Intake of different alcoholic beverages and periodontal condition

Objective: The objective of this study is to study the association of alcoholic beverages and serum gamma-glutamyltransferase (GGT) level with periodontal condition.

Material and methods: The study included 4294 dentate, non-diabetic Finnish adults aged 30?65 years who underwent periodontal examination during the Health 2000 Survey. The number of teeth with deepened (≥4?mm) periodontal pockets was the outcome. The exposures were self-reported beverage-specific alcohol intake (amount and frequency) and serum GGT level. The relative risks (RRs) and 95% confidence intervals (CI) were obtained by fitting zero-inflated negative binomial regression models.

Results: We found no consistent association of either the intake of different alcoholic beverages or GGT level with the number of teeth with deepened periodontal pockets in the total study population or among the non-smokers. Among the highly educated non-smokers, spirit intake was associated with a low likelihood of having teeth with deepened periodontal pockets; RRs varied between 0.3 and 0.8. Among the non-smokers who had basic or intermediate education, spirit intake was associated with a higher likelihood of having teeth with deepened periodontal pockets; RRs varied between 1.2 and 1.8.

Conclusion: In general, neither the intake of different alcoholic beverages nor the GGT level was consistently associated with the number of teeth with deepened periodontal pockets.     

Protection hypothesis for composite wear.

Significant occlusal wear occurs on posterior composite restorations in areas without direct contact with opponent teeth (contact-free wear) in addition to wear at the contacts. Recent research has indicated that all occlusal posterior composite surfaces wear, and those surfaces show decreasing wear rates over time. This provides more evidence for an earlier theory proposed by J?rgensen et al. (1979) that composite contact-free wear is a function of access and attrition caused by small particles in the food bolus. This hypothesis is now called the "protection theory" or "protection hypothesis" for wear. Macroscopic protection or "sheltering" from wear is provided by cavity preparation walls. Microscopic protection against resin matrix wear is provided by filler particles that are close together. Clinical evidence supporting the protection hypothesis comes from recently confirmed low wear rates for microfill and hybrid composites. The objective of this work was to calculate the minimum inter-particle spacing required for microscopic protection (wear resistance) for composites based on assumptions of packing fractions (0.68) with small particles (0.02 microns radius) for dispersed versus agglomerated conditions. An inter-particle spacing (IPS) of < 0.10 microns was assumed to afford wear protection. The results are that only 1.5-6.0 volume percentage microfiller is theoretically required to generate an IPS of 0.1 micron for composite microscopic protection. However, microfiller particles are suspected to agglomerate into clusters. Modified calculations for that effect indicate that at least 35% filler is required to provide microscopic protection. This effect explains much of the 3 to 5 year clinical research results for microfills and hybrids.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro wear device for determining posterior composite wear.

BACKGROUND: An in vitro device has been developed to predict the long-term clinical performance of posterior composite resins. In contrast to most systems, it is based on three-bodied wear--the type of wear generated by food bolus during mastication. METHODS: The authors wear-tested two groups of materials that included posterior composite resins, a castable ceramic, an amalgam and an unsalinated composite resin. After the wear-testing device concluded 400,000 cycles, the authors evaluated replicas of restoration surfaces for material loss. They used scanning electron microscopy to determine the mechanism of wear. RESULTS: The authors detected considerable differences in wear among the various materials included in the study. All of the differences, however, fell within the range of results obtained from the positive and negative controls (unsilanated composite resin and ceramic, respectively). A comparison of the in vitro wear values with the wear values obtained from a series of ongoing clinical studies at the same institution revealed a high level of agreement. Furthermore, replicas of the laboratory-tested composite resin samples revealed the same wear patterns as those generated from clinical restorations. The variation coefficients for the in vitro data generally did not exceed 5 percent, whereas those for the clinical data commonly averaged 20 percent. CONCLUSIONS: Based on the results of this study, the authors conclude that the in vitro testing device is reliably capable of predicting long-term clinical wear values. The results obtained after 92 hours of wear testing correlated closely with those obtained after three years of clinical testing. CLINICAL IMPLICATIONS: Long-term clinical studies are both time-consuming and expensive. Reliable in vitro wear-testing techniques allow manufacturers to develop or modify composite resin systems in considerably shorter periods.     

饮料对牙釉质表面显微硬度影响的研究

目的：研究不同饮料对牙釉质表面显微硬度的影响。方法：用不同种类饮料处理牙釉质后,采用维氏显微硬度仪测定牙釉质的处理前和处理后的1－7d表面显微硬度的改变。结果：饮料能引起牙釉质表面显微硬度的降低,降低的程度与饮料的种类有关,不同种类饮料导致牙釉质表面显微硬度降低的强度不同,差异有统计学意义（P＜0.001）。随时间的延长,表面显微硬度也随之降低（P＜0.001）。结论：饮料对牙釉质都具有脱矿作用,脱矿随饮料接触牙齿时间的延长而增加。     

Three-year occlusal wear of posterior composite restorations.

