Arch Oral Biol Research Articles

The effects of continuous axially-directed intrusive loads on the erupting rabbit mandibular incisor

A cantilever beam strain-gauge transducer was used to apply continuous light intrusive loads (0.2–0.4 and 2.5 g) to unimpeded mandibular incisors. Tooth position was continuously monitored using a variable capacitance displacement transducer. After 4 days of unimpeded eruption, the animals were divided into three experimental groups: no axial loading (6 rabbits); 0.2–0.4 g of axial loading (3 rabbits); 2.5 g of axial loading (3 rabbits). During a 4-h period, light forces (0.2–0.4 g) slowed eruption to a stop, whereas a heavier force (2.5g) intruded the teeth. The data support Burn-Murdoch's (1981) ( Archs oral Biol. 26, 939–943) contention that the eruptive force of unimpeded continuously-erupting incisors is significantly less than previously thought.

Salivary pH-rise activities in caries-free and caries-active naval recruits

Kleinberg (1967) ( Archs oral Biol. 12, 1457–1473) has observed that the incubation of a salivary sediment/supernatant mixture with a low concentration of glucose produces a pH drop followed by a pH rise. As this pH-rise effect could elevate oral pH in vivo, the degree of such activity could be directly related to caries resistance. The pH-rise of paraffin-stimulated whole saliva samples from 54 caries-free and 54 caries-active male naval recruits was compared in two assays. The first, conducted with sediment/supernatant/2.8 mM glucose mixtures, showed no significant differences for mean pH versus time profiles for 26 caries-free and 26 caries-active subjects. Concomitant assays, in which 3.33 mM arginine and water replaced the supernatants in the assay mixtures, showed slightly higher mean pH/time profiles, with higher minima for the caries-free subjects. These profile differences were statistically significant for the arginine-cortaining mixtures, a result attributed to different microbial distributions for the caries-free and caries-active sediments. The second assays were conducted on saliva supernatants from 28 caries-free and 28 caries-active subjects, employing a strain of Lactobacillus casei in place of salivary sediment in the assay system. No statistically significant differences were evident between the mean pH/time profiles for the two groups of subjects, although a significant positive correlation was observed between pH minimum and bicarbonate content of the samples Thus no relationship of salivary pH-rise activity and caries experience was found.

Developmental communalities in tooth emergence timing.

Intercorrelations and communalities are now well known for tooth formation (Garn et al., J Dent Res 39:1049, 1960), crown size of the permanent teeth (Moorees and Reed, Arch Oral Biol 9:685, 1964; Garn et al., J Dent Res 44:350, 1965), the deciduous teeth (Garn et al., JDentRes 56:1214, 1977), and crown size of deciduous teeth during odontogenesis (Garn et al., J Dent Res 58:554, 1979). However, comparable analytic information has not been presented for postnatal tooth emergence timing of 11 through M2. To explore these emergence relationships and their relative magnitudes, tooth emergence (timing) correlations were calculated using coded emergence data derived from serial casts of 204 participants in the Longitudinal Study of the University of Michigan (Moyers et aL, Standards of Human Occlusal Development, Ann Arbor: The Center for Human Growth and Development, 1976). Individual ages of tooth emergence were Z-scored for males and females separately for each of 28 permanent teeth, and the entire matrix of 121 pooled-sex tooth-pair intercorrelations was then computer correlated. Correlation coefficients for intra-quadrant pairs, antimeres, isomeres, and teeth separated by numbers of intervening teeth were separately averaged using the z transform of r As snown in the Table, where correlations are

Letters to the Editor

There is presently some difficulty with fluoride supplementation for a child in the first year of life. The American Academy of Pediatrics regimen for supplemental fluorides produced mild fluorosis in some subjects (Aasenden R, Peebles IC: Arch Oral Biol 19:321-326, 1974), and infant formulas may presently have variable amounts of fluorides. See Table in the PDF File This regimen is needed only in areas that do not have optimally fluoridated water, and when infants are ingesting commercial infant formula, no supplementation may be necessary.

Maternal and gestational influences on deciduous and permanent tooth size.

