Roberto Carrillo

Accuracy and reliability of tooth and root lengths measured on cone-beam computed tomographs.

INTRODUCTION In this study, we evaluated the accuracy and reliability of tooth-length and root-length measurements derived from cone-beam computed tomography (CBCT) volumetric data. METHODS CBCT scans were made of 7 fresh porcine heads. The scans were made with an i-CAT machine (Imaging Sciences International, Hatfield, Pa) at 0.2, 0.3, and 0.4 mm voxel sizes. Two film-acquired periapical radiographs were also taken of selected incisors and premolars, 52 of which (28 premolars, 24 incisors) were included in this study. By using Dolphin imaging software (version 10.5, Dolphin Imaging Systems, Chatsworth, Calif), the CBCT scans were oriented twice for each tooth (ie, 2 trials) using the mesial, distal, labial, and lingual cementoenamel junctions as reference points. Root and tooth lengths were derived from these points and compared with actual measurements of the teeth made with digital calipers after all surrounding bone had been carefully removed. RESULTS CBCT tooth-length and root-length measurements were not significantly different from the actual lengths; the mean differences were less than 0.3 mm. The periapical measurements significantly (P = 0.001) underestimated root lengths (mean difference, 2.58 mm) and overestimated tooth lengths (mean difference, 2.58 mm; P = 0.056). Mean differences between the 3 CBCT voxel sizes were all less than 0.25 mm. Within-trial method errors were almost 2 times greater for the periapical radiographs than for the CBCT scans. Between-trial method errors were greatest for the 0.4-mm CBCT scans, which were within 0.1 mm of the periapical radiograph method errors. The intraclass correlations for the periapical and CBCT measurements were all above 0.995. CONCLUSIONS CBCT scans are at least as accurate and reliable as periapical radiographs for tooth-length and root-length determinations.

Healing of the roots and surrounding structures after intentional damage with miniscrew implants

INTRODUCTION In this study, we evaluated the healing potential of the roots and surrounding periodontium (cementum, periodontal ligament [PDL], and bone) after intentional damage during miniscrew implant (MSI) placement. METHODS A randomized split-mouth design was used to evaluate healing 6 and 12 weeks after intentional root damage. Seven skeletally mature male beagle dogs had MSIs placed into the roots of 8 mandibular teeth (6 premolars, 2 first molars). After root contact had been verified by using insertion torques and radiographs, the MSIs were immediately removed, and the sites were allowed to heal for 6 or 12 weeks. Sequential point labeling was performed at 6-week intervals with tetracycline and calcein. Demineralized and undemineralized sections were stained, and healing was histologically evaluated. RESULTS The placement torque was twice as high with root contact than without contact (23.8 vs 50.7 Ncm). Damage to the roots and periodontium ranged from cementum interruption to pulp invasion. New bone, PDL, and cementum were observed in 64.3% of the teeth, with significant (P <0.05) increases in the percentages of cementum over time. Sequential labeling confirmed healing at both 6 and 12 weeks. Abnormal healing was found in 35.7% of teeth; it included lack of PDL and bone regeneration, bone degeneration in the furcation area, ankylosis, and no healing associated with inflammatory infiltrate or pulpal invasion. CONCLUSIONS Under favorable conditions (no inflammatory infiltrate or pulpal invasion), healing can occur when root damage caused by MSIs is limited to the cementum or the dentin. Increased resistance should be used as an indicator of possible root contact during MSI placement.

Effects of intentional damage of the roots and surrounding structures with miniscrew implants

INTRODUCTION The purposes of the study were to evaluate the immediate damage to roots and periodontal structures after initial miniscrew implant (MSI) placement and the short- and long-term damage after MSIs were left in situ. METHODS The roots of the maxillary second, third, and fourth premolars of 7 mature beagle dogs were randomly assigned to undergo immediate, short-term (left for 6 weeks), or long-term (left for 12 weeks) damage. Intentional damage was inflicted with self-tapping screws (1.8 x 8 mm) placed with a stent. Alternating tetracycline and calcein labels were administered at 6-week intervals. Undecalcified sections were stained and evaluated histologically to determine the extent of damage; healing was evaluated by using fluorescence labels. RESULTS Histology showed damage to 73.8% of the teeth, ranging from displacement of bone into the periodontal ligament to invasion of the pulp chamber. Displacement of bone into the periodontal ligament and direct damage to the periodontal ligament occurred in 3 (7.2%) instances. Damage was isolated to the cementum of 8 (19.0%) teeth, whereas damage occurred in the dentin of 11 (26.2%) teeth. Loss of bone in the furcation was evident in 3 (7.2%) teeth, and severe damage into the pulp occurred in 6 (14.2%) teeth. No differences in the amounts of damage were evident between the immediate, short-, and long-term groups. Healing often occurred with cementum around the unloaded MSIs. CONCLUSIONS Extensive damage can be caused by MSIs, with little to no differences evident over time. Unloaded MSIs that remain in contact with roots of teeth can show varying degrees of healing.