The specific aims of this study were to: 1) measure the occlusal wear of four different dental composite materials placed in the posterior teeth of adults; and 2) evaluate the effect of the clinical parameters, cavity class and tooth type on occlusal wear. Four different visible light-cured composite materials were used to make the restorations in this study. The restorations placed for this randomized clinical trial were scored through the use of an indirect evaluation system (M-L scale). The total sample size per recall ranged from 90 to 142 restorations from baseline to 36 months. The mean wear at 36 months for Heliomolar, J&J Experimental (Adaptic II) and P-30 was 45-54 microns, which is rather low compared to the recently reported wear of other composite materials. Marathon exhibited significantly greater wear with a mean of 174 microns at 36 months. The data also showed that cavity class and tooth type had no significant effect on the occlusal wear of the restorations made with the three low wear-rate materials, while restorations composed of the high wear-rate material exhibited more wear in molars than premolars; this effect was again not statistically significant. These data support the hypothesis that the overall wear of a composite restoration is more dependent on the material's properties than clinical parameters such as cavity class and tooth type.     

In vivo wear test for posterior composites. 1. Development of wear test predicting composite wear in vivo

A wear test method based on a new concept was developed for predicting the wear rate of posterior composite restorations in vivo. The concept based on the conclusions derived from our clinical tests on posterior composites that composite restorations would be deteriorated chemically and by repeated compressive stress as well as by abrasion by food passing during mastication. New wear tests were performed on several posterior restorative materials under various conditions to compare the effect of abrasion using the tooth-brush. The results of wear rate using the present test on specimens stored in a 0.1 N-NaOH solution (37 degrees C) for 6 days were parallel to those measured in clinical tests. However, the abrasion test results obtained using a tooth-brush on deteriorated specimens did not match the clinical data. These findings suggested that degradation or aging of specimens and repeated compressive stress are necessary for the wear test to simulate the wear of posterior composites in vivo.     

Effect of contact area size on enamel and composite wear.

The effect of contact area dimensions on the wear of composite specimens and their opposing enamel cusps was evaluated in vitro. Thirty-six standardized cylindrical composite specimens were placed into metal cavities (8 mm x 2 mm) and divided randomly into five groups. The composite used was a fine-particle hybrid and was stressed as follows: storage in 75% aqueous ethanol solution for 24 h, toothbrush/toothpaste-abrasion for 30 min, followed by 300 thermal cycles in water ranging from 5 degrees to 55 degrees C and simultaneous 120,000 occlusal chewing loads at a frequency of 1.7 Hz at 53 N maximum force. In group 1 (n = 12), the occlusal chewing loads were applied by palatal cusps of extracted human maxillary molars with natural morphology. In groups 2 to 5 (n = 6), the cusp tips had standardized contact area dimensions of 0.26, 0.38, 1.18, and 4.10 mm2, respectively. Wear of composite specimens and antagonistic enamel cusps (means +/- SD) was assessed in microns by means of a 3-D scanner. Additionally, the contact surfaces of the restorations and of the antagonistic enamel cusps were evaluated by SEM. Increases in enamel contact areas after being loaded were measured by means of a digitizer and expressed in percent of the initial size before stress exposure. The wear of the composite specimens varied from 69.8 +/- 19.9 to 9.5 +/- 3.6 microns, and that of antagonistic enamel cusps from 31.3 +/- 3.4 to 8.8 +/- 1.5 microns. The increase in contact area varied between 27.8 and 0.1%.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of beverages on plaque acidogenicity after a sugary challenge

BackgroundCaries prevention traditionally has emphasized the restriction of cariogenic foods and beverages, but it has placed less emphasis on how the choice, combination and sequence of consumed foods and beverages may help reduce plaque acidogenicity. The authors conducted a study to examine whether whole milk, 100 percent apple juice or tap water affect dental plaque acidity in people after a sugary challenge.MethodsTwenty adults participated in a randomized controlled crossover study. Participants consumed four combinations of foods: 20 grams of dry sugary Froot Loops (FL) (Kellogg's, Battle Creek, Mich.) cereal, 20 g of FL followed by 50 milliliters of milk (FL/milk), 20 g of FL followed by 50 mL of juice (FL/juice) and 20 g of FL followed by 50 mL of water (FL/water). The authors used a touch microelectrode to take plaque pH readings at the interproximal space just below the contact area between the maxillary premolars on both left and right sides at two and five minutes after FL consumption and at two to 30 minutes after milk, juice or water consumption.ResultsConsumption of FL plaque pH (standard deviation [SD]) was 5.83 (0.68) at 30 minutes, whereas plaque pH (SD) in the FL/milk group was 6.48 (0.30), which was significantly higher than that for FL/juice (5.83 [0.49]) or FL/water (6.02 [0.41]) (P < .005) at 35 minutes.ConclusionDrinking milk after a sugary cereal challenge significantly reduced plaque pH drop due to the sugary challenge.Practical ImplicationsWhen discussing the cariogenicity of foods and beverages with patients, dentists and other health care professionals should emphasize that the order of ingesting sugary and nonsugary foods is important and may affect their oral health.     

