irradiation demonstrated no visible cracks but a 20% reduction in dentin bending strength.
Clinical Significance.—Using the dry laser significantly damaged the dentin surface and diminished the bending strength of the dentin. Using a wet approach the damage was less, with only a 20% decline in dentin bending strength. The presence of cracks created by the lasers reduces the tooth’s fracture resistance and compromises restorations. We need to weigh the advantages and disadvantages of each method to choose the best option.
Staninec M, Meshkin N, Manesh SK, et al: Weakening of dentin from cracks resulting from laser irradiation. Dental Materials 25:520-525, 2009 Reprints available from M Staninec, Dept of Preventive and Restorative Dental Sciences, Univ of California, San Francisco, CA 94143; email:
[email protected]
Nutrition Methodological issues in oral health/diet linkage Background.—With the increasing number of older adults and an associated increase in edentulousness, interest has grown into whether altered oral and systemic health status is related to nutrition. Studies to date have not used consistent approaches to assessing diet and nutritional status. Standards for the basic nutritional study methods were defined by a consensus workshop at McGill University Montreal in 2005. Their recommendations were reviewed to determine the impact of oral health on nutrition and identify future directions for research.
foods/nutrients by groups or, if repeated, means and distributions for groups. FFQs are useful for assessing patterns of habitual intake and can be focused on the intake of specific dietary components. Advantages include self-administration and distribution by mail. They are most appropriate for estimating food types and frequencies so comparisons can be made between groups or bands of consumption. Dietary histories taken in person require a significant commitment of personnel and time. They are more appropriate for clinical dietetic practice than research.
Methods.—The consensus workshop considered data relevant to nutrition and dental status from studies published between 1980 and 2005 in English, including original articles in which a range of nutritional methodologies were applied to the study of oral health impact. The methods reviewed were (1) dietary intake, (2) anthropometric measures and body composition, (3) biochemical indexes of dietary intake and nutritional status and functional markers, and (4) chewing ability.
Prospective approaches document current food intake and include precise weighing, weighed food diaries, and estimated food diaries. Precise weighing requires complete subject cooperation and can alter normal dietary consumption. It is unsuitable in studying compromised oral function and nutrition. The weighed food intake diary involves the subject weighing and recording all foods and drinks consumed or left over, noting time of consumption over a specific period, usually 7 days. Food weight is then translated into nutrient consumption. Subjects may alter food intake because it is hard to record or too fatiguing. The Portable Electronic Tape Recorded Automatic (PETRA) scales record a verbal description of the food and may overcome literacy limitations. This method may be too exacting for obtaining some types of dietary information but can be used in all types of studies requiring dietary information. Estimated food diaries followed by an interview burden the researcher more and may not alter normal eating patterns.
Dietary Intake.—In measuring dietary intake, it is important to recognize that food choice alterations reflect more on personal choice, food enjoyment, and satisfaction with eating than on nutritional adequacy. Although quality of life may suffer, there may be no dietary deficiencies. Dietary intake can be assessed retrospectively or prospectively. Retrospective analysis methods document past diet and include 24-hour dietary recalls, food frequency questionnaires (FFQs), and dietary histories. The 24-hour recalls, although less expensive and easier on the subject, provide unreliable data for individual dietary assessment but may be appropriate for measuring mean intake of
262
Dental Abstracts
Food composition tables translate foods into nutrients. They offer the best estimates of nutrient content per 100 g of food and are often integrated into research-appropriate
software. Some subjectivity is introduced when these tables do not contain an exact match for a food. Dietary intake is also measured against standard goals or dietary recommendations. Physical activity level (PAL) must also be considered. Protein intake can be compared to nitrogen excretion to validate recorded dietary data. Measuring Body Components.—Anthropometric measures of body composition also help assess nutritional status. Body weight and height can determine body mass index (BMI), which is related through defined values with obesity, overweight, underweight, and normal weight. BMI data are limited in elderly subjects who have agerelated height loss. Measurements of triceps thickness (TSF) or skinfold thickness at several sites can help estimate percentage of body fat present. Waist circumference indicates subcutaneous and intra-abdominal fat stores, which are related to cardiovascular disease risk. More sophisticated and expensive methods are also available. For some elderly populations it is appropriate to measure muscle mass after dental prosthetic rehabilitation and/or dietary intervention. Mid arm circumference (MAC) provides an estimate of lean body mass and can be combined with TSF to determine mid upper arm muscle circumference (MAMC). The accuracy and precision of these measurements must be controlled, with serial measures obtained by the same trained observer. Comparisons between current and baseline values should also be done. Biochemical Indexes and Functional Markers.—Nutritional status can be revealed by measuring concentrations of nutrients in biological samples such as blood, urine, saliva, hair, and nails. These objective results are then compared to recent dietary intake, long-term intake, or body stores. Included among the biochemical indexes are the antioxidant vitamins A, C, E, and carotenoids; B vitamins; vitamin D; dietary minerals; and proteins. These may also serve as functional markers; homocysteine is a biomarker for vitamin B and cardiovascular disease risk, dietary antioxidants are functional markers for oxidative damage, and lignans are biomarkers for whole-grain consumption and fiber status. Chewing Ability.—Chewing function can also be measured. Basic methods include chewing a known weight of
a test food for a set number of chewing motions and determining particle size or noting the number of chewing strokes needed to reduce a certain quantity of food to a bolus that can be swallowed. More sophisticated methods include electromyography to measure chewing force. The number of teeth present, the number of posterior opposing pairs of teeth, or occlusal indexes can serve as proxy methods indicating chewing ability. Perceived chewing ability is measured as well, but further research is needed to make this value useful.
Clinical Significance.—Obviously the study of relationships between nutrition and altered oral status is complex. Several recommendations seem appropriate. First, include a dietician or nutritionist skilled in nutrition analysis in the study design; second, use an appropriate and robust data collection method with objective validation measures; third, include an objective dietary measure such as a specific biomarker in studies of diet and/or changes in diet; fourth, continue your observations for more than 3 days for food groups and macronutrients and longer for micronutrients; and fifth, include evidence on eating difficulties and food avoidance to detail the impact of dental function on eating-related quality of life, but do not make these the only data obtained. Other aspects to include in these studies are perceived chewing function (specific to studies of dental function and nutrition), anthropometic measurements (with attention to age-related effects), and specific biomarkers. To really understand the link between oral health and diet and nutritional status will require further careful research with these recommendations in mind.
Moynihan P, Thomason M, Walls A, et al: Researching the impact of oral health on diet and nutritional status: Methodological issues. J Dent 37:237-249, 2009 Reprints available from P Moynihan, School of Dental Sciences, WHO Collaborating Ctr for Nutrition and Oral Health, Newcastle Univ, Framlington Pl, Newcastle upon Tyne NE2 4BW, United Kingdom; e-mail:
[email protected]
Occlusion Occlusal and space changes with age Background.—The natural changes that occur in arch dimensions, spacing, and other occlusal parameters through late adolescence and early adulthood influence the stability
of orthodontic treatment results, guide retention procedures, and form a baseline for assessing relapse after orthodontic intervention. The development of discrete occlusal
Volume 54
Issue 5
2009
263