Although there have been suggestions that prenatal factors could affect crown dimensions (Bailit and Sung, Archs Oral Biol 13:155-166, 1968; Cohen, Baum, Garn, Osario and Nagy, in: Orofacial Growth and Development, Dahlberg and Graber, eds., Mouton Publishers, The Hague, 1977, pp 119-126), limitations of sample size and investigative design restrict conclusions on the magnitude of the influences. However, using newly-acquired odontometric data on selected participants in the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke (NCPP), it is now possible to show systematic effects of three maternal and six developmental conditions on mesiodistal and buccolingual dimensions of both deciduous and permanent teeth. The basic sample consists of 870 white participants studied at the time of their seven-eightyear psychological examinations in 1972 and 1973. They were selected from six cooperating institutions from the Atlantic seaboard and the West Coast (Niswander and Gordon, The Women and Their Pregnancies, D.H.E.W., Washington, 1972). Diabetes, hypothyroidism, and hypertension were the three maternal conditions selected for exploration. Gestation length, birth weight, and birth length were among the fetal or developmental variables studied. The odontometric analyses primarily involved the permanent incisors, first molars and deciduous cheek teeth (dc through dm2). A group of clinically normal children was also included for comparison, since single-source odontometric standards for deciduous and permanent teeth did not exist at the time the project was conceived. Mean crown dimensions of the normal NCPP group proved to be virtually indistin-

Diffusion through bovine tooth enamel as related to the water structure in its pores

Diffusion coefficients of 86Rb +, 36Cl −, [ 3H]-sorbitol and [ 14C]-glycerol through enamel were determined both in the absence and the presence of urea or t-butanol which are known for their structure-breaking and structure-promoting properties respectively in aqueous solutions. Their effect on the diffusion coefficients could be explained solely on the basis of the respective shifts in the relative viscosities of the aqueous solutions, indicating that the water of the transport phase is probably free water, in accord with explanation for the extra increase of diffusion coefficients with temperature (Burke and Moreno, Archs oral Biol. 17, 433–437 (1975)) by the hypothesis that the amount of free water increases with temperature at the expense of bound water.

Orthodontic Treatment and Periodontal Status

Histologic Evidence for Impaired Growth Control in Diphenylhydantoin Gingival Overgrowth in Man Hassel, T. M., Page, R. C. and Lindhe, J. Arch Oral Biol 23: 381, May, 1978. To investigate the cellular and extracellular composition of the diphenylhydantoin (DPH) induced overgrowth, 12 epileptic patients medicated with DPH and who manifested gingival enlargement of the fibrous type, were studied. A control group of age-matched nonepilep- tics with healthy gingiva and no exposure to DPH were studied. Sections of excised interdental papillae were stained and fibroblast nuclei present within a given mass, were counted. When analyzed by direct count, neither nuclear length nor number of nuclei per unit area of DPH enlarged gingival tissue differed from normal gingiva. The conclusions drawn were that there is no evidence of hypertrophy, hyperplasia, nor fibrosis but rather a gingival overgrowth of normal compositon. Departments of Pathology and Periodontics, and the Center for Research in Oral Biology, University of Washington, Schools of Medicine and Dentistry, Seattle, Wash 98195. Dr. Gary Galovic Retention and Plaque-Inhibiting Effect in Man of Chlorhexidine After Multiple Mouth Rinses and Retention and Release of Chlorhexidine After Toothbrushing With A Chlorhexidine Gel Bonesvoll, P. Arch Oral Biol 23: 295, No. 4, 1978. To study the retention of Chlorhexidine after multiple mouth rinses of varying concentrations and to relate the findings to the plaque- inhibiting effect of Chlorhexidine measured on short-term sucrose- stimulated plaque, Chlorhexidine retention was measured during 10 consecutive 15-second mouth rinses with 10 ml of 0.05, 0.10, 0.20%; and 20 ml of 0.05% chlorhexidine-digluconate. Retention of the drug in the mouth was increased by multiple mouth rinses and by increasing the rinsing volume or concentration. In the plaque-inhibition experiment, rinsing with 10 ml of a 15% sucrose solution every 2 hours increased the plaque. Retention after toothbrushing with a 1.0% chlor- hexidine-digluconate gel was the same as the retention after a 0.1% rinse. The release of Chlorhexidine into saliva during the following 24 hours followed the same pattern as observed earlier after Chlorhexidine mouth rinses. Retention varied greatly between subjects. Department of Physiology and Biochemistry, Dental Faculty, University of Oslo, Oslo, Norway. Dr. Yau-Fwu Huang A Complication of Orthodontic Therapy: Localized Facial Recession and Loss of Attached Gingiva Treated by Grafting Israel, H. Angle Orthod 48: 149, April, 1978. Frequently problems which in reality were mucogingival defects of missing attached gingiva, were formerly treated as frenai aberrations by frenectomy. Three cases were described to illustrate orthodontic patients with areas of loss of attached gingiva, gingival recession (gingival cleft), and muscle pull of the free gingival margin. The three patients were treated with free gingival grafts to create new attached gingiva. The purpose of the article was to help orthodontists become aware of the nature of the problems and current means of treatment. The goal of treatment suggested was to approximate tissue attachment as close as possible to the cementoenamel junction for aesthetics. Children's Medical Center, 1735 Chapel Street, Dayton, Ohio 45404. Dr. Larry Johnson

