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Biomedical subjects

E F Harris

Publications and source records attributed to E F Harris.

At least 37 records · Page 2Linked to original sources
PubMed1997

Relapse revisited.

Rather little is known about the changes in orthodontic treatment results exceeding a decade after treatment. The purpose of this study was to quantify changes in tooth relationships in a series of cases (n = 36) at 6 years and again at 15 years after treatment. The rate of change decreased with time, supporting the contention that most "relapse" occurs soon after treatment; continued change generally cannot be distinguished from normal aging processes that occur, regardless of whether a person had been treated orthodontically. There were minor, but statistically significant, associations between increased incisor irregularity ("relapse") and parasagittal growth of the jaws. Greater irregularity occurred when mandibular growth exceeded that of the maxilla, decreasing overjet and crowding the lower incisors within the containing arch of the maxilla. Overall, relapse tended to be less in these cases treated by a single experienced specialist that in university-based samples treated by multiple, orthodontic residents.

Adolescent↗
PubMed1997

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.

Adult↗
PubMed1995

Adult versus adolescent Class II correction: a comparison.

The interest of the adult patient in orthodontics has increased as the demographics of the specialty of orthodontics has changed. There are major intreatment and posttreatment differences in Class II malocclusion correction between the adolescent and the adult. This article outlines the differences--and the similarities--between adolescent and adult Class II malocclusion correction. The differences and similarities are illustrated with case reports of a representative adolescent from the adolescent group and a representative adult from the adult group.

Adolescent↗
PubMed1994

Clinical ramifications of posterior and anterior facial height changes between treated and untreated Class II samples.

Some clinicians have suggested that one primary difference between successful and unsuccessful Class II treatment outcomes is the relative change of anterior and posterior facial heights. Successfully treated cases are claimed to exhibit greater increases in posterior facial height (PFH, articulare to gonion) than in the anterior facial height (AFH, menton to palatal plane). This conjecture was tested here by recalling a treated Class I sample and a treated Class II sample and by comparing the differences found in these samples to an untreated Class II sample at the same ages. The PFH/AFH ratio increased significantly more in the treated Class I and Class II samples during the active phase of treatment than in the untreated Class II sample at the same ages. During the years from posttreatment to recall (mean = 6 yrs), there was a significant increase in the PFH/AFH ratio in the treated Class II sample due to a greater increase in PFH than AFH. This ratio continued to improve after all appliance therapy had been discontinued, and it did not occur in the treated Class I sample nor in the untreated Class II sample. The conclusion was that the patient with a Class II malocclusion, if treated, continues to change favorably over time. This favorable change, in turn, helps maintain the Class II correction.

Adolescent↗
PubMed1994

Effects of patient age on postorthodontic stability in Class II, division 1 malocclusions.

The increase in the proportion of adults in the typical orthodontic practice merits closer scrutiny of the treatment differences involved in adult vis-à-vis adolescent patients. Orthodontic treatment in the adolescent relies heavily on growth; in the adult, the practitioner must reposition teeth within the nongrowing arches. This difference may create the potential for greater postretention relapse in the adult; alternatively, continued growth in the subadult might detract from stability of the case. Two samples of Class II, Division 1 cases, all treated by one specialist, were examined an average of 5 years out of treatment. One group had been treated during adolescence (approximately 12 years of age), the other in adulthood (approximately 28 years). The orthodontic corrections were stable in both groups, but for different reasons: Posttreatment changes in the bony and dental structures of the adults were minimal. Bony changes (i.e., continued midface and mandibular growth) were appreciable in adolescents, and this growth--notably growth of the mandible--compensated for unfavorable drift of the dental elements (primarily mesial shift of the maxillary molar) after treatment. In sum, orthodontic corrections in adults were found to be at least as stable as those in the conventional adolescent patient.

Adolescent↗
PubMed1994

Apical root resorption in orthodontically treated subjects: analysis of edgewise and light wire mechanics.

Of the several modes of tooth movement, pressure from intrusive forces seems the most likely to cause external apical root resorption (EARR). This has been demonstrated for incisors in human beings and molars in laboratory animals. The present study examined full-banded adolescent patients and scored the degrees of in-treatment root resorption throughout the dentition. Just Class I cases with four first premolar extractions were used. Equal samples of conventional Begg and Tweed treated cases were examined with 1:1 sex ratios (total n = 83). No difference between the Begg and Tweed techniques and no sex difference was found in any of the 30 univariate tests, even though power analysis indicated a strong likelihood of finding a difference if one existed. By using multiple linear regression, significant decreases in length (EARR) were found for those roots systematically intruded in this Class I malocclusion, notably the mesial root of the maxillary first molar and the distal root of the mandibular first molar. Even though some of the present cases had been in "active" treatment up to 6 years, we found no significant association between duration of treatment and degree or amount of EARR.

