Morphological attributes of the logarithmic growth of the human face: gnomonic growth

Presurgical Reduction of the Cleft Palate: Serendipitous Benefit of the Stanford Orthodontic Airway Plate Treatment (SOAP) for Infants with Robin Sequence

OBJECTIVE

Narrowing of the palatal cleft is often observed in infants with Robin sequence (RS) treated with the Stanford Orthodontic Airway Plate treatment (SOAP) even though SOAP is utilized primarily to establish airway patency. The current study quantified dimensional changes of the cleft palate (CP) in infants with RS treated with SOAP.

DESIGN

A retrospective chart review.

PATIENTS

Infants with RS and CP who completed SOAP and had maxillary arch models at both pre- and post-treatment time points at a single tertiary referral hospital between September 2019 and July 2023.

SETTING AND OUTCOME MEASURE

Maxillary arch models were measured and analyzed using Bivariate statistical analysis.

RESULTS

Seventeen infants were included in the study. The median age (min, max) was 6.7 weeks (1.1, 21.9) at pre-treatment and 26.6 weeks (18.7, 37.0) at post-treatment. The median Obstructive Apnea Hypopnea Index was 36.2 events/hour (8.1, 103.1) at pre-treatment and 4.1 events/hour (1.9, 8.6) at post-treatment. The pre-treatment width of CP decreased by an average (± standard diviation) of 6.37 mm (± 3.55, p < 0.001) at post-treatment. The ratio of the posterior cleft width to the total maxillary arch width decreased from 40% (± 9.1) at pre-treatment to 22% (± 11) at post-treatment (p < 0.001).

CONCLUSION

The dimensions of CP reduced significantly during SOAP in infants with RS and CP treated for their severe upper airway obstruction. The findings highlight a potential benefit of SOAP that may contribute favorably to the palate repair surgery.

Treatment of maxillomandibular deformities with internal curvilinear distraction

Internal curvilinear distraction is successful in achieving clinically significant distraction with stable occlusion in our patient population of infants, adolescents, and adults. When distracting the mandible, the curve of the distractor, the position of the distractor, and the osteotomy site are accountable for the final result. The curved distractor can mimic part of the natural logarithmic growth of the maxillomandibular complex. In addition, the result is predictable based on this design and the internal nature of the distractor, which can be left in place longer than other distractor types. Distraction can be combined with orthognathic surgery in certain cases resulting in increased benefit. This new procedure is called distraction orthognathics.

Quantitation of maxillary remodeling. 1. A description of osseous changes relative to superimposition on metallic implants

Lateral skull radiographs for a set of 31 human subjects were examined using computer-aided methods in an attempt to quantify modal trends of maxillary remodeling during the mixed dentition and adolescent growth periods. Cumulative changes in position of anterior nasal spine (ANS), posterior nasal spine (PNS), and Point A are reported at annual intervals relative to superimposition on previously placed maxillary metallic implants. This in vivo longitudinal study confirms at a high level of confidence earlier findings by Enlow, Björk, Melsen, and others to the effect that the superior surface of the maxilla remodels downward during the period of growth and development being investigated. However, the inter-individual variability is relatively large, the mean magnitudes of change are relatively small, and the rate of change appears to diminish by 13.5 years. For the 19 subjects for whom data were available for the time interval from 8.5 to 15.5 years, mean downward remodeling at PNS was 2.50 mm with a standard deviation of 2.23 mm. At ANS, corresponding mean value was 1.56 mm with a standard deviation of 2.92 mm. Mean rotation of the ANS-PNS line relative to the implant line was 1.1 degree in the "forward" direction. However, this rotational change was particularly variable with a standard deviation of 4.6 degrees and a range of 11.3 degrees "forward" to 6.7 degrees "backward." The study provides strong evidence that the palate elongates anteroposteriorly mainly by the backward remodeling of structures located posterior to the region in which the implants were placed. There is also evidence that supports the idea of modal resorptive remodeling at ANS and PNS, but here the data are somewhat more equivocal. It appears likely, but not certain, that there are real differences in the modal patterns of remodeling between treated and untreated subjects. Because of problems associated with overfragmentation of the sample, sex differences were not investigated.

Influence of excision of the facial and inferior dental nerves on mandibular growth and development

The purpose of this study was to evaluate the role of the facial and inferior dental nerves on mandibular growth and development. A sample of 10 mongrel dogs was randomly divided into two equal groups. Avulsion of the right inferior dental nerve was carried out on the first group. Surgical cutting of the extracranial portion of the right facial nerve was performed on the second group. Sham operations were made for the left sides of the mandibles of all animals. The animals were killed 3 months later and their mandibles visually and radiographically examined. Measurements were recorded in a double-blind experimental design. The data were statistically analyzed. The results obtained from this study indicate that surgical cutting of the extracranial portion of the facial nerve resulted in unilateral facial paralysis of the muscles of expression. However, after the animals were killed, no significant statistical differences were found between the nerve-devoid and sham sides of the mandible for both the facial nerve group and the inferior dental nerve group. Nevertheless, for the inferior dental nerve group, visual and radiographic examinations revealed various morphologic differences at the angular process regions of the mandibles. The impact of neural deprivation on mandibular growth and development was thus determined.