Lower lip displacement during in-vivo stimulation of human labial muscles

Displacement was measured at the lower lip midline and the corner of the mouth during direct electrical stimulation of labial muscles. Trains of electrical stimuli were delivered through hooked-wire electrodes to produce tetanic contractions in depressor labii inferior, mentalis, orbicularis oris inferior and depressor anguli oris. Stimulation of mentalis moved the lip superiorly and anteriorly, and depressor labii inferior stimulation produced movement in the opposite direction. When stimulated at a lateral electrode placement, orbicularis oris inferior moved the midline of the lip superiorly and posteriorly. Stimulation of orbicularis oris inferior at the midline produced wrinkling of the skin in and around the vermilion of the lip. The major influence of depressor anguli oris stimulation was a large inferior movement at the corner of the mouth. The movements measured during stimulation were very similar to those observed previously during electromyographic activity of mentalis and depressor labii inferior ( Archs oral Biol. 23, 189–194).

Dimensional Communalities of the Deciduous Teeth

Although there have been numerous studies of the extent to which the crown dimensions of the permanent teeth are correlated (MOORREES and REED, Arch Oral Biol 9:685, 1964; GARN, LEWIS and KEREWSKY, J Dent Res 44:350, 1965) comparable information on deciduous tooth dimensional communalities is meagre. Moreover, it is not known whether the crown dimensions of the deciduous teeth show different patterns of correspondence from those exhibited by the permanent teeth of the same individuals. Turning, then, to optical-scanner (OPTOCOM) mesiodistal crown measurements of 204 boys and girls from Southeastern Michigan (VAN DER LINDEN et al, J Dent Res 51: 1100, 1972; GARN et al, J Dent Res 56:697, 1977) complete intercorrelation matrices were calculated for 20 deciduous teeth, for boys and girls respectively, and compared with correlations for 20 successional (permanent) teeth from the same individuals. Since correlations involving the right and left sides were not systematically different, the sides were pooled to simplify the presentation. However, crown-size correlations for boys and girls were analyzed separately, since a systematic sex difference emerged. Moreover, attention was given to individual teeth, to morphological classes, and to between teeth within each arch, in order to test for a distance effect. As shown in the table, deciduous tooth intercorrelations are slightly higher for boys in the sample (R = 0.54) than for girls (R = 0.45), a trend significant by sign test for 20 paired correlations (X2 = 7.2). Within the arches, the highest correlations are for teeth of the same morphological class (r = 0.64), then those for adjacent teeth (r = 0.56) and then for teeth more widely separated. Mean values for r are 0.43, 0.45 and 0.46 for 1, 2 and 3 intervening teeth, respectively. Finally, the mean value of r for 20 deciduous teeth is slightly higher than the mean mesiodistal crown-

Correlates of permanent tooth development in prenatal time.

