José Nelson Mucha

Tomographic mapping of mandibular interradicular spaces for placement of orthodontic mini-implants

INTRODUCTION The purposes of this study were to determine the ideal sites for placement of orthodontic mini-implants in mandibular interradicular spaces by using computed tomography (CT) and to suggest length, diameter, and angulation of the mini-implants. METHODS CT scans were performed on 15 dry human mandibles with 1-mm tomography slices. Measurements were made at 3, 5, 7, 9, and 11 mm heights from the bone crest. Bone thickness was obtained for the buccolingual, lingual cortex, and buccal cortex areas. The mesiodistal interradicular distance and the distance from the bone crest to the mental foramen were also measured. Simulated placement of 1.5 x 9 mm mini-implants was performed in the tomographic images at angulations 10 degrees , 20 degrees , and 30 degrees . Twenty-four 1.5 x 9 mm mini-implants were then placed in the mandibles, and a new set of CT scans was obtained. Mandibles with implants were sectioned, enabling direct observation. RESULTS Based on 3000 measurements, means and standard deviations were obtained. The thickness of the mandibular alveolar bone in the cortical buccal and lingual areas, and the interradicular distances increased from the cervical toward the apical aspects. In descending order, the widest spaces were found between the first and second molars, the second premolars and the first molars, and the first and second premolars. Between the premolars, caution should be exercised starting at 9 mm from the bone crest because of the mental foramen. Between the incisors, the placement of interradicular mini-implants is not feasible. Between the first premolars and the canines, no appropriate region was found. Between the lateral incisor and the canine, at a height of 11 mm, a device can be placed but only with utmost care. CONCLUSIONS The most convenient site for implant placement in a mandible was between the first and second molars, with a 10 degrees to 20 degrees inclination, but orthodontic mini-implants should not exceed 1.5 mm in diameter and 6 mm in length.

Assessment of enamel damage after removal of ceramic brackets

INTRODUCTION Since the introduction of ceramic brackets, research has been performed to evaluate enamel damage caused during their removal. One problem in comparing treated and control groups is the absence of assurance that the surfaces were undamaged before the brackets were bonded and debonded, or that superficial treatment applied to the enamel could hinder damage detection. The aim of this in-vitro study was to evaluate enamel injuries during debonding of 3 types of ceramic brackets. METHODS Forty-five premolars, extracted for orthodontic purposes, were divided into 3 groups of 15. The enamel surfaces were photographed with a magnifying loupe (60 times) in an optical stereomicroscope (Stemi 2000-C, Zeiss, Oberkochen, Germany) with a digital camera. A different type of backet was bonded and debonded in each group: mechanical retention, mechanical retention with a polymer base, and chemical retention. After debonding, the surfaces were again photographed. The photographs were evaluated for quality of enamel surface according to a predetermined scale. The results were tested by method error and the chi-square test. RESULTS The damage evaluation comparing the same surface before bonding and after debonding showed no significant statistical difference between the mechanical retention group and the polymer base retention group. There was a significant statistical difference (P <0.05) for the chemical adhesion ceramic bracket group. CONCLUSIONS The difference between the enamel surfaces before bonding and after debonding brackets with chemical retention was statistically significant; bonding and debonding these brackets resulted in enamel damage.

Immediate vs late orthodontic extrusion of traumatically intruded teeth

Although the published papers about this matter is limited to clinical case reports, the aim of this review was to quantify the success rate of immediate vs late orthodontic extrusion of traumatically intruded teeth. From 55 reports in a PubMed and Medline computerized search, 13 reported patients involving 22 traumatically intruded anterior upper teeth with orthodontic extrusion were selected. In the sample of 13 patients, six were males and seven females and the average age was 16.4 years old. The selection criteria were patients presenting traumatized anterior upper teeth resulting in intrusive luxation, with at least 1 year follow-up period. Orthodontic extrusive forces were applied in the immediate group within 10 weeks post-trauma, while in the late group the forces were applied only after 3 months post-trauma. Immediate and late orthodontic extrusion was extremely favorable. The success rate (without or with complications) was 95.4% against only 4.5% (1 tooth) because of inflammatory root resorption with rapid progression. All mature teeth (100%) were endodontically treated. Among the 12 immature traumatically intruded teeth, eight were endodontically treated and four were not. A high rate of success was reported in the literature in traumatically intruded teeth orthodontically extruded, either immediate or late.

Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion

This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.

Influence of certain tooth characteristics on the esthetic evaluation of a smile

Ten digital photographs of a woman’s smile were modified using Adobe Photoshop software. The follow -ing changes were performed: stain removal; incisal edge straightening; gingival leveling; closure of black triangles. A group of 60 undergraduate dental students evaluated the original photograph and the altered images using a visual analog scale to evaluate smile esthetics. Intraexaminer agreement was checked for 30 examiners using the Student t test; for casual error, the Dahlberg formula was used. Data were described as means and standard devia-tions, and reported in tables.

The optimal position for insertion of orthodontic miniscrews

PURPOSE: Miniscrews feature several advantages over other devices used to achieve anchorage; however, using computed tomography (CT) scans to determine the appropriate areas to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular spaces for miniscrew placement in the mandible and maxilla. METHODS: Using CT images from 12 adult patients, mean interradicular distance and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. The means were compared with mean data from the literature. RESULTS: Considering a height of 3 mm, the most favorable mandibular interradicular distances were found between the first and second molars, first and second premolars, and finally between the canines and first premolars. The most favorable maxillary interradicular spaces were found between the canines and first premolars, between premolars, and between the second premolar and first molar. CONCLUSION: The safest interradicular site for miniscrew insertion in the mandible was found to be between the first and second molars, whereas in the maxilla, this site was between the canines and first premolars.

Avaliação da densidade óssea para instalação de mini-implantes

INTRODUCAO: alem da espessura da cortical ossea e da largura dos espacos inter-radiculares, a densidade ossea e fator primordial para a eficiencia dos mini-implantes usados como recurso de ancoragem. OBJETIVO: nesse estudo, pretendeu-se avaliar a densidade ossea alveolar e basal maxilar e mandibular, em unidades Hounsfield (HU). METODOS: em onze arquivos de imagens tomograficas computadorizadas Cone-Beam, de individuos adultos, foram obtidas 660 medidas das densidades osseas alveolar (corticais vestibular e lingual), do osso medular e basal (maxilar e mandibular). Os valores foram obtidos atraves do software Mimics 10.01 (Materialise, Belgica). RESULTADOS: maxila - a densidade da cortical vestibular na faixa de osso alveolar variou de 438 a 948HU, e a lingual de 680 a 950HU; ja o osso medular variou de 207 a 488HU; a densidade da cortical vestibular na faixa de osso basal apresentou uma variacao de 672 a 1380HU e o osso medular de 186 a 420HU. Mandibula - a variacao do osso na cortical vestibular na faixa de osso alveolar foi de 782 a 1610HU, na cortical lingual alveolar de 610 a 1301HU, e na medular de 224 a 538; a densidade na area basal foi de 1145 a 1363HU na cortical vestibular, e de 184 a 485HU na medular. CONCLUSOES: a maior densidade ossea na maxila foi observada entre pre-molares na cortical alveolar vestibular. A tuberosidade maxilar foi a regiao com menor densidade ossea. A densidade ossea na mandibula foi maior do que na maxila, e observou-se um acrescimo progressivo de anterior para posterior e de alveolar para basal

Grau de aceitação de mini-implantes por pacientes em tratamento ortodôntico: estudo preliminar

OBJECTIVE: Actually, mini-implants as anchorage resources have been spotlight in Orthodontics, providing maximum anchorage with minimum patients cooperation. However, there are still some restrictions regarding the use of these temporary anchorage devices, and among these, the psychological aspects and the patients acceptance, which still not properly evaluated. METHODS: Ten adults patients, with Class I biprotrusion malocclusion, that were submitted to orthodontic treatment with the implantation of four mini-implants, in the dental arches, among upper and lower first molar and second premolar teeth, in a total of 40 mini-implants, answered a questionnaire elaborated to evaluate the acceptance conditions of mini-implants by this patients. RESULTS: The answers obtained from the questionnaires were transformed in percentage and indicated that: most patients accepted quickly the procedure (90%); with some preoccupation with the surgical procedures (50%); 50% related no discomfort; on average they tolerated the mini-implants in 3 days; 90% were satisfied with the treatment; and 90% would recommend the treatment to others patients. Most patients tolerated mini-implant during all time of the orthodontic treatment. CONCLUSIONS: According to the results obtained with the present evaluation, it can be concluded that the mini-implants acceptance was very prominent by the patients. Larger samples´ studies are necessary.

