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Biomedical subjects

Mark G Hans

Publications and source records attributed to Mark G Hans.

12 recordsLinked to original sources
PubMed2007

Correlations between cephalometric and facial photographic measurements of craniofacial form.

INTRODUCTION: The purpose of this study was to compare craniofacial measurements from cephalometric radiographs with analogous measurements from standardized facial photographs. METHODS: The sample consisted of 326 subjects (168 white, 158 black) enrolled in a genetic epidemiological family study of sleep behavior. Traditional lateral cephalograms and standardized facial photographs were taken of each subject. Three angular, 3 linear, total face height, and lower face height cephalometric measurements were compared with 4 angular and 4 linear measurements from standardized photographs. Descriptive statistics for all measurements in the entire sample and for the racial subgroups were computed. Pearson product moment correlation coefficients were computed between analogous measurements, and intraclass correlation coefficients were calculated from repeated measurements on the photographs. RESULTS: The reliability of the photographic technique was excellent, with all measurements having intraclass correlation coefficients above 0.90. However, the correlations between analogous photographic and cephalometric measurements were lower and varied between 0.356 and 0.643. The highest correlations were observed for lower facial height and mandibular length, 0.643 and 0.562, respectively. In the black group, the correlations between cephalometric and photographic measurements of mandibular length and lower facial height were 0.676 and 0.690, respectively. Both were higher than those for white subjects, 0.399 and 0.577, respectively. CONCLUSIONS: Both linear and angular measurements useful for characterizing facial morphology can be reliably measured from facial photographs. However, only moderate correlations with analogous cephalometric measures were found. Therefore, standardized photographs and cephalograms most likely measure different aspects of facial morphology and cannot be used interchangeably. Cephalometrics remains the method of choice for clinical patient care, whereas photographs might be better for large-scale epidemiological studies, especially if there is a need for a low-cost, noninvasive method that be used in diverse clinical and field settings.

Black People↗
PubMed2006

Hydrostatic pressure increases apoptosis in cartilage-constructs produced from human osteoarthritic chondrocytes.

Tissue-engineering is considered a promising avenue for developing human articular cartilage implants that can be employed for resurfacing damaged cartilage in the early stages of osteoarthritis. In the present study, human cartilage-constructs were produced from human osteoarthritic chondrocytes maintained on a scaffold of HYAFFR-11 in perfusion mini-bioreactors or after implantation and recovery from nude or SCID mice after 3 weeks. The human cartilage-construct extracellular matrix reacted positively with anti-Type II collagen monoclonal antibody, but not with anti-Type I or anti-Type X collagen monoclonal antibodies. A significant portion of the cartilage-construct extracellular matrix stained metachromatic with Toluidine blue-O indicative of sulfated-proteoglycan deposition. Cyclic hydrostatic pressure applied for 4 hrs at 5 MPa using a 1 Hertz sinusoidal frequency significantly increased (p < 0.02) the proportion of apoptotic cells in the cartilage-constructs (41% +/- 4.2%; mean +/- SD) compared to control cartilage-constructs (28.5 +/- 8.4%).

Animals↗
PubMed2006

A comparison of scanned lateral cephalograms with corresponding original radiographs.

INTRODUCTION: Digital cephalometric radiography is gaining popularity in orthodontic practices. However, few studies have compared measurements and superimpositions on analog radiographs with those made on scanned digital images. The objectives of this study were to evaluate distortion associated with scanning lateral cephalograms and printing to hard copy, and to assess the accuracy of digital images for regular cephalometric tasks. METHODS: Pretreatment and posttreatment cephalograms from 30 subjects were selected and 3 groups were created: original, digital, and hard copy. All films had 8 fiducial marks punched and were scanned at 150 dots per inch. The hard copies were created with a laser printer. Twenty-three cephalometric measures and 3 superimpositions were evaluated for distortion, measurement accuracy, and superimposition results. Paired t tests were used to assess statistical significance. RESULTS: Distortion between the original and the scanned image showed 0.8 mm vertical enlargement and 0.4 mm horizontal reduction. Printed radiographs had 1.1 mm vertical and 0.4 mm horizontal enlargement. All differences were statistically significant. Cephalometric comparisons between original and digital images showed statistical differences in Frankfort horizontal (FH)-occlusal plane, maxillary central incisor-FH, facial plane, y-axis, Frankfort plane to mandibular plane angle (FMA), and FH-Naison to point A (NA). Significant differences also were found in facial plane, y-axis, FMA, and FH-NA when comparing the digital and the hard-copy images. All measurements with differences contained the landmarks porion and orbitale. No differences were found between the original and the hard-copy images. Likewise, no significant differences were found between the original and the digital superimpositions. CONCLUSIONS: Although some distortion was found, the relatively small horizontal and vertical discrepancies were deemed clinically insignificant. Landmark identification errors on scanned images contributed to the discrepancies in cephalometric analysis. Therefore, for clinical orthodontic applications, scanned cephalograms can be used. However, caution must be exercised when determining porion and orbitale.

