Biography:

In the past Edward F. Harris has collaborated on articles with Isaac Kaplan and Joseph A. Walker. One of their most recent publications is Original articleA study of occlusion and arch widths in families☆. Which was published in journal American Journal of Orthodontics.

More information about Edward F. Harris research including statistics on their citations can be found on their Copernicus Academic profile page.

Edward F. Harris's Articles: (14)

Original articleA study of occlusion and arch widths in families☆

AbstractIt is often claimed that occlusal variation (“malocclusion”) is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Original articleA study of occlusion and arch widths in families☆

AbstractIt is often claimed that occlusal variation (“malocclusion”) is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Original articleA study of occlusion and arch widths in families☆

AbstractIt is often claimed that occlusal variation (“malocclusion”) is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Original articleA study of occlusion and arch widths in families☆

AbstractIt is often claimed that occlusal variation (“malocclusion”) is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Original articleA study of occlusion and arch widths in families☆

AbstractIt is often claimed that occlusal variation (“malocclusion”) is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Microleakage of composite resin and glass ionomer cement restorations in retentive and nonretentive cervical cavity preparations

AbstractKetac Fil glass ionomer cement (GIC) and Scotchbond 2 dentinal bonding agent (DBA)/Silux Plus composite resin restorations were inserted in cervical cavity preparations of extracted human teeth. After thermocycling, the specimens were invested and sectioned longitudinally and horizontally through the center of the restoration. Microleakage was evaluated as a ratio of the extent of methylene blue dye penetration at the tooth-restoration interface. Although all restorations exhibited leakage, both the GIC and bonded composite resin restorations recorded less leakage in retentive than in nonretentive cavity preparations. Composite resin restorations in nonretentive cavity preparations showed significantly more dye penetration toward the pulpal chamber than the GIC restorations. Ketac Fil GIC restorations inserted without a matrix strip exhibited less leakage than those with a matrix strip. The most desirable results were recorded with Scotchbond 2 DBA/Silux Plus composite resin restorations in retentive preparations.

Original articleThe enkephalin response in human tooth pulp to orthodontic force

AbstractPublic perception is that dentistry and pain go hand in hand; thus, pain and pain control are important considerations to the profession. Recent studies have attempted to discover the precise metabolic events involved in neural transmission of nociceptive information. One focus has been the study of peptidergic pathways, which purportedly inhibit the firing of pain-conducting fibers. The research described in this article defined the existence of one enkephalin, methionine enkephalin (ME), in an extract of human tooth pulp tissue and the effect of orthodontic force on that ME concentration. One set of patients who had premolars extracted for orthodontic purposes served as controls. Another set, also diagnosed for premolar extractions, had a coil spring attached between the left and right maxillary premolars to supply an orthodontic force for a period of time prior to extraction. High-performance liquid chromatography, radioimmunoassay, radioreceptor assay, and mass spectrometry were used in a series of experiments to isolate, identify, and quantify ME in the pulp tissues. Principal results were as follows: (1) for the first time ME was detected in human tooth pulp, (2) orthodontic force caused a significant decrease in ME concentrations in the group of experimental teeth compared with controls, and (3) ME levels of the first spring-attached tooth that was removed from each patient had a statistically significant inverse log-linear relationship to the amount of applied force. These data indicate that orthodontic force mobilizes at least one neuropeptidergic pathway in the human tooth pulp.

Heritability of craniometric and occlusal variables: A longitudinal sib analysis

There has long been interest in the inheritance of malocclusion, but few studies have distinguished between skeletal (craniometric) variables and occlusal, tooth-based variables (e.g., anterior irregularity, rotations, displacements). This study was based on serial assessments of untreated persons in 30 sibships from 4 years (full deciduous dentition) to 20 years of age (full permanent dentition) in the Bolton-Brush Growth Studies of Ohio. Results define a clear dichotomy: craniometric variables (k = 29) typically show significant additive components of variance; correlations increase from age 4 to age 20; and correlations average 0.43 at adulthood. Tooth-based variables of position and relationship (k = 21) reach significance only occasionally; correlations decrease with age to the extent that few variables for subjects at age 20 have a correlation significantly different from zero. In contrast to craniometric variables, which have high heritabilities, almost all of the occlusal variability is acquired rather than inherited.

Age effects on orthodontic treatment: Skeletodental assessments from the Johnston analysis*

We have compared differences in treatment outcomes dependent on patient age, either adolescent (x̄ = 12.5 years at start) or adult (x̄ = 27.6). Subjects were female patients whose Class II, Division 1 malocclusions were treated with Tweed edgewise mechanics and four-premolar extractions. Cephalometric records were assessed according to the Johnston analysis. The functional occlusal plane remained stable during mechanotherapy in the adolescents, whereas it steepened considerably in the adults. Differential mandibular growth in adolescents contributed 70% of the total molar correction, with orthodontic tooth movement accounting for the other 30%. Maxillary growth in the adults detracted from the Class II molar correction; tooth movement accounted for virtually all of the correction.