In vivo occlusal wear of posterior composite restorations.

The available and proposed methods for determining the in vivo occlusal wear values of classes 1 and 2 restorations made of resinfilled composite materials are critically reviewed. A methodology to be used to address the fundamental question of the link between the wear of the in vivo restorations and the relevant mechanical properties of the materials is outlined. For the four commercial formulations of composite materials which are currently "fully acceptable" to the American Dental Association (Estilux Posterior, Ful-Fil, Occlusin, and P-10), analysis of the published clinical wear values versus time data is performed.     

不同饮料对乳牙釉质酸蚀作用初探

目的:使用激光荧光法测定市售饮料对乳牙釉质表面的酸蚀作用。方法:48个离体乳前牙随机分为4组,分别浸泡于可乐、鲜橙汁、优酸乳和去离子水中25 h,每5 h换液1次。通过扫描电镜进行釉质表面形态学观察,并使用激光荧光诊断仪进行定量分析。结果:可乐组和橙汁组样本酸蚀脱矿明显,实验前后激光荧光值差异有统计学意义(P<0.05),可乐酸蚀脱矿能力显著高于橙汁。优酸乳组脱矿不明显,且电镜下可见钙化物沉积。结论:软饮料可造成乳牙釉质酸蚀脱矿,应当控制儿童软饮料的消耗并建议改变饮用方式。     

The effects of enamel wear on the metal-porcelain interface

This study evaluated the effects of wear of human tooth enamel on the metal-porcelain interface. Failure in the porcelain half of the specimens occurred only in specimens where the metal angle was 60 degrees. There was failure in one of four of the noble metal alloy specimens. With the base metal alloy specimens, in the first group two specimens showed cracks in the preparation stage while the other two showed no sign of cracks either before or after testing. In a second group of four base metal alloy specimens with a 60-degree angle, all four specimens showed cracks in the porcelain after glazing. These specimens were repaired by grinding out the cracks and filling them with porcelain. After wear-testing, all four specimens developed cracks. The data indicate that the acute angle of metal (60 degrees) at the metal-porcelain interface was more conducive to crack formation than were the other two angles tested. Therefore, in the case of a metal-ceramic restoration, with the occlusion on the metal, an acute angle of metal would not be appropriate. Furthermore, under clinical circumstances cracks that occur after glazing, as arose with the last four base metal alloy specimens (60 degrees), probably should not be ground out and refilled with porcelain. The results of this study indicate that such a practice in a clinical situation could lead to eventual fracture of the porcelain. The porcelain half of the specimens had a deeper and wider wear track than its metal counterpart, which indicated that the porcelain is less resistant than the metal to wear by enamel.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship between abrasive wear and microstructure of composite resins.

The in vitro abrasion resistance of seven commercial composite resin restorative materials has been measured. Analysis of the composite microstructures shows that abrasion rates are dependent upon the size, hardness, and volume fraction of particles in the material. The most abrasion-resistant composites contain a high volume fraction of large, hard particles.     

Effects of cyclic loading on occlusal contact area wear of composite restoratives.

OBJECTIVES: To investigate the effects of cyclic loading on occlusal contact area (OCA) wear and the possible presence of fatigue wear mechanisms in four composite resins (Silux, Z100, Ariston and Surefil) using a reciprocal compression-sliding test apparatus. METHODS: Six specimens were made for each composite material and the amalgam alloy (Dispersalloy) control. The wear specimens were subjected to wear testing at 20 MPa with artificial saliva as lubricant. Wear depth (microm) was measured using profilometry every 20,000 cycles up to 120,000 cycles. The worn specimens were subjected to SEM to determine the presence of fatigue wear mechanisms. Results were analyzed using ANOVA/Scheffe's test (P<0.05) and Pearson's Correlation (P<0.01). RESULTS: Dispersalloy had the lowest wear at all cyclic intervals. For all materials, OCA wear increased with increased number of cycles. Although Dispersalloy, Ariston and Surefil experienced no significant increase in wear between each 20,000 cycles increment, a significant increase was observed with Silux. For Z100, a significant difference was observed only from 40,000 cycles onwards. Both Z100 and Dispersalloy exhibited fatigue wear after wear testing for 120,000 cycles. Cyclic loading resulted in deep and wide microcracks in Silux. Fatigue wear was not observed with Silux, Ariston and Surefil. SIGNIFICANCE: The effects of cyclic loading on wear is material dependent. While some restorative materials exhibit fatigue wear, others exhibit deep microcrack formation with extended cyclic loading. The latter may precipitate catastrophic failure despite the low wear observed. Care should, therefore, be exercised when selecting materials for posterior stress-bearing areas.     