Artifacts↗
PubMed2006

Cephalometric changes in overbite and vertical facial height after removal of 4 first molars or first premolars.

INTRODUCTION: The objective of this study was to evaluate the outcome of standard edgewise orthodontic treatment with extraction of 4 first molars (6xT group) or Tweed edgewise treatment with extraction of 4 first premolars (4xT group). MATERIALS AND METHODS: A cephalometric analysis that isolated tipping and bodily tooth movements of the maxillary and mandibular incisors and measured vertical skeletal changes in the anterior region of the maxilla and mandible was used. Thirty subjects treated by 10 practitioners comprised the 6xT group, whereas 31 subjects treated in the Case Western Reserve University orthodontic clinic were used in the 4xT group. Control groups (6xC and 4xC) were selected from untreated subjects enrolled in the Bolton-Brush Growth Study and were matched on age and gender. Data were collected before (T1) and after (T2) treatment. RESULTS: Analysis of the data showed no statistically significant changes between 6xT and 6xC for any of the variables studied. An increase in overbite of 2.1 mm in the 6xT group was the result of small but clinically significant changes in both tipping and extrusion of maxillary and mandibular incisors. In the 4xT group, statistically and clinically significant changes were observed for intrusion of the maxillary and mandibular incisors, resulting in a 4.1-mm decrease in overbite. Importantly, both the 6xT and the 4xT groups showed no increase in mandibular vertical height during treatment. CONCLUSION: Both treatment strategies showed good control of vertical mandibular growth. Bodily intrusion of anterior teeth was the main contributor to correction of deep overbite in the Tweed edgewise sample.

Bicuspid↗
PubMed2006

Correction of a canted occlusal plane with miniscrews in a patient with facial asymmetry.

The inability of orthodontists to change the cant of the maxillary occlusal plane without surgical intervention is a limitation of orthodontic treatment. LeFort I osteotomy with asymmetric maxillary impaction is often used to correct this problem. However, canting caused by extruded teeth can be corrected easily with normal orthodontic appliances and skeletal anchorage. The correction occurs through intrusion of the extruded teeth on 1 side of the maxilla, thereby avoiding a more aggressive surgical approach. A 22-year-old Korean man with facial asymmetry and mandibular prognathism treated in this manner showed the possibility of correcting occlusal plane canting with miniscrews.

Adult↗
PubMed2005

A longitudinal 3-dimensional size and shape comparison of untreated Class I and Class II subjects.

BACKGROUND: The invention of the Broadbent-Bolton cephalometer in 1925 made possible the collection of 3-dimensional data from biorthogonal plain film head radiographs. The objective of this study was to compare longitudinal changes in the shape and size of craniofacial structures between 16 untreated Class II Division 1 girls and 16 untreated Class I Bolton girls. METHODS: Procrustes analyses were used to compare differences in 30 cephalometric landmarks that were 3-dimensional. The same methods were also used to analyze changes of 4 subsets of landmarks (maxilla, mandible, midface, and cranial vault). Comparisons included shape and size differences between adjacent age groups at ages 6, 11, and 15 in the Class II sample as well as between the Class I and Class II samples at each age. RESULTS: Overall, the craniofacial complex underwent continuous shape change from ages 6 to 15 in both samples. In the Class II sample, the smallest contribution to craniofacial shape change was seen for the mandibular landmarks between ages 6 and 11. Compared with the Class I sample, the Class II sample had (1) a longer facial pattern, (2) the smallest mandibular shape difference at age 6 and the largest at age 15, and (3) more protrusive maxillary landmarks at all ages compared with the Class I sample. The Class II sample also had the largest change in size from ages 11 to 15 (6.5%), whereas the Class I sample showed the greatest size change (10.5%) from ages 6 to 11. CONCLUSIONS: Clinically significant size and shape differences were observed during growth and development between Class II and Class I subjects in this sample.

Adolescent↗
PubMed2004

Comparing orthodontic treatment outcome between orthodontists and general dentists with the ABO index.

