George J. Cisneros

Nickel hypersensitivity in the orthodontic patient

Nickel is one of the most common causes of allergic contact dermatitis and produces more allergic reactions than all other metals combined. Currently, several brands of orthodontic wires are made of nickel titanium alloy and potentially have a high enough nickel content to provoke manifestations of allergic reactions in the oral cavity. The objectives of this study were (1) to determine if standard orthodontic therapy can sensitize patients to nickel, and (2) to assess gingival response to nickel-containing orthodontic appliances in patients who are nickel sensitive before treatment. Nickel sensitivity patch tests were conducted to confirm hypersensitivity to nickel. Twenty-nine patients from the Division of Orthodontics, Albert Einstein/Montefiore Medical Center were tested, ranging in age from 12 to 48 years. Of the 29 patients, there were 18 female and 11 males. Five of the patients had a positive nickel patch test, a rate of 18.5%. The five patients that tested positive were all female, meaning that the overall rate for females was 27.7% (5:18). The five female patients sensitive to nickel were followed monthly by intraoral photos and gingival and plaque index scores. The remaining patients began routine orthodontic therapy and were retested 3 months into treatment to see whether sensitization occurred. Two patients converted from an initial negative patch test to a positive test. There may be a risk of sensitizing patients to nickel with long-term exposure to nickel-containing appliances as occurs in routine orthodontic therapy.

Comparison of Hyrax and bonded expansion appliances.

The majority of rapid maxillary expansion studies have reported the use of appliances with metal bands attached to the posterior teeth. Tooth extrusion, dental tipping, and an increase in the vertical dimension are often encountered, which may not coincide with treatment objectives. Bonded appliances using interocclusal acrylic may control the vertical dimension and expand the maxillary halves in a more bodily and symmetrical fashion. The purpose of this clinical trial was to determine, by radiographic analysis, the differences between a conventional banded expander (Hyrax) and a bonded acrylic expander. Fourteen patients who exhibited a need for expansion were enrolled in the study. The results suggest that the increase in the vertical dimension often seen with the more conventional Hyrax appliance may be minimized or negated with the bonded appliance. However, there appeared to be no significant difference between the amount of dental tipping or symmetrical expansion between the two appliances, as previously theorized.

Cytokine Expression and Accelerated Tooth Movement

It has been shown that inhibiting the expression of certain cytokines decreases the rate of tooth movement. Here, we hypothesized that stimulating the expression of inflammatory cytokines, through small perforations of cortical bone, increases the rate of bone remodeling and tooth movement. Forty-eight rats were divided into 4 groups: 50-cN force applied to the maxillary first molar (O), force application plus soft tissue flap (OF), force application plus flap plus 3 small perforations of the cortical plate (OFP), and a control group (C). From the 92 cytokines studied, the expression of 37 cytokines increased significantly in all experimental groups, with 21 cytokines showing the highest levels in the OFP group. After 28 days, micro-computed tomography, light and fluorescent microscopy, and immunohistochemistry demonstrated higher numbers of osteoclasts and bone remodeling activity in the OFP group, accompanied by generalized osteoporosity and increased rate of tooth movement.

Computerized skeletal scintigraphy for assessment of mandibular asymmetry.

Normal standards of technetium-99m methylene diphosphonate (99mTc-MDP) uptake in the jaws of adults and growing children have previously been established. This study utilizes the technique of skeletal scintigraphy for diagnosis and treatment planning in 21 patients with mandibular asymmetry. Diagnoses included hemifacial microsomia (n = 6), condylar hyper or hypoplasia (n = 10), and generalized mandibular asymmetry (n = 5). 99mTc-MDP uptake was measured in the right and left condyle, ramus, and body. Uptake was then compared with the known age-adjusted standards. The data were used to determine 1) mandibular growth activity, 2) normal vs. abnormal side, and 3) the effects of operative and functional therapy. The presence of end stage deformity was predicted when mandibular uptake reached the adult norm.

A cephalometric comparative study of the soft tissue airway dimensions in persons with hyperdivergent and normodivergent facial patterns

PURPOSE This study was performed to compare the dimensions of the nasopharynx, oropharnynx, and hypopharynx of persons with hyperdivergent and normodivergent facial types, and to determine whether any variations exist. PATIENTS AND METHODS Lateral cephalometric records of a population with a normodivergent facial pattern (n = 23) and a group with a hyperdivergent facial pattern (n = 27) as evidenced by increased mandibular plane angle were used to compare the soft tissue airway dimensions. Statistical analysis consisted of Students t-tests, Wilcoxon rank sums, and chi2. Statistical significance was set .05. RESULTS Overall the hyperdivergent group had a narrower anteroposterior pharyngeal dimension than the normodivergent control group. This narrowing was specifically noted in the nasopharynx at the level of the hard palate and in the oropharynx at the level of the tip of the soft palate and the mandible. In addition, the posterior pharyngeal wall had a thinning at the level of the inferior border of the third cervical vertebrae, and there was a more obtuse palatal angle. The tongue was also positioned more inferiorly and posteriorly in the hyperdivergent group, as evidenced by the increased distance between the hyoid bone and the mandibular plane and the increased distance between the soft palate tip and the epiglottis. The hyperdivergent group had more retruded maxillary and mandibular apical bases and a higher Class II skeletal discrepancy. CONCLUSIONS The narrower anteroposterior dimension of the airway in hyperdivergent patients may be attributable to skeletal features common to such patients, that is, retrusion of the maxilla and the mandible and vertical maxillary excess. Other features, such as an obtuse soft palate and low-set hyoid, also may be contributory factors. The relatively thin posterior pharyngeal wall observed in hyperdivergent patients might be a compensatory mechanism.

