Are mutations in parathyroid hormone receptor linked to undererupted molars associated with osteoarthritis?
Frazier-Bowers SA, Hendricks HM, Wright JT, Lee J, Long K, Dibble CF, et al. Novel mutations in PTH1R associated with primary failure of eruption and osteoarthritis. J Dent Res 2014;93:134-9
Primary failure of eruption is a rare condition characterized by undererupted permanent molars without mechanical obstructions, estimated to occur in less than 1% of the population. Since these molars do not respond to orthodontic force, proper diagnosis is important in managing these patients. The authors and others have previously reported that loss-of-function mutations of parathyroid hormone receptor-1 gene (PTH1R) segregate with familial nonsyndromic primary failure of eruption. There are 2 ligands for this receptor: systemically circulating parathyroid hormone (PTH) and locally acting PTH -related peptide (PTHrP). PTHrP is highly expressed during tooth development, but the mechanisms of how defective PTH1R causes primary failure of eruption are unknown. PTH1R is an important gene that regulates skeletal development, and its loss-of-function and activating mutations cause various types of severe skeletal dysplasia manifested early in life. It is interesting that primary failure of eruption is the only condition that PTH1R haploinsufficiency (1 copy inactivated) is known to cause, probably because tooth development and eruption are a relatively sensitive system requiring PTH1R at a complete level. These authors implicated an intriguing association between primary failure of eruption and osteoarthritis, reporting that some of familial primary failure of eruption patients had early onset osteoarthritis. Osteoarthritis normally develops later in life, without any conspicuous defects in bone development. Whether PTH1R is relevant to osteoarthritis has not been reported. PTH1R plays critical roles in bone and cartilage development, and 1 susceptibility locus identified by a recent Genome-Wide Association Study includes PTHrP. The lesson to learn from this important study is that the mutations that we thought are relevant only to orthodontists might actually have further implications on more severe degenerative bone diseases later in life.
Reviewed by Wanida Ono
Psychological aspects of pain induced by orthodontic separators
Beck VJ, Farella M, Chandler NP, Kieser JA, Thomson WM. Factors associated with pain induced by orthodontic separators. J Oral Rehabil 2014;41:282-8
Pain from the application of orthodontic forces has always been an interesting phenomenon for orthodontists and especially to patients. These authors’ objective was to compare participants with high and low pain levels with respect to their anxiety, dental anxiety, catastrophizing, cold sensitivity, and tooth sensitivity. One hundred seventy patients were initially screened to identify those who were high and low pain responders. Participants completed 6 visual analog scales of pain after having 2 elastomeric separators placed between the mandibular right first molars over 48 hours. A total of 20 participants (10 with high pain, 10 with low pain) were selected for the testing phase to assess anxiety levels, dental fear, sensitivity of teeth, general sensitivity, and dental pain thresholds with the dental anxiety scale, pain catastrophizing scale, Spielberger’s state trait anxiety inventory, cold pressor test, and electrical pulp test, respectively. Peak pain on the visual analog scale occurred during the second evening of the 48-hour period. Statistically significant differences were found between the high and low pain responders across all 3 categories by using the pain catastrophizing scale. Multivariate analysis showed for every pain catastrophizing scale magnification score of 1 unit higher, the relative risk of being a high pain responder was 1.6 ( P = 0.002). The dental anxiety scale scores of high pain responders were twice as high, and they experienced more pain than did the low pain responders based on these scores and the first 2 minutes of the cold pressor test, respectively. The findings from this study demonstrated that the pain perceived after orthodontic force application is strongly related to psychological characteristics. Orthodontists must continue to stress the importance of light continuous forces to alleviate our patients’ misconceptions from the days when orthodontic visits meant “tightening teeth” with heavy steel wires.
Reviewed by Rishi Popat
Psychological aspects of pain induced by orthodontic separators
Beck VJ, Farella M, Chandler NP, Kieser JA, Thomson WM. Factors associated with pain induced by orthodontic separators. J Oral Rehabil 2014;41:282-8
Pain from the application of orthodontic forces has always been an interesting phenomenon for orthodontists and especially to patients. These authors’ objective was to compare participants with high and low pain levels with respect to their anxiety, dental anxiety, catastrophizing, cold sensitivity, and tooth sensitivity. One hundred seventy patients were initially screened to identify those who were high and low pain responders. Participants completed 6 visual analog scales of pain after having 2 elastomeric separators placed between the mandibular right first molars over 48 hours. A total of 20 participants (10 with high pain, 10 with low pain) were selected for the testing phase to assess anxiety levels, dental fear, sensitivity of teeth, general sensitivity, and dental pain thresholds with the dental anxiety scale, pain catastrophizing scale, Spielberger’s state trait anxiety inventory, cold pressor test, and electrical pulp test, respectively. Peak pain on the visual analog scale occurred during the second evening of the 48-hour period. Statistically significant differences were found between the high and low pain responders across all 3 categories by using the pain catastrophizing scale. Multivariate analysis showed for every pain catastrophizing scale magnification score of 1 unit higher, the relative risk of being a high pain responder was 1.6 ( P = 0.002). The dental anxiety scale scores of high pain responders were twice as high, and they experienced more pain than did the low pain responders based on these scores and the first 2 minutes of the cold pressor test, respectively. The findings from this study demonstrated that the pain perceived after orthodontic force application is strongly related to psychological characteristics. Orthodontists must continue to stress the importance of light continuous forces to alleviate our patients’ misconceptions from the days when orthodontic visits meant “tightening teeth” with heavy steel wires.
Reviewed by Rishi Popat
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