Although calcification of the permanent teeth is not radiologically discernible until the first month after birth (GARN, LEWIs, and POLACHECK, J Dent Res 38: 135, 1959) developmental stages of I1, 12, Ml, and often C may be demonstrated in histological sections of jaws well before the 39to 41-week age horizon. It is of interest, therefore, to determine whether intra-uterine development of these permanent teeth is simply and linearly related to the conventional measures of fetal size, namely, crown-rump length (CRL) and weight. It is also interesting to ascertain whether the correlation between fetal size and the overall measure of permanent tooth development obtained by summing individual tooth stages is sufficient to make dental development a reference parameter in prenatal stu(dies. To do this, we have related the stage of development of Il, 12, and Ml in the maxilla and mandible separately to (1) crown-rump length, (2) weight, and (3) the base-10 logarithm of body weight in 34 grossly and histologically normal humani fetuscs. We have uised a simple system of staging as previously described by us (GARN and BURDI, J Dent Res 50: 1407, 1971; BURDI, GARN, and BABLER, Arch Oral Biol 19: in press, 1974). Data on permanent canines were excluded because the small number of fetuses providing definitive developmental information was insufficient to compute valid correlations involving C. Linearity of relationship,

Effect of cooking vessel composition on fluoride.

Cooked foods that are prepared in water containing fluoride are a source of dietary fluoride (OSIS ET AL, J Dent Res 52 (Special Issue): Abstract No. 239, 1973) . The evaporation that occurs with boiling is a potential source of more concentrated fluoride solutions. The material that the cooking vessel is made from also may have an effect on the fluoride content of water used in food preparation. Several metals form insoluble compounds with fluoride. Pyrex glass may absorb fluoride on its surface. Newer coatings applied to ease cleansing such as Teflon are chemically less reactive and could alter the effect of the structural material. To evaluate the effect of container composition on the fluoride available for incorporation into cooked foods, water was boiled in typical cooking vessels and the changes in fluoride concentration were measured. Tap water in a community whose water supply had been studied previously for fluoride content (FULI and PARKINS, J Dent Res 51: 666, 1972) was used. One-quart sauce pans that had received moderate prior use were selected. Four vessels of different composition (aluminum, stainless steel, Pyrex, and Teflon) were heated on a heavy duty hot plate. A quantity of one pint of tap water was analyzed for fluoride and placed in each vessel. The highest temperature setting on the hot plate control was used to bring the water to a vigorous boil. The heat then was reduced to maintain a moderate degree of boiling for 15 minutes. A sample portion was transferred to a clean polyethylene bottle for storage. The fluoride concentration in the samples was determined with a fluoride ion specific electrodea and a sleeve junction calomel reference electrode connected to a digital electrometer.b The buffer suggested by McCann (Arch Oral Biol 13: 475577, 1968) for pH and ionic strength adjustments were used in a 1:1 dilution of all samples (Applications Bulletin No. 5, Orion Research Inc., Cambridge, Mass, 1967). All measurements were made at room temperature by recording the stabilized potential. The standards were dilutions of a standard fluoride solutionc in deionized water. The fluoride concentrations observed before and after boiling for each container and the change in fluoride concentrations are shown in the illustration. A pronounced increase was seen with the Teflon-coated vessel. The boiled water from the aluminum vessel showed notable decrease. Little change was noted in the fluoride

ABO Phenotypes and Periodontal Disease

The relative liability of some blood group phenotypes to certain diseases has been investigated throughout most of this century; this has resulted in a large accumulation of literature (C. A. CLARKE, Progr Med Genet 1:81119) and a degree of controversy (A. S. WEINER, Am J Hum Genet 22:476-483, 1970). Periodontal disease has been considered in respect to this and variable findings have been reported. In 1927 Weber and Pastern reported their study of 369 German periodontal patients; they found a preponderance of individuals with type A blood and a relative absence of those with type 0 (Dtsch Monatsschr Zahnheilkunde 14:704-709, 1927). Polevitsky generally confirmed their findings (K. POLEVITSKY, J Dent Res 9:285, 1929); however, Barros and Witkop found no difference between expected and observed numbers in a Chilean population (Arch Oral Biol 8:195-206, 1963). A recent report of a study based on eleven periodontosis patients noted that patients with type A blood had more widespread and severe bone loss than patients with type B (R. S. KASLICK, A. I. CHASENS, M. A. TUCKMAN, and B. KAUFMAN, J Periodontol 42:420427, 1971). An investigation of the influence of blood group polymorphisms on periodontal disease was begun in 1970 with a random sample of clinic patients at the University of Nebraska. There were 151 individuals, 67 males and 84 females, between the ages of 18 and 74 (mean age, 29.9 years). Oral examination included evaluation of plaque, calculus, and periodontal disease under standardized conditions by a

Mesiodistal gradient of mandibular precedence in the developing dentition.

