Effects of Herbst Appliance Treatment on the Mandibular Incisor Segment: a Three-Dimensionally Analysis

Three-dimensionally evaluation of the treatment changes of a Herbst appliance using a lower anchorage unit not touching the lingual surface of the lower incisors. The sample consisted of 23 Class II:1 patients (12 males, 11 females) with a mean age of 15.7±1.7 years treated with a Flip-Lock Herbst® appliance (TP Orthodontics, Inc., La Porte, IN, USA). The lower anchorage unit for the Herbst appliance consisted of two anchor bands connected by a lingual arch with 3mm distance from the incisor’s lingual surface. Treatment changes in mandibular incisor inclination, overjet and overbite were evaluated by means of cone beam computed tomography images (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtained before and after treatment with the Herbst appliance. On average, there was a statistically significant increase in mandibular incisor inclination (2.6+1.8°) and a reduction in overjet (3.2+2.2mm) and overbite (1.3+0.9mm). Genders did not differ significantly. Incisor proclination was however only seen in 74% of the patients. The changes in mandibular incisor inclination were associated with the changes in overjet (/r/ = 0.1 to 0.5) and overbite (/r/ = 0.3 to 0.7). A Herbst appliance with a mandibular anchorage unit distant from the incisor’s lingual surface results in smaller amounts of mandibular incisor proclination compared to literature. However, as it induces canine anchorage loss, the decreased amount of proclination may not prevail after multibracket treatment. Keywords: Cone-Beam Computed Tomography. Mandibular Advancement. Tooth Movement Techniques. ResumoAvaliação tridimensional das alterações induzidas pelo aparelho Herbst utilizando a unidade de ancoragem inferior afastada da superfície lingual dos incisivos. A amostra incluiu 23 pacientes Classe II:1 (12 masculino, 11 feminino), média de idade 15,7 ± 1,7, tratados com aparelho Herbst Flip-Lock® (TP Orthodontics, Inc., La Porte, IN, EUA). A unidade de ancoragem inferior do aparelho Herbst consistiu-se de duas bandas conectadas por um arco lingual afastado 3mm da superfície lingual do incisivo. As alterações induzidas pelo tratamento na inclinação dos incisivos inferiores, trespasse horizontal e trespasse vertical foram avaliadas por meio de imagens de tomografias computadorizadas de feixe cônico (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtidas antes e após o tratamento com aparelho Herbst. Na média, houve diferença significativa com aumento da inclinação dos incisivos inferiores (2,6+1,8°) e diminuição do trespasse horizontal (3,2+2,2mm) e do trespasse vertical (1,3+0,9mm). Não houve diferença estatística entre os sexos. No entanto, a vestibularização do incisivo ocorreu em apenas 74% dos pacientes. As alterações na inclinação dos incisivos inferiores apresentam correlação estatisticamente significativa com as alterações no trepasse horizontal (/r/ = 0,1 a 0,5) e no trespasse vertical (/r/ = 0,3 a 0,7). O aparelho Herbst com uma unidade de ancoragem inferior afastada da superfície lingual dos incisivos resulta em menor quantidade de vestibularização do incisivo inferior em comparação com a literatura. Entretanto, como isto induz perda de ancoragem do canino, a diminuição da vestibularização pode não prevalecer ao final tratamento ortodôntico com braquetes. Palavras-chave: Tomografia Computadorizada de Feixe Cônico. Avanço Mandibular. Técnicas de Movimentação Dentária.

Bioelectrical signal associated with sweet taste transduction in humans is a hyperpolarizing potential on the lingual epithelium

The lingual surface potential (LSP), which hyperpolarizes in response to salt and bitter stimuli, is thought to be a bioelectrical signal associated with taste transduction in humans. In contrast, a recent study reported sweet and sour stimuli to evoke a depolarization of the LSP. We questioned the origin of such a depolarization because liquid junction potentials (JPs), which arise at the interfaces of recording electrode and taste solutions, are neglected in the report. We recorded the LSPs to sucrose and NaCl solutions on the human tongue using an Ag/AgCl electrode. To estimate JPs generated by each taste solution, we made an agar model to simulate the human tongue. The lingual surface was rinsed with a 10 mM NaCl solution that mimics the sodium content of the lingual fluid. In the human tongue, sucrose dissolved in distilled water evoked a depolarizing LSP that could be attributed to JPs, resulting from the change in electrolyte concentration of the taste solution. Sucrose dissolved in 10 mM NaCl solution evoked a hyperpolarizing LSP which became more negative in a concentration-dependent manner (300–1500 mM). Lactisole (3.75 mM), an inhibitor of sweet taste, significantly reduced the LSPs and decreased perceived intensity of sweetness by human subjects. The negative JPs generated by 100 mM NaCl in the agar model were not different from the LSPs to 100 mM NaCl. When the electrolyte environment on the lingual surface is controlled for JPs, the bioelectrical signal associated with sweet taste transduction is a hyperpolarizing potential.

