Longitudinal relationship between insulin-like growth factor-1 levels and vertical facial growth.

BACKGROUND: Facial growth in the vertical dimension is the last to be completed and can often be detrimental to the success of dental implants, orthodontic treatment, and orthognathic surgery that young individuals undergo. AIM: The purpose of this study was to evaluate the longitudinal relationship between changes in total anterior facial height and insulin-like growth factor-1 (IGF-1) levels measured using blood-spot samples. METHODS: Our sample included 25 orthodontic patients from whom we had access to annual lateral cephalometric radiographs and IGF-1 measurements. Each subject was observed between 2 and 6 times, resulting in 43 annual intervals from a total of 77 observations. RESULTS: We noted a significant moderate positive correlation (+ 0.48) between the percentage of change in blood-spot IGF-1 levels and the percentage of change in total anterior face height (p = 0.01). CONCLUSION: Longitudinal changes in IGF-1 levels can be used to predict a patient's vertical facial growth. There was no significant correlation between changes in vertical facial development and a single cross-sectional IGF-1 measurement.

Predicting changes in mandibular length and total anterior facial height using IGF-1, cervical stage, skeletal classification, and gender.

BACKGROUND: The purpose of this study was to predict the annual growth rate of the mandible and total anterior facial height using IGF-1 levels together with cervical stage, skeletal classification, and gender. METHODS: Twenty-five orthodontic patients (12 females and 13 males) had their cervical stages, blood-spot IGF-1 levels, and cephalometric parameters measured at 1-year intervals. The number of years each patient was followed up varied between 1 and 5 years resulting in 43 12-month intervals collected from 77 observations. Descriptive, bivariate, and regression analyses were used to analyze this data. RESULTS: The linear regression model for predicting the annual mandibular growth rate was significant at p < 0.01 with an R-square value of 0.52. We found that the average IGF-1 level for the interval, the change in IGF-1 level, and the presence of a skeletal class III pattern were statistically significant predictors of mandibular growth. The regression model for predicting the annual change in anterior facial height was significant at p < 0.01 with an R-square value of 0.42. We found that the change in IGF-1 level was the only statistically significant predictor of this outcome. CONCLUSIONS: The proposed method which combines IGF-1 levels with information that is readily available to clinicians can be used to predict the timing and intensity of the growth spurt. These factors together explain more of the observed individual variation in growth rate than any of the factors used in isolation.

Prospective longitudinal evaluation of the relationship between changes in mandibular length and blood-spot IGF-1 measurements.

INTRODUCTION: The purpose of this study was to develop the use of a biologic marker, insulin-like growth factor (IGF-1), as an indicator for the timing and intensity of mandibular growth. This was done by measuring annual changes in mandibular length and studying how they relate to blood-spot IGF-1 measurements and cervical stages. METHODS: Twenty-five patients (12 female, 13 male) from an orthodontic population were longitudinally evaluated for annual IGF-1 level, cervical stage, and mandibular length. The patients' follow-up periods ranged between 1 and 5 years. A total of 43 annual time intervals were gathered (17 female, 26 male). Annual mandibular growth was related to changes in blood-spot IGF-1 levels over each observation period. RESULTS: When the whole sample was pooled into 1 group, we found a statistically significant mild to moderate correlation between the percentages of change in mandibular length and in IGF-1 levels (r = 0.4, P = 0.008). When the sample was divided based on whether the IGF-1 levels were increasing or decreasing at each yearly interval, the group with ascending IGF-1 levels had significantly more mandibular growth than did the group with descending IGF-1 levels (3.5 and 1.3 mm, respectively; P = 0.026). The ascending group had a moderate to high correlation between average IGF-1 levels and the amount of mandibular growth for each observation period. Observation periods with ascending IGF-1 levels and an average level greater than 250 µg per liter had significantly greater annual mandibular growth than did the rest of the patients with ascending IGF-1 levels (5.6 and 2.1 mm, respectively). CONCLUSIONS: Blood-spot IGF-1 testing is a promising tool for predicting the timing and the intensity of the mandibular growth spurt without the restrictions involved with radiographic techniques for assessing skeletal maturity. More research is necessary to validate these results in a different population by using more advanced imaging tools and a larger sample size. The relationship between IGF-1 levels and mandibular growth after the pubertal growth spurt is not fully understood.