In postnatal dental development, there are clear-cut mandibular-maxillary eruption precedences; usually the mandibular incisors tend to precede their maxillary opponents. There is also a mesiodistal gradient of mandibularmaxillary precedence such that maxillary precedence becomes both relatively and absolutely more common in the posterior teeth (H. IsRAEL, A. DAHLBERG, S. M. GARN, and R. KEREWSKY, J Dent Res 46:456, 1967; and H. IsRAEL, S. M. GARN, and R. F. BENITEZ, Arch Oral Biol 13:239-241, 1968). It is not known, however, whether such precedent polymorphisms exist in prenatal dental development and whether they have their origins in the first trimester of existence. To test this possibility, the relative development of maxillary and mandibular deciduous opponents in a series of 52 human embryos, all below 58 mm in crown-rump length, was examined. The developmental status of each tooth was assessed individually and described by a numerical code; the results were incorporated on standard IBM 80-column punch cards. Then for each pair of opponents, dental development was categorized as (1) mandible

Effect of agenesis on the crown-size profile pattern.

Agenesis and hypodontia are associated with crown-size reduction in the remaining teeth (S. M. GARN ET AL, J Dent Res 41:717, 1962, Nature 200:488-489, 1963; J Dent Res 42:13441363, 1963; H. J. KEENE, Amer J Orth 50: 445-451, 1964; and K. HANIHARA ET AL, J Anthrop Soc Nippon 73:72-81, 1965). The question arises as to whether crown-size reduction associated with tooth number reduction is uniform throughout the remaining teeth or whether there is differential reduction in tooth material that results in a distinctly different crown-size profile pattern. In order to answer this question we measured the mesiodistal crown diameters of 658 subjects, including 82 with third molar agenesis and 19 with radiographically verified agenesis of multiple teeth. The original measurements were converted into sex-specific t-scores using a computer program (C. R. BLACK, Ann NY Acad Sci 134:538-540, 1966). The crown-size profile patterns were then compared using the statistic rT as previously described (S. M. GARN ET AL, J Dent Res 47:1190, 1968: Arch Oral Biol 13:1235-1242, 1968: Amer Anthrop 71: 79-84, 1969). As shown in the table, the crown-size profile pattern of individuals lacking one or more mandibular third molars is distinctly different from that of the total group (r=-0.34). Sim-

Genetic basis of the crown-size profile pattern.

Although genetic control of crown diameters has been documented by a number of workers (R. H. OSBORNE ET AL, Amer J Hum Genet 10: 350-356, 1958; S. M. GARN ET AL, J Dent Res 44:228-242, 1965; D. W. LEWIS and R. M. GRAINGER, Arch Oral Biol 12:539-544, 1967; and D. H. GOOSE, J Dent Res 46:959-962, 1967), genetic involvement in crown-size patterning has not been ascertained for the whole dentition. To investigate the genetic and chromosomal basis of crown-size profile patterning, crownsize patterns of 960 pairs of subjects from southwestern Ohio were compared. After converting individual measurements into normalized T scores (W. A. MCCALL, Measurement, 1939, pp 505-508) by using a computer program (C. R. BLACK, Ann NY Acad Sci 134: 538-540, 1966), dentitions of each pair of subjects were compared by the product moment correlation, r. The resulting correlation coefficients (rT), involving T-scored values of corresponding teeth, provided a simple expression of the degree of patterned similarity between any two individuals. The use of normalized T scores automatically corrected for sex made possible cross-sexed as well as like-sexed comparisons. Sibling correlations for tooth-size similarity approximated 0.22 for 246 like-sexed and crosssexed brothers and sisters (Table). Parent-child similarities in crown-size profile pattern approximated 0.20 as shown by 90 parent-child pairings. Similarly investigated, 58 pairs of cousins yielded a mean similarity coefficient value of 0.15. Finally, randomly paired, unrelated subjects had a pattern profile similarity value of 0.01, close to the theoretical 0.00 value. With profile-pattern similarity values ranging from 0.90 for monozygotic female twins through 0.20 for parents versus their children, 0.15 for cousins, and 0.00 for unrelated pairs, it is clear that crown-size profile patterns have a genetic basis. The values in the table also show evidence for X-chromosomal involvement in the pattern of the total dentition. Sister-sister values of rT exceeded the remaining sibling correlations.