Adolescent↗
PubMed1994

Skeletodental changes in the adolescent accruing from use of the lip bumper.

Cast and cephalometric analyses were performed to measure the effects of treatment with a lip bumper. The lip bumper was fabricated from an 0.045 inch wire with shrink tubing and no acrylic shields. Nine of the 32 patients were evaluated two years after the comprehensive phase of treatment. Patients were in the mixed dentition stage of development (mean age of 9.9 yrs). A single orthodontist designed all the appliances and treated all the cases. There was significant expansion between the canines, first premolars, second premolars and molars, with the greatest expansion occurring between the first premolars. Cephalometric analysis revealed that the molars underwent angular uprighting but did not move bodily. Incisor irregularity decreased 60% during this phase of treatment. The retention cases revealed that the arch depth decreased, perhaps due to loss of leeway space, but arch widths all were broader, especially in the anterior segment, than at the end of the lip bumper phase. Incisor irregularity also remained trivial (x = 0.3 mm), suggesting appreciable stability.

Adolescent↗
PubMed1994

Posttreatment stability in adult and adolescent orthodontic patients: a cast analysis.

Orthodontic treatment of adults differs in many ways from that of the conventional adolescent patient. Adults are essentially nongrowing and have lower turnover rates of alveolar bone. These and other factors may affect the posttreatment stability of adult dentitions. This study compared the stability of orthodontic outcomes in matched samples of adolescents (about 13 years of age) and adults (about 30 years old) at an average of 5 years out of treatment. Analysis disclosed few differences between age groups; both exhibited considerable stability. Regarding key treatment considerations--such as midline alignment, incisor overbite and overjet, incisor irregularity, and molar relationship--both groups changed to equivalent degrees (and very little on average). Although minor differences were found (eg, arch length decreased more in adults), treatment changes in this sample of adults were at least as stable as those in the adolescents for all clinically relevant variables.

Adolescent↗
PubMed1993

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.

Adolescent↗
PubMed1993

Heritability of cephalometric and occlusal variables as assessed from siblings with overt malocclusions.

It has been thoroughly documented that measurements of the craniofacial complexes have moderate to high heritabilities--that they are primarily a consequence of "nature" rather than "nurture." In contrast, recent studies, which used twin and sibship analyses, have shown that malocclusions per se (i.e., measures of tooth position and dental interrelationships) have low heritabilities; malocclusions sensu stricto are primarily acquired (environmentally induced), not inherited. All such studies have, however, focused on persons not treated orthodontically. This can introduce selection bias since cases with moderate to severe malocclusions would have received treatment and, thus, be excluded from study. The present analysis addresses this issue of ascertainment bias by examining just that portion of the adolescent population receiving comprehensive orthodontics. Initial treatment records of 104 pairs of siblings were studied, all of whom subsequently received full-banded treatment. In this selected series of overt malocclusions, heritability estimates for craniometric variables were significantly lower than in a comparable series of adolescents with naturally occurring good occlusions, whereas heritability estimates for occlusal variations (e.g., rotations, crossbites, displacements) were significantly higher. This vindicates the clinical perception that siblings often present with similar malocclusions. We propose that the substantive measures of intersib similarity for occlusal traits reflect similar responses to environmental factors common to both siblings. That is, given genetically influenced facial types and growth patterns, siblings are likely to respond to environmental factors (e.g., reduced masticatory stress, chronic mouth-breathing) in similar fashions. Malocclusions appear to be acquired, but the fundamental genetic control of craniofacial form often diverts siblings into comparable physiologic responses leading to development of similar malocclusions.

Adolescent↗
PubMed1993

Anabolic steroids and craniofacial growth in the rat.

Anabolic steroids are misused by adolescents as well as adults to increase muscle and improve appearance and athletic performance. Since these substances strongly enhance protein synthesis, it was speculated that craniofacial changes in bone size and, perhaps, skeletodental relationships might also occur. Eighty rat pups were divided into three groups: (1) sham-treated controls, (2) a low-dose group (1 mg/kg/wk nandrolone phenpropionate), and (3) a high-dose group (10 mg/kg/wk). The high-dose regimen more closely mimics dosages used by abusers. Steroid therapy significantly increased all measures of the craniofacial complex (k = 20)--on the order of 3.5%-except some precocious calvarial dimensions. Importantly, significant alterations also occurred in facial morphology. The low-dose group exhibited proportionate increases in most craniofacial dimensions, but the high-dose produced overt shape changes, notably a maxillomandibular, anteroposterior jaw discrepancy due to maxillary excess. In sum, this anabolic steroid significantly altered facial growth in this animal model; by extension, steroid abuse by adolescent humans may produce discernible changes in their craniofacial complexes.