Orthopedic Correction of Growing Hyperdivergent, Retrognathic, Patients with Miniscrew Implants

Traditional orthodontic treatments do not adequately address the skeletal problems of retrognathic, hyperdivergent, Class II adolescents; the few approaches that do address them require long-term patient compliance. This article introduces a novel approach using miniscrew implants (MSIs) and growth to treat retrognathic, hyperdivergent adolescents. Nine consecutive patients were evaluated at the start of treatment (aged 13.2 ± 1.1 years) and again at the end of the orthopedic phase (after 1.9 ± 0.3 years). Each patient had 2 MSIs placed in either side of the palate. Coil springs (150 g) extended from the MSIs to a rapid palatal expander, which served as a rigid segment for intruding the maxillary premolar and molars. Two additional MSIs were placed between the first mandibular molars and second premolars; coil spring (150 g) extended from the MSIs to hold or intrude the mandibular molars. Before treatment, the patients exhibited substantial and significant mandibular retrusion (Z score = -1.0), facial convexity (Z score = 0.7), and hyperdivergence (Z score = 1.6). Treatment produced consistent and substantial orthopedic effects. The chin was advanced by a mean of 2.4 mm, the sella-nasion-basion (SNB) angle increased by 2.1°, the mandibular plane angle decreased by 3.9°, and facial convexity decreased by approximately 3.2°. Questionnaires showed that this treatment approach was not painful or uncomfortable; the majority of the patients indicated that they were very likely to recommend the treatment to others. Treatment was accomplished by titrating the amount of orthodontic intrusion performed based on the individuals growth potential.

Maxillary and mandibular dentoalveolar heights of French-Canadians 10 to 15 years of age.

OBJECTIVE To establish reference data for anterior and posterior dentoalveolar heights of growing French-Canadians with untreated normal occlusions and malocclusions. MATERIALS AND METHODS The mixed longitudinal sample includes 227 French-Canadians, 119 male and 108 female, with cephalograms taken annually between 10-15 years of age. Maxillary and mandibular dentoalveolar heights were measured as the perpendicular distances of the incisor tips and first molar mesial cusp tips to the palatal (ANS-PNS) and mandibular (Go-Me) planes. RESULTS Male dentoalveolar heights were significantly (P < .05) greater than female heights at all ages. Dentoalveolar heights at 15 years of age were significantly larger (P < .05) than at 10 years of age, with differences ranging from 2.1-4.2 mm in male subjects and from 2.1-3.8 mm in female subjects. The greatest difference in dentoalveolar heights between the 10- and 15-year-old age groups was for the maxillary first molar; the maxillary central incisor height showed the smallest age effects. The coefficients of variation were greater for the maxillary than the mandibular dentoalveolar heights. Correlations of dentoalveolar heights within jaws ranged from 0.53 to 0.82; correlations between jaws ranged from 0.30 to 0.44. The mandibular heights showed the strongest associations. CONCLUSIONS French-Canadian adolescents require age- and sex-specific reference data for dentoalveolar heights.

Histologic evaluation of root response to intrusion in mandibular teeth in beagle dogs

INTRODUCTION The purpose of this article was to histologically evaluate root resorption and repair after orthodontic intrusion with different force magnitudes and fixed anchorage. METHODS A randomized split-mouth repeated-measure design was used. Intrusive forces were applied for 98 days to the mandibular second, third, and fourth premolars of 8 mature beagle dogs. Two miniscrew implants were used as anchorage to apply constant intrusive forces of 50, 100, or 200 g per tooth. Demineralized sections of each tooth were stained and histologically studied for root resorption. Multilevel statistical procedures were used to evaluate the results. RESULTS Root resorption was present in all teeth, independent of the force applied. Significant differences were found between root regions, with the apices and the interradicular regions the most affected and with dentin involvement at the furcation. There was cementum repair in 24.14% of the lacunae. Light constant intrusive forces between 50 and 200 g showed no significant differences in the amount of resorption produced. Resorption was more frequently seen at the level of the apices and the furcation. CONCLUSIONS Orthodontically induced root resorption is not clinically significant after application of continuous intrusive forces between 50 and 200 g. Moreover, there is no relationship between root resorption, the position of posterior mandibular teeth in the arch, and the amount of intrusive force applied.

Rhinitis, sinusitis and ocular disease – 2097. Dentomaxilofacial disorders in children with allergic rhinitis

Children with allergic rhinitis were phenotypically characterized by rings (92%, p= 0.03), vertical facial plane growth (25%, p = 0.016), nasal fold (78%, p = 0.00) and retrognathia (17%, p = 0.057). In risk analysis found that mouth breathing increased 47.5 times the risk of allergic rhinitis. Children with persistent rhinitis and asthma had more mouth breading, snoring and jaw compression than children only with rhinitis. Conclusions Children with allergic rhinitis had higher prevalence of facial, tooth and jaw disorders than children without rhinitis. We recommend a multidisciplinary assessment to identify dentomaxilofacial alterations in this high risk groups and provide early treatment.

Orthodontic treatment for a patient with congenital cutis laxa.

This case report was shown at the student case display, sponsored by the College of Diplomates of the American Board of Orthodontics at the 2006 AAO Annual Session.