Prediction of maxillary canine impaction based on panoramic radiographs.

OBJECTIVES: The objective of this article is to establish a large sample-based prediction model for maxillary canine impaction based on linear and angular measurements on panoramic radiographs and to validate this model. MATERIALS AND METHODS: All patients with at least two panoramic radiographs taken between the ages of 7 and 14 years with an interval of minimum 1 year and maximum 3 years (T1 and T2) were selected from the Department of Oral Health Sciences, University Hospital Leuven database. Linear and angular measurements were performed at T1. From 2361 records, 572 patients with unilateral or bilateral canine impaction were selected at T1. Of those, 306 patients were still untreated at T2 and were used as study sample. To construct the prediction model, logistic regression analysis was used. RESULTS: The parameters analyzed through backward selection procedure were canine to midline angle, canine to first premolar angle, canine cusp to midline distance, canine cusp to maxillary plane distance, sector, quadratic trends for continuous predictors, and all pairwise interactions. The final model was applied to calculate the likelihood of impaction and yielded an area under the curve equal to 0.783 (95% CI [0.742-0.823]). The cut-off point was fixed on 0.342 with a sensitivity of 0.800 and a specificity of 0.598. The cross-validated area under the curve was equal to 0.750 (95% CI [0.700, 0.799]). CONCLUSION: The prediction model based on the above mentioned parameters measured on panoramic radiographs is a valuable tool to decide between early intervention and regular follow-up of impacted canines.

In silico study of cuspid' periodontal ligament damage under parafunctional and traumatic conditions of whole-mouth occlusions. A patient-specific evaluation.

BACKGROUND AND OBJECTIVE: Although traumatic loading has been associated with periodontal ligament (PDL) damage and therefore with several oral disorders, the damage phenomena and the traumatic loads involved are still unclear. The complex composition and extremely thin size of the PDL make experimentation difficult, requiring computational studies that consider the macroscopic loading conditions, the microscopic composition and fine detailed geometry of the tissue. In this study, a new methodology to analyse the damage phenomena in the collagen network and the extracellular matrix of the PDL caused by parafunctional and traumatic occlusal forces was proposed. METHODS: The entire human mandible and a portion thereof containing a full cuspid tooth were separately modelled using finite element analysis based on computed tomography and micro-computed tomography images, respectively. The first model was experimentally validated by occlusion analysis and subjected to the muscle loads produced during hard and soft chewing, traumatic cuspid occlusion, grinding, clenching, and simultaneous grinding and clenching. The occlusal forces computed by the first model were subsequently applied to the single tooth model to evaluate damage to the collagen network and the extracellular matrix of the PDL. RESULTS: Early occlusal contact on the left cuspid tooth guided the mandible to the more occluded side (16.5% greater in the right side) and absorbed most of the lateral load. The intrusive occlusal loads on the posterior teeth were 0.77-13.3% greater than those on the cuspid. According to our findings, damage to the collagen network and the extracellular matrix of the PDL could occur in traumatic and grinding conditions, mainly due to fibre overstretching (>60%) and interstitial fluid overpressure (>4.7 kPa), respectively. CONCLUSIONS: Our findings provide important biomechanical insights into the determination of damage mechanisms which are caused by mechanical loading and the key role of the porous-fibrous behaviour of the PDL in parafunctional and traumatic loading scenarios. Besides, the 3D loading conditions computed from occlusal contacts will help future studies in the design of new orthodontics appliances and encourage the application of computing methods in medical practice.

Effect of orthodontic force magnitude on cytokine networks in gingival crevicular fluid: a longitudinal randomized split-mouth study.

OBJECTIVE: To compare effect of two different orthodontic forces on maxillary canine distalization via evaluation of 30 analytes including cytokines, growth factors, and chemokines in gingival crevicular fluid (GCF) obtained from tension and compression sites. DESIGN: Longitudinal, split-mouth, randomized controlled trial. METHODS: The upper right and left canines were randomly distalized by a continuous force of either 75 or 150 g, in 15 individuals with Class II division 1 malocclusion. GCF samples were obtained from the tension and the pressure sides of each canine at appliance placement (baseline) and after force application at 24 hours and 28 days without reactivation of the coil spring. The protein content of GCF was analysed by a multiplexed immunoassay. The effects of force, side, and time on the analyte levels were assessed by the Brunner-Langer method. OUTCOME: The changes of GCF analyte levels from baseline to 24 hours and 28 days. RANDOMIZATION: Coin flipping was used for allocation of two forces. BLINDING: The participants and periodontist who performed clinical measurements and GCF sampling were blinded to group assignment and interventions (double-blinded trial). RESULTS: All patients completed the study. No harm was observed. When compared to baseline, both forces caused significant up-regulation of tumour necrosis factor-α and interleukin (IL)-1RA in the tension and the pressure sides at 28 days (P < 0.05), but not at 24 hours. Although GCF volume was similar between the two force groups over time (P > 0.05), IL-8 and MCP-1 levels in GCF were significantly lower at the pressure sites receiving higher force (150 g) at 24 hours (P < 0.05). LIMITATIONS: Although sample size (15 patients, 30 teeth) was adequate according to the initial power calculation, borderline significances may indicate lack of power or large variability among the samples. CONCLUSIONS: Although a higher force of 150 g did not result in increased cumulative canine movement or GCF production, selective host mediators were differentially regulated by the magnitude and duration of the force. REGISTRATION AND TRIAL PROTOCOL: The trial was registered retrospectively in the U.S. National Institutes of Health Clinical Trials Registry. Full details of trial protocol NCT03555747 are available on request.