Anabolic Agents↗
PubMed1993

Size and form of the cranial base in isolated cleft lip and palate.

Most cases with cleft lip and palate (CLP) have no other obvious malformation and are termed isolated CLP. The implication is that these individuals experienced a time-specific and anatomically-localized disturbance during palatogenesis but are otherwise normal. The cranial base was studied from cephalograms in subadults with isolated CLP (n = 43) to test for alterations in size and shape. Controlling for age and gender, analyses showed no size difference, but flexure of the cranial base was significantly greater in the CLP group. Taken in conjunction with increased risks of other conditions with prenatal onsets, it appears that "isolated CLP" is a misnomer and the cleft should be viewed as an overt manifestation of a more generalized growth disturbance.

Adolescent↗
PubMed1993

An analysis of causes of apical root resorption in patients not treated orthodontically.

With few exceptions, most cases of external apical root resorption have no evident etiology, particularly when root blunting from orthodontic treatment has been ruled out. This study determined the frequency of apical root resorption in the permanent dentition of patients who had not been treated orthodontically. Associations between the occurrence of external apical root resorption and three measures of oral health--number of missing teeth, periodontal probing depths, and alveolar crestal bone heights--were also examined. Between 7% and 10% of the 306 patients exhibited obvious apical resorption. Strong statistical associations were found between the occurrence of external apical root resorption and loss of teeth, increased periodontal probing depths, and reduced crestal bone heights; ie, root resorption was significantly more common in teeth with compromised support. Loss of stability from adjacent teeth, increased use of fewer remaining teeth, and loss of the root's anchorage in the bone are significant predictors of external apical root resorption.

Adolescent↗
PubMed1993

The A.B.F.O. study of third molar development and its use as an estimator of chronological age.

Radiographs depicting third molars (M3s) have been used to estimate chronological age in juvenile and adult suspects, but accuracy of the method has been in question. This study provides age benchmarks for American whites (age range: 14 to 24 years) based on cases (n = 823) drawn from diplomates of the American Board of Forensic Odontologists in the United States and Canada. Maxillary M3 formation was slightly advanced over mandibular M3s, and root formation occurred earlier in males than females. Mean and median ages for M3 formation are tabled using Demirjian's eight-grade classification. Regression formulas and empirical probabilities are provided relative to the medicolegal question of whether an individual is at least 18 years of age. The M3 is the most variable tooth in the dentition, but situations arise where M3 formation is the only usable datum for age estimation.

Adolescent↗
PubMed1993

Anabolic steroid abuse and tooth size-arch dimensions in the rat.

Anabolic steroids are misused by adolescents and adults to increase muscle mass and improve appearance and athletic performance. Since anabolics strongly enhance protein synthesis, it was speculated that alterations in tooth size and arch length could occur. This study quantified the effects of the anabolic steroid nandrolone phenpropionate on these parameters in a rat model. The steroid significantly increased mandibular arch length. No difference in mesiodistal dimensions of the molars occurred. In consequence, the increased arch dimensions combined with unaltered tooth size may result in dental spacing and/or other malocclusions.

Analysis of Variance↗
PubMed1993

Dental health patterns in an urban Midsouth population: race, sex and age changes.

Little is known about the oral health of American blacks. In particular, have they experienced the same reductions in dental caries and improvements in oral health as has the majority culture during the past several decades? A contemporary series of patient records (n = 300) was examined to test for age, sex, and race (American black and white) differences in an urban Midsouth population. Tooth loss was strongly age progressive in blacks and whites, but the rate was much greater in blacks. Periodontal probing depths also tended to be greater in blacks, particularly for the maxillary anterior teeth. The pattern of tooth loss with age in blacks is similar to rates recorded for the whole United States in the early 1960s. Subsequently, whites have tended to experience substantial improvements in oral health (ie, fewer decayed, missing, and filled teeth and less tooth loss); blacks in this sample have not exhibited this improvement.

Adolescent↗
PubMed1992

Metacarpophalangeal length changes in humans during adulthood: a longitudinal study.

Total lengths of the 19 diaphyseal hand bones were measured from standardized radiographs of healthy American whites as young adults (ca. 21 years) and again at ca. 55 years of age. The four hand-bone rows exhibit distinctive length changes: Distal and middle phalanges continue to increase significantly in length, proximal phalanges constitute a transition zone of little change, and metacarpals uniformly decrease in length. Clear-cut sex differences are noteworthy: Males change more (lose more in some bone rows, gain more in others) than females. Progressive elongation was greatest in the distal phalanges where apposition around the distal aspect ("tufting") is not constrained by a joint or epiphysis. Loss of bone length in the metacarpals by subchondral resorption is consistent with documented reductions in activity levels and grip strength with age, as well as diminished joint spaces which alter loading of the joints.

Adult↗