Composição química e aspecto superficial do slot de braquetes metálicos

AIM: To evaluate the elemental composition and the slot roughness of 90 metallic brackets divided into 9 groups: group 1 - stainless steel (Equilibrium 2 - Dentaurum); group 2 - titanium (Equilibrium ti - Dentaurum); group 3 - chromium-cobalt (Topic - Dentaurum); group 4 - stainless steel (Standard - TP Orthodontics); group 5 - stainless steel (Serie light - American Orthodontics); group 6 - stainless steel (Kirium Line - Abzil Lancer); group 7 - stainless steel (Monobloc - Morelli); group 8 - stainless steel (Standard - Morelli) and group 9 - stainless steel (Monobloc Golden - Morelli). METHODS: Elemental composition was evaluated using the Spectroscopy of Dispersive Energy. The qualitative slot surface evaluation was assessed using a 500X scanning electron microscope. The microphotography was classified according to surface characteristics in 0-8 values. RESULTS: Elemental composition - group 1 = 100% titanium alloy; group 9 = 99,48% of titanium nitride coated. Group 3 = cobalt-chromium alloy; Group 8 = nickel free stainless steel alloy; other groups stainless steel alloy. Surface evaluation - Group 1 = value 2 (smoothest surface); Groups 2, 5 and 7 =value 3 (smooth surface); Groups 3, 8 and 9 showed value 6 (roughness surface); Group 4 = value 6,5 (the most roughness and irregular surface); and Group 6 has intermediate characteristics among the groups, with value 5. CONCLUSIONS: Metallic brackets were composed of different alloys and they were available with a small percentage or no nickel. The surface roughness was similar for both titanium and stainless steel, however the titanium nitride coated and cobalt-chromium showed an irregular and rough surface.

Genetic polymorphisms underlying the skeletal Class III phenotype

Introduction: Our goal was to verify the association between candidate polymorphisms and skeletal Class III malocclusion in a well‐characterized homogeneous sample set. Methods: Thirty‐five single‐nucleotide polymorphisms were studied from 10 candidate loci in 54 Class III subjects and 120 controls. Skeletal Class III characteristics included ANB angle less than 0°, SNB angle greater than 83° (mandibular prognathism), SNA angle less than 79° (maxillary deficiency), Class III molar relationship, and negative overjet. Inclusion criteria for the controls were ANB angle between 0° and 4°, Class I molar relationship, and normal overjet. Chi‐square and Fisher exact tests and principal component (PC) analysis were used to determine overrepresentation of marker alleles with alpha of 0.05. Odds ratios and 95% confidence intervals were calculated. Results: MYO1H (rs10850110 A<G) (P <0.01; odds ratio, 7.44 [4.02‐13.77]) was associated with an increased risk for the mandibular prognathism phenotype. These results were confirmed by PC analysis, which showed 4 PCs representing the sample variations (PC1, 37.24%; PC2, 20.02%; PC3, 12.18%; and PC4, 11.40%), and PC1 was associated with MYO1H (P <0.001). We also found by PC analysis associations between MYO1H (P <0.001) and GHR (rs2973015 A>G) (P = 0.001) with PC2 and between FGF10 (rs593307 A<G) (P = 0.001) with PC4. Conclusions: Polymorphism in MYO1H could be used as a marker for genetic susceptibility to Class III malocclusion with mandibular prognathism, and polymorphisms in GHR and FGF were associated with maxillomandibular discrepancies. This study may contribute to improved diagnosis and further research assessing possible differences in treatment responses based on genetic polymorphisms. HighlightsMandibular prognathism is the principal and most frequent component of skeletal Class III malocclusion.Class III prognathism is associated with MYO1H.Genes such MYO1H, GHR, and FGF10 also appear to contribute to maxillomandibular discrepancies.