Comparison of numeric techniques in the analysis of cleft palate dental arch form change

Longitudinal Craniofacial Growth Patterns in Patients with Orofacial Clefts: Geometric Morphometrics

Objective

To demonstrate craniofacial developmental patterns in repaired cleft lip and cleft palate (CLP).

Design

Retrospective, longitudinal.

Setting

Center for Craniofacial Disorders, San Juan, Puerto Rico.

Sample

Males aged 9 to 17 years: 13 noncleft (NC) Class I occlusion (NCC1); 13 NC Class III malocclusion (NCC3); 12 CLP Class I occlusion (CLPC1); and 15 CLP Class III malocclusion (CLPC3).

Main Outcome Measures

Form changes (ages 10, 13, and 16 years), using finite-element scaling analysis.

Results

NCC1, 10 to 13 interval: 30% size increase in upper midface (p < .05), mental region (p < .01), mandibular body (p < .05); 13 to 16 interval: 10% to 35% size increase in bimaxillary region and ramus (p < .01). NCC3, 10 to 13 interval: 10% to 40% size increase in posterior cranial base, upper midface, and mandible (p < .05); 13 to 16 interval: 10% to 30% size increase in bimaxillary region (p < .01), especially ramus. CLPC1, 10 to 13 interval: 10% to 15% size increase in posterior cranial base (p < .01), midface (p < .05), and mandibular ramus (p < .05); 13 to 16 interval: 8% to 20% size increase in upper midface (p < .01), lower midface (p < .05), and mandible (p < .05). CLPC3, 10 to 13 interval: no significant changes; 13 to 16 interval: upper midface and cranial base show nonsignificant size decreases, but ramus showed size increase.

Conclusions

Noncleft and CLP Class 1 occlusion groups show similar craniofacial growth patterns. Noncleft Class III groups show excessive cranial and mandibular growth. Class III malocclusion in CLP patients is associated with clinically deficient craniomaxillary growth. Growth guidance may be indicated in children with CLP with unfavorable craniofacial growth patterns.

The Measurement of Local Variation in Shape

Geometric morphometrics comprises tools for measuring and analyzing shape as captured by an entire set of landmark configurations. Many interesting questions in evolutionary, genetic, and developmental research, however, are only meaningful at a local level, where a focus on "parts" or "traits" takes priority over properties of wholes. To study variational properties of such traits, current approaches partition configurations into subsets of landmarks which are then studied separately. This approach is unable to fully capture both variational and spatial characteristics of these subsets because interpretability of shape differences is context-dependent. Landmarks omitted from a partition usually contain information about that partition's shape. We present an interpolation-based approach that can be used to model shape differences at a local, infinitesimal level as a function of information available globally. This approach belongs in a large family of methods that see shape differences as continuous "fields" spanning an entire structure, for which landmarks serve as reference parameters rather than as data. We show, via analyses of simulated and real data, how interpolation models provide a more accurate representation of regional shapes than partitioned data. A key difference of this interpolation approach from current morphometric practice is that one must assume an explicit interpolation model, which in turn implies a particular kind of behavior of the regions between landmarks. This choice presents novel methodological challenges, but also an opportunity to incorporate and test biomechanical models that have sought to explain tissue-level processes underlying the generation of morphological shape.

Comparative osseous and soft tissue morphology following cleft lip repair

OBJECTIVE

To quantify comparative improvement between osseous and soft tissue asymmetry following primary lip repair.

DESIGN

Retrospective analysis of preoperative and postoperative computed tomography scans of infants with unilateral cleft lip and palate. Sixteen soft tissue landmarks were placed using an exploratory two-/three-dimensional image processing system and compared for asymmetry.

PATIENTS

Computed tomography scans were obtained on 26 patients (13 boys, 13 girls) of Chinese ethnicity (mean age = 0.25 years) prior to Millard lip repair. Nineteen of these contributed to follow-up comparative studies prior to palatoplasty at a mean age of 0.92 years. There were 18 left-sided and eight right-sided clefts.

MAIN OUTCOME MEASURE

Euclidean distance matrix asymmetry analysis was used to determine the amount of soft tissue asymmetry pre- and postlip repair. Similar analyses of the same scans were performed for 41 osseous landmarks.

RESULTS

Soft tissue landmarks had 36/39 (92%) preoperative and 13/39 (33%) postoperative asymmetric pairs. Osseous distances demonstrated 77/125 (61%) asymmetric pairs preoperatively and 60/125 (48%) postoperatively. Soft tissue and osseous distances of the lip region demonstrated 32% and 39% postoperative asymmetry, respectively. Soft tissue and osseous distances of the nasal region demonstrated 52% and 72% postoperative asymmetry, respectively. Soft tissue and osseous distances of the facial landmarks demonstrated 24% and 34% postoperative asymmetry, respectively.

CONCLUSIONS

Primary lip repair appears to effect gains in symmetry in soft tissue and provides sufficient molding forces to cause correlating symmetry changes in underlying osseous structures.