Water and abrasive effects on three-body wear of composites.

The degrees of in vitro three-body wear resistance of a hybrid, a small-particle, and a microfilled composite were determined after water storage for up to 24 months. The hybrid composite was the most wear-resistant, while the microfilled composite showed the most wear. The hybrid composite showed no loss of wear resistance as a result of water storage. The small-particle composite showed a decrease in wear resistance after water storage only when tested with silicon carbide abrasive. The wear resistance of the microfilled composite decreased following water storage when tested with either a soft (CaCO3) or a hard (SiC) abrasive. For all composites, the soft abrasive was not capable of causing preferential wear of the polymer matrix, as observed on in vivo specimens. Instead, the filler particles became flattened, with minimal loss of interparticle substance. The hard abrasive did cause preferential wear of the matrix. All composites absorbed water and leached silicon during water storage, indicating that the filler-polymer bond was attacked by hydrolytic degradation. Scanning electron microscopic evaluation of the three-body wear specimens indicated that the in vitro wear method did not duplicate in vivo wear conditions (e.g., the hard abrasive caused excessive wear and chipping of the filler particles in vitro, a pattern that was not usually observed in vivo). Filler-polymer de-bonding was observed on in vivo specimens of all the composites, while it was found only on the in vitro microfilled composite specimens. These findings suggest that filler dislodging is a complex process that cannot be simulated with the in vitro wear method used in this study, not even after prolonged water storage.     

Erosive effects of common beverages on extracted premolar teeth

BACKGROUND: Dental erosion is highly prevalent today, and acidic drinks are thought to be an important cause. The aim of the present investigation was to determine the erosive potential of a range of common beverages on extracted human teeth. METHODS: The beverages were tested for their individual pHs using a pH meter. The clinical effects of the most erosive beverages were determined by the degree of etching and Vickers microhardness of enamel. RESULTS: The results showed that many common beverages have pHs sufficiently low to cause enamel erosion. Lime juice concentrate (pH 2.1) had the lowest pH, followed by Coca-cola and Pepsi (both with pH 2.3) and Lucozade (pH 2.5). The erosive potential of these beverages was demonstrated by the deep etching of the enamel after five minutes. The Vickers Hardness of enamel was reduced by about 50 per cent in the case of lime juice (p < 0.001) and 24 per cent in the case of Coca-cola (p < 0.004). Addition of saliva to 50 per cent (v/v) of Coca-cola completely reversed the erosive effects on the enamel. CONCLUSIONS: Although only a few of the beverages with the lowest pHs were tested, the present study showed that the most acidic drinks had the greatest erosive effects on enamel. While saliva was protective against erosion, relatively large volumes were required to neutralize the acidity.     

Effects of occlusal and brushing cycles on wear of composite resins in combined wear test

The effects of occlusal cycles and brushing cycles on wear of composite resins were investigated using a combined wear test, which carried out occlusal and toothbrush wear tests alternately. Worn volume and maximum worn depth were measured to evaluate wear under four combinations of two different cycles (occlusal cycles: 50 and 150 cycles; brushing cycles: 20 and 50 cycles). With composite resin APX, which consisted of relatively large and irregular-shaped filler particles, its worn volume and worn depth significantly increased with the number of occlusal cycles. With composite resin Z100, which consisted of relatively small and irregular-shaped filler particles, its wear values significantly increased with both brushing and occlusal cycles. With composite resin SRE, which consisted of small, irregular-shaped, inorganic filler particles and large organic filler particles, its worn volume significantly increased with the occlusal cycle when under a lower brushing cycle. With composite resin SDX, which consisted of spherical inorganic filler particles and large organic filler particles, its wear was not influenced by increases in both brushing and occlusal cycles.     

Effects of gamma radiation on the in vitro wear of composite restorative materials.

The effects of gamma radiation at therapeutic dosage levels on the wear of three anterior (two light-cured and one autocured) composites and a light-cured posterior composite were studied in vitro. Specimens were subjected to successive sets of 100 abrades to a maximum of 500 abrades on a reciprocating arm abrader, with the dimensional change being recorded between the sets of abrades. The data showed that there were no significant effects on the wear rates of any of the materials tested. The rate of height loss was similar for the two hybrid composites tested (P less than 0.05), as was that for the microfilled and conventional material (P less than 0.05). There was, however, a significant difference (P greater than 0.001) in the wear behaviour between the two groups.