Enhancement of orthodontic anchorage and retention by the local injection of strontium: an experimental study in rats

To examine the clinical and histological effects of locally injected strontium on the anchoring unit of a rat model of an experimental relapsed tooth movement. Thirty-six 10-week-old male Wister rats were randomly divided into two groups of 18 animals that were then randomly divided into three subgroups of six animals corresponding to three observation periods: T1 = 1 week, T2 = 2 weeks, and T3 = 3 weeks. In the first experiment, both the right and left maxillary first molars were moved buccally with a standardized expansive spring. Strontium chloride solution was injected every 2 days into the subperiosteal area buccal to the left maxillary first molar [the experimental side]. The right-sided first molar was injected with distilled water as a control. In the second experiment, maxillary first molars were moved buccally with the spring. After 3 weeks, the spring was removed. Two days before the spring removal, strontium chloride was injected into the palatal side of left-sided maxillary first molar and distilled water was injected into the palatal side of the right-sided maxillary first molar as in experiment 1. At the end of the experimental period, significant levels of inhibition were noted in terms of both tooth movement and relapse movement in strontium-injected sides. Histological examinations showed that strontium enhanced the number of osteoblasts and reduced the number of osteoclasts. The local injection of strontium can inhibit the degree of experimental and relapsed tooth movement in a rat model

Assessment of mandibular asymmetry

This study was done to assess mandibular asymmetry as a dentofacial deformity in patients with clinically evident mandibular asymmetry. The sample consisted of 33 Iraqi patients with different mandibular asymmetry conditions selected from different hospitals in Baghdad and Mosul. Comprehensive examination protocol was established for each patient and the deformity of mandibular asymmetry had been classified into six different conditions. The study shows that cases with unilateral overgrowth, asymmetric mandibular enlargement, constitute 81.8% of the sample, while cases with unilateral undergrowth, asymmetric mandibular deficiency, constitute 18.2% only. Mandibular asymmetry is not a rare dentofacial deformity and it can be due to unilateral overgrowth; asymmetric mandibular enlargement; or unilateral undergrowth; asymmetric mandibular deficiency

Dental maturity and chronological age in a sample of growth hormone deficient patients aged 4-16 years

In the past few decades, the availability of much improved endocrine assay techniques has focused attention upon hormones as major determinants of human growth and development. This cross-sectional study aimed to explore the direct effect of Growth Hormone Deficiency [GHD] on the rate of dental development that might indirectly affect the classical orthodontic treatment timing standards. Additionally, the magnitude of any possible differential effect of this endocrinopathy on the somatic and dental systems development has to be searched. The sample consisted of 87 patients suffering of isolated GHD aged 4-16 years with a comparable control group of normally growing Iraqi subjects. The results declared a highly significant retardation in the rate of dental development of the GHD patients, with a total mean delay of 1.5 years. The dental age delay of the youngest GHD children [4- 5 years] was minimal [tilde 0.6 years], meanwhile the maximal delay [tilde 1.8 years] was recorded about the pre-pubertal growth phase [9-12 years]. At the same time, there was an obvious differential effect of GHD on the height age and dental age, in which a greater retardation was always imposed on the somatic maturity indicator compared to the dental one, a finding that might be attributed to the different developmental patterns and embryonic origins of teeth and bones

Relapse during retention with Hawley and clear overlay retainers in Iraqi adults

Maintaining the treatment results following orthodontic treatment is one of the most important aspects of the entire orthodontic treatment process. The purpose of the present study was to evaluate and compare the uses of Hawley and clear overlay orthodontic retainers relative to changes in overjet, overbite, intermolar width, intercanine width, and arch length measurements. These measurements were quantified in 48 adult patients at the time of insertion and after three months. The patients had pretreatment class I or class II div I relationship and were treated with preadjusted fixed appliance. Cases with open bite or crossbite were excluded from this study. Results showed that with Hawley retainer there was a significant change in the overbite measurements, while with clear overlay retainer there was no significant change during retention. The retentive capacities of the two retainers differ as Hawley retainer allows relative vertical movement of the posterior teeth, while clear overlay retainer holds teeth in their previous debanding position