3D technology to measure dental arches and create a template for lingual brackets technique

ABSTRACT Objective: This study aims at identifying anatomical dimensions of dental arches, based on landmarks currently used in the lingual orthodontic technique, and create an archwire form template to be used in orthodontic clinics. Methods: Maxillary and mandibular dental casts of 140 Caucasian individuals with natural and normal occlusion were digitized (3D), and the images were analyzed with Delcam Power ShapeTM 2010 software. The dental arch shapes and sizes were obtained from 14 landmarks selected on the lingual surface of the teeth. Points and segments defined by the software were used to create an archwire form template. Results: Various dental arch patterns were found for both maxilla and mandible. The smallest sizes were found in females, and the largest were found in male subjects. Six categories were defined for each gender, three for the maxilla and three for the mandible (Small, Medium and Large). A template was created with eighteen anatomic lingual archwire designs, nine for the maxilla and nine for the mandible, for both genders. Conclusions: Landmarks evaluated in this study showed dental arch differences between genders. This information enables making orthodontic lingual archwires that are more compatible with the anatomical forms and sizes of the maxilla and mandible. The findings also allowed the creation of a template for an anatomic lingual metallic archwire form to be used in the lingual technique.

Analysis of the Association of Foramen Cecum and Dens in Dente in Maxillary Lateral Incisor

Objectives The aim of this study was to evaluate the frequency of foramen cecum and dens in dente, and to verify the association of these structures in the maxillary lateral incisor (MLI). Materials and Methods The presence of foramen cecum in the lingual surface of 110 MLI was verified, and the teeth were radiographed to observe the presence of dens in dente, being classified according to the literature. An association study between the presence of foramen cecum and dens in dente was performed using the Cramer’s V and chi-square statistical tests. Results The association was statistically significant between the foramen cecum and the dens in dente. Concomitant presence was observed in 17.27%, being a high rate when compared with the presence of foramen cecum alone (9.09%) or dens in dente alone (8.18%). In addition, type I (minimal invagination, confined to the crown of the tooth and not extending beyond the level of the cementum–enamel junction) was the most frequent (82.14%). Conclusions We emphasize the importance of alerting the dentist to the presence of a foramen cecum on the lingual surface of the MLI, as it is likely that dens in dente is usually of type I. Thus, the foramen cecum is a sign that can assist the dental surgeon in the discovery of dens in dente and clinical conduct to be taken.

Effects of Herbst Appliance Treatment on the Mandibular Incisor Segment: A 3-D Analysis

Background: Three-dimensionally evaluation of the treatment changes of a Herbst appliance using a lower anchorage unit not touching the lingual surface of the lower incisors. Methods: 23 Class II:1 patients (12 males, 11 females) with a mean age of 15.7±1.7 years treated with a Flip-Lock Herbst® (TP Orthodontics, Inc., La Porte, IN, USA) appliance. The lower anchorage unit for the Herbst appliance consisted of two anchor bands connected by a lingual arch with 3mm distance from the incisor’s lingual surface. Treatment changes in mandibular incisor inclination, overjet and overbite were evaluated by means of cone beam computed tomography images (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtained before and after treatment with the Herbst appliance. Results: On average, there was a statistically significant increase in mandibular incisor inclination (2.6+1.8°) and a reduction in overjet (3.2+2.2mm) and overbite (1.3+0.9mm). Genders did not differ significantly. Incisor proclination was however only seen in 74% of the patients. The changes in mandibular incisor inclination were associated with the changes in overjet (/r/ = 0.1 to 0.5) and overbite (/r/ = 0.3 to 0.7). Conclusion: A Herbst appliance with a mandibular anchorage unit distant from the incisor’s lingual surface results in smaller amounts of mandibular incisor proclination compared to literature. However, as it induces canine anchorage loss, the decreased amount of proclination may not prevail after multibracket treatment. Trial registration: This study was registered 08 February 2011, reviewed and approved by the Ethics Committee of Araraquara Dental School, Paulista State University (FOAr-UNESP), project number 62/2010. https://www.foar.unesp.br/#!/comissoes-e-comites/cep/

Impact of proximal cavities and primary molar absence on space in the dental arches

Background A recently proposed treatment protocol for dental caries in primary teeth, called Ultra Conservative Treatment (UCT), keeps medium to large cavities open so that children can keep them clean with tooth brushing and fluoride toothpaste. However, carious lesions have been related to malocclusion and decrease of space for the eruption of the permanent successor. Methods This cross-sectional study evaluated dental casts of 235 schoolchildren, aged 6–7 years old of six public schools in deprived suburban areas, and with at least two cavitated dentin carious lesions. The casts were grouped according to the location of cavitated dentin lesions into non-proximal cavity (NPC), proximal cavity with buccal or lingual surface contact point to adjacent tooth (PCCP) and proximal cavity without contact to adjacent tooth (PCWC), as well as the absence of primary molars due carious lesions (PMA). The relationship between location of cavitated dentin lesions or absence of primary molars with C+D+E and D+E space was analyzed. Results Children with absence of primary molars exhibited the smallest C+D+E and D+E space in the maxilla (P < 0.001) and mandible (P < 0.001), followed by proximal cavity without buccal or lingual surface contact. No significant difference was observed between NPC and PCCP groups in upper and lower arches. Discussion PCWC are associated with minor (less than the leeway space) C+D+E and D+E space loss in both arches, and additional space loss is noted when primary molars are prematurely lost. These results may have implications for orthodontic and restorative dental care decisions in children.