Maxillary incisor crown-root relationships in different Angle malocclusions

The long axis of the maxillary incisor root is not always identical to that of the crown. Instead, there is appreciable variation in the crown-root angle, generally with the crown torqued lingual to the root axis. In orthodontic cases assessed before and at the end of full-banded treatment, the crown-root angle was significantly deflected in the Class III molar relationship series, notably so in moderate to severe cases where the maxillary incisors are constrained lingual to the lower arcade. Apical root resorption was not significantly associated with the crown-root angle before or after comprehensive orthodontics. Cephalometric predictors of the amount of deflection of the crown-to-root axis were localized to intertooth relationships (overjet, interincisal angle). It is proposed that the large collum angles in Class III cases develop during tooth eruption when the maxillary incisors are trapped within the lower arch; this torques the crown of the maxillary incisor but leaves the unmineralized portion of the root free to develop as if the crown were still in its prior, more procumbent orientation.

Bilateral asymmetry of tooth formation is elevated in children with simple hypodontia

AbstractObjectiveTooth formation normally progresses symmetrically between sides; the goal in this study was to test the clinical impression that left–right asymmetry in tooth formation is elevated in children with simple hypodontia.Materials and methodsData from panoramic X-rays of American white children (5–14 years of age) with simple hypodontia (n = 158) were compared to a comparable group from the same practises with all teeth present (n = 206). Children with hypodontia were otherwise phenotypically normal, with no cleft or recognized syndrome. Crown–root formation of each tooth (ignoring third molars) was scored using an 11-grade scheme. Analysis relied on chi-square goodness-of-fit tests and odds ratios.ResultsHypodontia typically occurs unilaterally; it is more common in girls than boys; and it most frequently affects second premolars (omitting third molars). No evidence of a side preference was found as regards absence of the tooth or tooth formation. Tooth formation was decidedly more frequently asymmetric in those with hypodontia, though again the distribution by side was random in the sample. Summed over all tooth types, asymmetric formation occurred in 18.6% of cases with hypodontia compared to 11.9% in controls, and this is significant by chi-square (P = 0.03), with an odds ratio of 1.43 (CL: 1.02, 2.04). All tooth types exhibit elevated developmental asymmetry in the hypodontic sample despite only one or a few teeth being agenic.ConclusionsIncreased asymmetry suggests a breakdown in the rigour of developmental timing in cases with simple hypodontia. In concert with increased frequencies of other growth issues in such cases, such as side differences in size and morphology, hypodontia is best viewed as a symptom of an anatomically broad relaxation of developmental canalization between homologous structures, not an isolated dental feature.

The premaxillary-maxillary suture and orthodontic mechanotherapy***

Even though there has been debate over whether a separate premaxilla exists in the human being, it has been suggested that the premaxillary-maxillary suture remains patent into adolescence and provides an explanation for the action of certain orthodontic and orthopedic appliances. To assess whether this suture is pertinent to an understanding of appliance effects, the skulls of 50 subadult subjects were scrutinized to determine patency with regard to age. Remnants of a premaxillary-maxillary suture may be present on the surface of the palate at all ages studied, and often this suture extends deep to the surface. However, in no case was the suture continuous so as to distinguish a distinct premaxilla. These findings disprove the claim that the premaxillary-maxillary suture system provides an explanation for any form of orthodontic or orthopedic therapy.

Original articleInfluence of tooth crown size on malocclusion

IntroductionMalocclusion is an increasingly common, multifactorial problem. The most prevalent malocclusion results from excess tooth size compared with the size of the supporting bone; this creates a tooth-size arch-size discrepancy. Although the causes of malocclusion are obscure in most instances, a contributing factor appears to be tooth size. The goal of this study was to test whether the dimensions of the crowns of the permanent teeth differ in young men with naturally good occlusions compared with those who required orthodontic treatment.MethodsTooth crown dimensions (mesiodistal and buccolingual) were measured in 2 samples of American white men. One group (n = 42) had naturally good occlusion; the other group (n = 90) required orthodontic treatment to correct tooth-size arch-size discrepancy.ResultsThe means of 23 of the 24 tooth crown dimensions—involving the 14 tooth types (central incisor through first molar) in both arches—were significantly larger in subjects with malocclusions than in those with good occlusions. Multivariable analysis showed that mesiodistal size of the maxillary lateral incisor was the most significant difference between the 2 samples, but this might reflect the composition of the sample (maxillary lateral incisor size is notoriously variable in white men).ConclusionsTooth size is not necessarily the foremost cause of malocclusion in a patient, but it should be evaluated.

A longitudinal study of arch size and form in untreated adults

Adulthood—the lengthy phase following attainment of biologic maturity—often is perceived as a period of “no change” or one of slow deterioration. Recent skeletodental studies discount this stereotype. Changes in arch size and shape were studied here in a longitudinal series of 60 adults with intact dentitions. Full-mouth study models were taken at about 20 years of age and again at about 55 years. Some variables—particularly those between arches (incisor overbite and overjet, molar relationship) and mandibular intercanine width—remained age-invariant. In contrast, all other measures of arch width and length changed significantly (P<0.01): Arch widths increased over time, especially in the distal segments, whereas arch lengths decreased. These changes significantly altered arch shape toward shorter-broader arches. The data suggest that changes during adulthood occur most rapidly during the second and third decades of life, but do not stop thereafter. Possible mechanisms driving these changes in tooth position are discussed.

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