Collagen XI sequence variations in nonsyndromic cleft palate, Robin sequence and micrognathia

Cleft palate is a common birth defect, but its etiopathogenesis is mostly unknown. Several studies have shown that cleft palate has a strong genetic component. Robin sequence consists of three of the following four findings: micrognathia, glossoptosis, obstructive apnea, and cleft palate. While cleft palate is mainly nonsyndromic, about 80 percent of Robin sequence cases are associated with syndromes. Mutations in genes coding for cartilage collagens II and XI, COL2A1, COL11A1 and COL11A2, have been shown to cause chondrodysplasias that are commonly associated with Robin sequence, micrognathia or cleft palate. We therefore analyzed a cohort of 24 patients with nonsyndromic Robin sequence, 17 with nonsyndromic cleft palate and 21 with nonsyndromic micrognathia for mutations in COL11A2. A total of 23 Robin sequence patients were also analyzed for mutations in COL2A1 and COL11A1. We detected two disease-associated mutations in patients with Robin sequence, an Arg to stop codon mutation in COL11A2 and a splicing mutation in COL11A1. Two putatively disease-associated sequence variations were found in COL11A1 in Robin sequence patients, one in COL11A2 in a patient with micrognathia and one in COL2A1 in two patients with Robin sequence. The results showed that sequence variations in these genes can play a role in the etiology of Robin sequence, cleft palate and micrognathia but are not common causes of these phenotypes.

The effect of acetaminophen on tooth movement in rabbits

Orthodontic patients have reported the use of analgesics during therapy. However, common anti-inflammatory analgesics, such as aspirin and ibuprofen, have been shown to slow the rate of tooth movement. Acetaminophen, another common analgesic, does not possess anti-inflammatory properties. The effect of acetaminophen on tooth movement was studied using New Zealand white rabbits. Experimental animals were matched to a control animal of the same sex and weight. Under anesthesia, springs were ligated between the lower first molar and incisor, resulting in approximation of these teeth. Under blinded conditions, seven of the rabbits received 1000 mgs of acetaminophen daily. Seven control animals received water. The animals were sacrificed after 21 days. The movement of incisors and molars was measured. Results showed considerable movement within both the experimental and control groups, but no significant difference in tooth movement between them. Acetaminophen has no effect on the rate of tooth movement in rabbits undergoing orthodontic treatment.

Assessment of mandibular growth by skeletal scintigraphy

Accurate assessment of facial skeletal growth remains a major problem in craniomaxillofacial surgery. Current methods include 1) comparisons of chronologic age with growth histories of the patient and the family, 2) hand-wrist radiographs compared with a standard, and 3) serial cephalometric radiographs. Uptake of technetium-99m methylene diphosphonate into bone is a reflection of current metabolic activity and blood flow. Therefore, scintigraphy with this radiopharmaceutical might serve as a good method of assessing skeletal growth. Thirty-four patients, ranging in age from 15 months to 22 years, who were undergoing skeletal scintigrams for acute pathologic conditions of the extremities, were used to develop standards of uptake based on age and skeletal maturation. The results indicate that skeletal scintigraphy may be useful in evaluation of mandibular growth.

Periodontal status of adult patients treated with fixed buccal appliances and removable aligners over one year of active orthodontic therapy

OBJECTIVE To compare the periodontal status of adults treated with fixed buccal orthodontic appliances vs removable orthodontic aligners over 1 year of active therapy. MATERIALS AND METHODS The study population consisted of 42 subjects; 22 treated with fixed buccal orthodontic appliances and 20 treated with removable aligners. Clinical indices recorded included: plaque index (PI), gingival index (GI), bleeding on probing (BOP), and probing pocket depth (PPD). Plaque samples were assessed for hydrolysis of N-benzoyl-DL-arginine-naphthylamide (BANA test). Indices and BANA scores were recorded before treatment and at 6 weeks, 6 months, and 12 months after initiation of orthodontic therapy. RESULTS After 6 weeks, only mean PPD was greater in the fixed buccal orthodontic appliance group. However, after 6 months, the fixed buccal orthodontic appliance group had significantly greater mean PI, PPD, and GI scores and was 5.739 times more likely to have a higher BANA score. After 12 months, the fixed buccal orthodontic appliance group continued to have greater mean PI, GI, and PPD, while a trend was noted for higher BANA scores and BOP. CONCLUSIONS These results suggest treatment with fixed buccal orthodontic appliances is associated with decreased periodontal status and increased levels of periodontopathic bacteria when compared to treatment with removable aligners over the 12-month study duration.

Comparison of the Craniofacial Characteristics of Two Syndromes Associated with the Pierre Robin Sequence

The craniofacial characteristics of two syndromes commonly associated with Robin sequence were compared for 49 subjects. Lateral cephalograms were analyzed for four groupings: Group I--Stickler syndrome with versus without Robin, Group II--velocardiofacial (VCF) syndrome with versus without Robin, Group III--Stickler without Robin compared to VCF without Robin, and Group IV--Stickler with Robin compared to VCF with Robin. Thirty-two skeletal and 18 soft tissue measurements were compared. In Group I, three skeletal measurements were significantly different (SNA, SNB, and SNPg). In Group II, no significant difference was found for any of the 50 measurements. In Group III, a significant difference was demonstrated for seven parameters (one skeletal, six pharyngeal and airway). In Group IV, two skeletal and eight airway measures were significantly different. The findings indicate that the relative maxillary and mandibular retrognathia observed in Stickler/Robin patients may predispose them to the Robin sequence and vice versa; the Robin features in VCF may be caused by hypotonia rather than any craniofacial or physical obstruction of the airway; Stickler and VCF are similar in craniofacial morphology but show marked differences in pharyngeal and airway morphology; and cephalometrics should not be the sole prognosticator of the Robin sequence and its association with Stickler and VCF.