This study used the American Board of Orthodontics (ABO) Objective Grading System (ABO index) (ABOI) to compare treatment outcome between patients treated by orthodontic specialists (OS) and patients treated by general dentists (GP). The sample (n = 196) consisted of 126 dental casts of patients treated by OS and 70 treated by GPs. All casts were collected in 1997 and 1998 from 10th grade students attending high schools in Cuyahoga County, Ohio, and were scored by 1 operator (Y.A.) calibrated in the use of the ABOI. The mean ABOI score for the OS group was 26.0 +/- 11.4 compared with 29.6 +/- 12.8 for the GP group. This difference was significant at the P < or = .05 level. Of the 7 components used in the ABOI, alignment of teeth was found to be the most significant between groups (OS mean = 5.39 +/- 4.37 versus GP mean = 7.8 +/- 5.21, P < or = .0007). In this sample, a significantly lower ABOI score was found for patients treated by OS compared with patients treated by GP.

Adolescent↗
PubMed2004

Use of digital photography in the Case orthodontic clinic.

In 2002, the orthodontic clinic at Case Western Reserve University totally converted to digital photography. We want to share the learning curve during this transition with clinicians planning the same change. A system and a protocol were developed for this transition; they have been in use for over a year. This system allows the handling of digital cameras when there are more clinicians than cameras; it can be applied to various specialties or fields.

Equipment Design↗
PubMed2004

Orthodontic care in suburban Cuyahoga County, Ohio: who provides treatment and whom do they treat?

It has been reported that orthodontic services are being provided to a larger segment of the population by an increasing number of providers. The present study surveyed the dental and orthodontic experiences of 10th grade students attending 16 public and two parochial high schools in suburban Cuyahoga County, Ohio, as well as two schools from the city of Cleveland. Questionnaires were distributed in the classroom and data obtained for 2808 students. Approximately 50% of the sample were girls with an average age of 15.5 +/- 0.8 years. Results of the survey revealed that 84% (2371/2808) had seen a dentist within the past year, and 37% (1047/2808) of the students had received orthodontic treatment from 171 different providers. Of those treated, 87.2% (913/1047) were treated by a specialist in orthodontics, 10.8% (114/1047) by a general dentist, and 0.7% (7/1047) by a pediatric dentist, with 1.3% missing or unknown (13/1047). Patients who had seen a dentist within the past year were more likely to have had orthodontic treatment. Only 7% of the untreated students were told by a dental professional that they needed braces compared with 71% of the treated group. Therefore, we conclude that orthodontic specialists provide most of the orthodontic services in the suburbs of Cuyahoga County, and visiting a general dentist positively influences the utilization of orthodontic services.

Adolescent↗
PubMed2004

Taking stock: assessing the present-planning the future 'you don't need a weatherman to know which way the wind blows'.

In the past, the dual nature of orthodontics has presented practitioners with unique artistic challenges and scientific opportunities. As a result, orthodontists today are enjoying the 'Platinum Age of Productivity.' However, a disturbing trend that promotes neither art nor science has emerged. Health care reform in the United States has transformed health care from a service to a commodity. Some orthodontists and orthodontic practice management companies have capitalized on this change in thinking and are aggressively promoting orthodontic treatment as a product. This paper examines the impact of this paradigm shift on the future of orthodontics. Particular attention is paid to the interaction of three themes: first, orthodontics as a product, secondly, the current misconception that there is a shortage of orthodontic practitioners in the United States, and thirdly, the difficulty in defining 'excellence' in specialty training in orthodontics. In the near future, the collision of these three concepts will result in an orthodontic 'Perfect Storm'. The ability of our specialty to survive and thrive will be proportional to our professional behavior during these difficult times...caveat emptor.

Accreditation↗
PubMed2003

Familial correlations and heritability of maxillary midline diastema.

The purpose of the study was to estimate familial correlations and heritability to evaluate familial aggregation patterns of maxillary midline diastemas. The sample consisted of 30 extended families: 15 black, 14 white, and 1 mixed race. A single ascertainment scheme was adopted to collect the sample. Family data were collected with a 7-question survey. In all, the sample of 430 subjects consisted of 220 females, 210 males, 99 nuclear families, 534 sibling pairs, 422 avuncular pairs, 318 grandparent pairs, and 27 cousin pairs. Families were stratified by race to avoid any bias. The mixed-race family was excluded from the analysis. Data were analyzed using the program REGC in the Statistical Analysis for Genetic Epidemiology (S.A.G.E., Case Western Reserve University, Cleveland, Ohio) software. Heritability was found to be 0.32 +/- 0.14 in the white sample and 0.04 +/- 0.16 in the black sample. The preliminary results suggest a possible genetic basis for maxillary midline diastema and a greater role of environmental factors in the black sample than in the white sample.

Adolescent↗