Apical Microleakage in Root Canals Obturated With 2 Different Endodontic Sealer Systems in Canine Teeth of Dogs.

An apical dye leakage test was utilized to compare 2 endodontic sealer systems commonly used in veterinary endodontic treatment. Rotary instrumentation followed by injection of 2 different sealers (GuttaFlow 2 and AH Plus) and a single master cone obturation technique were compared. Following obturation and restoration, specimens were immersed in India ink for 48 hours. A tooth mineral clearing technique was utilized to render the tooth samples transparent. Subsequently, the apices were evaluated for prevalence and magnitude of apical dye penetration under magnification. Statistical analysis of the results revealed no significant differences in the prevalence or magnitude of apical dye penetration between groups.

Management of Mesioverted Maxillary Canine Teeth and Linguoverted Mandibular Canine Teeth.

Mesioverted maxillary canine teeth in combination with linguoverted mandibular canine teeth are a common ramification of persistent deciduous maxillary and mandibular canine teeth. Without the physical presence of the mandibular canine teeth, the maxillary third incisor and canine teeth diastemata are frequently narrowed. The creation of normal occlusion requires treatment of all 4 canine teeth; the mandibular canine teeth must be tipped labially and the maxillary canine teeth must be tipped and/or partially translated distally. This case report discusses the novel integration of 2 well-described orthodontic techniques to simultaneously treat both mesioverted maxillary canine teeth and linguoverted mandibular canine teeth, achieving a comfortable, functional occlusion.

Caninos superiores retenidos por palatino: radiografía panorámica para evaluar ubicarlos en el arco dentario / Palatally impacted upper canines: panoramic radiography to assess their location in the dental arch

Los caninos superiores permanentes, estadísticamente, se encuentran entre las piezas dentarias que con más frecuencia quedan en retención ósea,después de los terceros molares.Sin embargo, los caninos, estética, funcionalmente, y para mantenimiento de las relaciones contactantes,a la hora de valorarlos en boca, desempeñan una función más importante que los terceros molares. Por eso la importancia de poder ubicarlos en el arco dentario. Cuando los ortodoncistas, sobre todo los menos experimentados, se enfrentan a la decisión de conservar los caninos que se encuentran en posiciones deretención ósea palatina, son muchos los interrogantes que se le plantean sobre su posible ubicación con éxito, en el arco dentario. Frecuentemente está la duda de cuál es el límite de la posición de retención para intentar su acomodamiento. Proponemos un simple trazado que se puede hacersobre la ortopantomografia panorámica, marcando dos líneas tangentes a la pared externa delas fosas nasales que se continuarán con los ejes longitudinales de los caninos retenidos de ambos lados. Si queda constituida una figura geométrica de apariencia de un rombo, significa que el extremo de la raíz se encuentra próximo a la posición que anatómicamente le pertenece (fosa canina del maxilar superior), existiendo una alta probabilidad de concluir con éxito su ubicación en el arco dentario.

Statiscally, permanent upper canines are the mostfrequently impacted teeth, after third molars.Upper canines though, have more significancethan third molars aesthetically, functionally andin maintaining contacting relations;thus the importance of bringing them inthe correct position within the dental arch.When an Orthodontist, particularly those lessexperienced, are faced with the decision ofmaintaining canines impacted in the palatal bone;many questions linger regarding the possibilitiesof successful relocation into the dental arch.Frequently, the question lays in the limitationsof moving it from its impacted positionto the correct one.We propose a simple tracing of theOrthopantomogram (OPG), marking twotangent lines to the lateral wall of the nasal cavitycontinuing on the long axis of the impactedcanines of both sides. If the result is a geometricfigure resembling a rhombus, it means thatthe radicular apex is close to the correctanatomical position (maxillary canine fossa),indicating high probabilities of successfullypositioning the impacted tooth.

