Masoud et al cross-sectionally demonstrated the relationship between blood-spot IGF-1 levels and traditional radiographic techniques of determining skeletal maturity (cervical vertebrae, hand-wrist radiographs). Moreover, studies have shown that this form of testing provides results that accurately reflect serum IGF-1 levels. The process involves a small finger prick identical to what would be necessary for a blood-sugar test. More recently, blood-spot IGF-1 testing has been used as an alternative to traditional serum testing, since it provides greater patient comfort and easier handling, and can be performed by the patient at home and sent to a laboratory. In-vivo and in-vitro studies have also demonstrated the sensitivity of mandibular condylar growth to changes in IGF-1 levels.īecause growth hormone levels fluctuate throughout the day, IGF-1 is often used in the medical profession to diagnose growth hormone disturbances and assess their severity and response to treatment. Before puberty, IGF-1 levels depend on growth hormone levels, but, with the onset of puberty, their production can also be directly stimulated by androgens such as testosterone. Insulin-like growth factor 1 (IGF-1) is a growth hormone-dependent peptide that locally and systemically stimulates growth. In addition to the potential harm from radiographic exposure, these techniques cannot determine the intensity of the mandibular growth spurt in a particular patient. Because of the radiographic nature of these techniques, they often cannot be performed more than once a year. Several studies have shown that the treatment of skeletal Class II patients with functional appliances is more successful when initiated during the adolescent growth spurt.
Traditionally, evaluations of hand-wrist radiographs and cervical vertebrae have been used to predict the timing of the mandibular growth spurt to either take advantage of it or plan to start treatment before or after it. Successful treatment of many orthodontic problems depends to a great extent on the amount of mandibular growth patients experience during treatment. The relationship between IGF-1 levels and mandibular growth after the pubertal growth spurt is not fully understood. More research is necessary to validate these results in a different population by using more advanced imaging tools and a larger sample size.
Conclusionsīlood-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. 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). The ascending group had a moderate to high correlation between average IGF-1 levels and the amount of mandibular growth for each observation period. 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). 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). Annual mandibular growth was related to changes in blood-spot IGF-1 levels over each observation period.
A total of 43 annual time intervals were gathered (17 female, 26 male). The patients’ follow-up periods ranged between 1 and 5 years. Twenty-five patients (12 female, 13 male) from an orthodontic population were longitudinally evaluated for annual IGF-1 level, cervical stage, and mandibular length. This was done by measuring annual changes in mandibular length and studying how they relate to blood-spot IGF-1 measurements and cervical stages.
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.