Principal components of craniofacial growth for white Philadelphia males and females between 6 and 22 years of age

Three principal components, explaining 83 percent of the common variation for 999 males and females between 6 and 22 years of age, describe ontogenetic patterns of relationship for seven facial dimensions, including sella-nasion, sella-basion, nasion-prosthion, infradentale-menton, articulare-gnathion, gonion-gnathion, and articulare-gonion. Accounting for 65 percent of the variation, a general component associated with both size and shape defines size-required changes in proprotion during growth. Independent patterns of regional variation associated with alveolar remodeling (second component) and condylar growth (third component) describe specific sources of facial modification. Mean multivariate component scores reveal that sexual dimorphism, which progressively favors males over females with age, results from accumulating differences in size and related proportional changes in shape. The timing of the condylar growth spurt, as evident from variation in ramus height, produces secondary dimorphism which diminishes following the adolescent phase in males. Significant age effects are indicated for alveolar remodeling and mandibular growth of the condyle.

Relationships among ontogenetic, static, and evolutionary allometry

The relationship between ontogenetic, static, and evolutionary levels of allometry is investigated. Extrapolation from relative size relationships in adults to relative growth in ontogeny depends on the variability of slopes and intercepts of ontogenetic vectors relative to variability in length of the vector. If variability in slopes and intercepts is low relative to variability in length, ontogenetic and static allometries will be similar. The similarity of ontogenetic and static allometries was tested by comparing the first principal component, or size vector, for correlations among 48 cranial traits in a cross-sectional ontogenetic sample of rhesus macaques from Cayo Santiago with a static sample from which all age- and sex-related variation had been removed. The vector correlation between the components is high but significantly less than one while two of three allometric patterns apparent in the ontogenetic component are not discernable in the static component. This indicates that there are important differences in size and shape relationships among adults and within ontogenies. Extrapolation from intra-or interspecific phenotypic allometry to evolutionary allometry is shown to depend on the similarity of genetic and phenotypic allometry patterns. Similarity of patterns was tested by comparing the first principal components of the phenotypic, genetic, and environmental correlation matrices calculated using standard quantitative genetic methods. The patterns of phenotypic, genetic, and environmental allometry are dissimilar; only the environmental allometries show ontogenetic allometric patterns. This indicates that phenotypic allometry may not be an accurate guide to patterns of evolutionary change in size and shape.

Treatment of anterior skeletal open-bite deformity

Two patients with severe skeletal anterior open-bite have been presented. Treatment of these patients was accomplished mainly by mandibular repositioning (Case 1 by orthodontic means and Case 2 by a combination of surgery and orthodontics) and by an orthodontic change in the mandibular occlusal plane. A review and a discussion of the cause of this deformity were presented.

Arcial growth with metallic implants in mandibular growth prediction

The present investigation was undertaken to determine whether the Ricketts theory of arcial growth of the mandible can be put to practical use by the clinician to predict mandibular morphology. Eight subjects (six girls and two boys) were selected from the earliest implant samples at the Orthodontic Department of Emory University School of Dentistry. The initial cephalograms were coded and sent to Ricketts, and a 6-year manual growth forecast using the arcial method was requested. The final cephalograms were traced and compared. The three tracings (initial, prediction, and final) were superimposed over the metallic implants and presented on a case-by-case basis. The forecasts, in form, were clinically acceptable in five of the eight cases. In two of the cases (girls) (Cases 2 and 4) a hand-wrist radiograph to determine skeletal age would have improved their accuracy. The forecast in Case 2 was not acceptable. In view of our results in this small sample, the arcial method appears valid for prediction of amndibular growth; however, hand-wrist radiographs will improve the accuracy of short-range predictions of the amount of growth expected. For this reason, the orthodontist should constantly monitor his patients, watching for each individual to assert himself.

The allometric growth of the skull. General mode and prediction of facial growth

Analysis of skull growth in three dimensions indicates that the process is precise and ordered. It can be logarithmically represented as an expansive process taking place in straight lines. This permits prediction of future shape by forward projection of lines derived from at least two records taken at an early age. Although these longitudinal studies have been carried out in animals, the similarity between human and animal cross-sectional material suggests that the mode of growth of the human skull follows the same principles. It should be possible, with the development of more accurate recording techniques suitable for analysis in three dimensions, to project the future shape of the human skull with a substantial degree of accuracy.