosyncratic pattern of the course and insertion of the temporalis muscle on the coronoid process or from the temporalis possessing an accessory head. The incidence of periodontal pocketing, together with a vertical reduction of the alveolar margin to approximately 3.00 mm, and a slight protuberance formed in vicinity of the right M(2)can safely be interpreted as pathognomonic indications of periodontal disease. The short distance between the enamel-dentine junction of the teeth and the horizontal alveolar margins could either be an inherited variant or may result from incipient osteoporosis. In addition, an arthrotic condition with slight osteophytic peripheral exostoses and an arthrolit (i.e. an articular calculus or "joint mouse") on the left condylus articularisand a depression in the medial part of the left mandibular condyle extending into the inferior part of the ramus are present. These features are indicative of a trauma-induced osteochondrosis dissecans. The diagnosis therefore suggests that the observed depression results from a well-healed fracture. This traumatic event illustrates the demanding living conditions endured by humans during the European Middle Pleistocene. The variations and pathological conditions observed in Mauer do not question the mandible's role as type specimen for the taxon Homo heidelbergensis.

Tooth surface loss. 11. Surgical crown lengthening.

Restoration of worn teeth can be made easier by surgical crown lengthening. It improves appearance and facilitates tooth preparation. Anatomical features can limit the height that can be gained.

Recent findings in classification of osteogenesis imperfecta by means of existing dental symptoms.

The findings are based on a clinical investigation conducted on forty-nine patients suffering from osteogenesis imperfecta (OI), as well as on a questionnaire study in which 117 osteogenesis imperfecta-affected persons or their parents were involved. The survey established pathological tooth discolorations as well as tooth abrasions. Dentinogenesis imperfecta (DI) was more frequently found in primary teeth than in permanent teeth. There were no gender-specific differences. Radiological abnormalities were found in both, abraded and/or discolored teeth, as well as in clinically normal appearing teeth. In most cases there were club-shaped extensions of the pulp chambers and obliterations of the root canals. The probability that dentinogenesis imperfecta occurs as an accompanying symptom of osteogenesis imperfecta was not dependent on the degree of skeletal severity. The self-assignment according to A and B forms of osteogenesis imperfecta types I and IV in accordance with the presence/absence of dental symptoms was contradictory, since the literature was based on varying classifications.

Spatial resolution in radiometric analysis of enamel loss. A pilot study.

This pilot study was undertaken to determine whether spatial resolution affects radiometric analyses aimed at detecting progressive enamel loss. Four teeth were weighed, attached to a positioning device, and evaluated with radiography. A 1 mm strip of enamel was removed from each tooth, and the teeth were weighted again and reexamined by radiography. This process was repeated five times until 1/2 mm of dentin was removed. The radiographs were digitized twice with 59 and 200 microns pixels at 8 bits, providing two series of images with the optical densities converted into 256 gray levels. Each series of images was adjusted for contrast variation. Regions of interest were drawn on the crowns, and cumulative percent histograms (CPHs) were calculated. Within a series of CPHs enamel reduction resulted in shifts in the CPHs that were directly proportional to the amount of enamel removed. CPH shifts associated with the smaller 59 microns pixels accounted for 68% of the variation in weights caused by enamel reduction, whereas the shifts associated with the larger 200 microns pixels accounted for 50%. The results indicate that pixel size does affect radiometric determinations of enamel reduction.

Population variation in tooth, jaw, and root size: a radiographic study of two populations in a high-attrition environment.

Radiographs were taken of the jaws of skeletal remains of two populations of different-phenotype Prehistoric Australians from Roonka and Early New Zealanders (Maoris). On these radiographs crown, root, and corpus size were measured. Corpus height was subdivided into alveolar bone height, defined as the bone superior to the mandibular canal, and basal bone height, defined as that inferior to the mandibular canal. Both between and within the two populations there was a significant and negative correlation between crown size and corpus height. The differences between the two populations in corpus height were associated with differences in alveolar bone height rather than basal bone height and support hypotheses associating continued eruption of adult teeth with growth of the alveolar bone. The findings also support previous studies that have shown only a low correlation between crown size, root size, and corpus height.

[X-ray cephalometric characteristics of the facial skeleton in increased abrasiveness of the hard dental tissues]. / Rentgenotsefalometricheskaia kharakteristika litsevogo skeleta pri povyshennoi stiraemosti tverdykh tkanei zubov.

X-ray cephalometric analysis of 123 profile teleroentgenograms revealed substantial differences in the composition of facial skeleton in the patients with three forms of generalized increased abrasiveness of teeth.

Quantitative assessment of tooth wear, alveolar-crest height and continuing eruption in a Romano-British population.

Although measurements from cement-enamel junction (CEJ) to alveolar crest (AC) have been used in assessing changes in alveolar-crest height as age or chronic inflammatory periodontal disease (CIPD) progresses, there is evidence from ancient populations that the position of AC remains almost constant throughout life and continuing eruption to compensate for attrition may explain why CEJ-AC measurements increase with age. Measurements of occlusal attrition and relationship of CEJ to AC were made on the cheek teeth of 500 Romano-British skulls by direct measurement or by reference to the fixed line of the inferior alveolar canal (IAC) on radiographs. Direct measurements indicated that there were usually no statistical differences between the vertical amounts of tooth substance lost by attrition and the change in the distance CEJ-AC as age progressed. Measurements on radiographs showed that posterior teeth continued to erupt to compensate for attrition and the AC remained static as age progressed. Bone deposition at the AC was seen in the majority of ground sections. Thus tooth wear appears to be compensated by continuing movement of teeth in an occlusal direction. The position of the AC remained almost constant throughout life; AC bone lost by CIPD seemed to be replaced during continuing tooth eruption.