Finite element analysis to study the effects of using CAD/CAM glass-fiber post system in a severely damaged anterior tooth.

To investigate the stress distribution of a severely damaged maxillary anterior tooth restored with a computer-aided design/computer-aided manufacturing (CAD/CAM) glass-fiber post system. Twelve models were fabricated with different alveolar bone levels and cervical dentin wall thicknesses and studied using a two-dimensional finite element method. A force of 100 N was applied to the lingual surface of the crown at 45 degrees, and the maximum von Mises stress was calculated. A higher stress level was observed in the dentin than in the post and crown. With the reduction of dentin thickness, the maximum von Mises stress in the dentin increased slightly to a peak at a thickness of 1.5 mm, followed by a slight decrease at a thickness of 1.0 mm. However, the relative ratio (RR) values did not show a large difference (RR > 80%). Meanwhile, a large difference in RR values was observed with a change in bone level (RR < 80%). When using a CAD/CAM glass-fiber post system, the maximal von Mises stress was significantly affected by the bone level, rather than by the dentin thickness. Moreover, this system may be applied to the treatment of a maxillary anterior tooth with a bone level of only 2/3.

Axonal Degeneration in Dental Pulp Precedes Human Primary Teeth Exfoliation.

The dental pulp in human primary teeth is densely innervated by a plethora of nerve endings at the coronal pulp-dentin interface. This study analyzed how the physiological root resorption (PRR) process affects dental pulp innervation before exfoliation of primary teeth. Forty-four primary canine teeth, classified into 3 defined PRR stages (early, middle, and advanced) were fixed and demineralized. Longitudinal cryosections of each tooth were stained for immunohistochemical and quantitative analysis of dental pulp nerve fibers and associated components with confocal and electron microscopy. During PRR, axonal degeneration was prominent and progressive in a Wallerian-like scheme, comprising nerve fiber bundles and nerve endings within the coronal and root pulp. Neurofilament fragmentation increased significantly during PRR progression and was accompanied by myelin degradation and a progressive loss of myelinated axons. Myelin sheath degradation involved activation of autophagic activity by Schwann cells to remove myelin debris. These cells expressed a sequence of responses comprising dedifferentiation, proliferative activity, GAP-43 overexpression, and Büngner band formation. During the advanced PRR stage, increased immune cell recruitment within the dental pulp and major histocompatibility complex (MHC) class II upregulation by Schwann cells characterized an inflammatory condition associated with the denervation process in preexfoliative primary teeth. The ensuing loss of dental pulp axons is likely to be responsible for the progressive reduction of sensory function of the dental pulp during preexfoliative stages.

Antimicrobial Effects of Novel Triple Antibiotic Paste-Mimic Scaffolds on Actinomyces naeslundii Biofilm.

INTRODUCTION: Actinomyces naeslundii has been recovered from traumatized permanent teeth diagnosed with necrotic pulps. In this work, a triple antibiotic paste (TAP)-mimic scaffold is proposed as a drug-delivery strategy to eliminate A. naeslundii dentin biofilm. METHODS: Metronidazole, ciprofloxacin, and minocycline were added to a polydioxanone (PDS) polymer solution and spun into fibrous scaffolds. Fiber morphology, mechanical properties, and drug release were investigated by using scanning electron microscopy, microtensile testing, and high-performance liquid chromatography, respectively. Human dentin specimens (4 × 4 × 1 mm(3), n = 4/group) were inoculated with A. naeslundii (ATCC 43146) for 7 days for biofilm formation. The infected dentin specimens were exposed to TAP-mimic scaffolds, TAP solution (positive control), and pure PDS (drug-free scaffold). Dentin infected (7-day biofilm) specimens were used for comparison (negative control). Confocal laser scanning microscopy was done to determine bacterial viability. RESULTS: Scaffolds displayed a submicron mean fiber diameter (PDS = 689 ± 312 nm and TAP-mimic = 718 ± 125 nm). Overall, TAP-mimic scaffolds showed significantly (P ≤ .040) lower mechanical properties than PDS. Within the first 24 hours, a burst release for all drugs was seen. A sustained maintenance of metronidazole and ciprofloxacin was observed over 4 weeks, but not for minocycline. Confocal laser scanning microscopy demonstrated complete elimination of all viable bacteria exposed to the TAP solution. Meanwhile, TAP-mimic scaffolds led to a significant (P < .05) reduction in the percentage of viable bacteria compared with the negative control and PDS. CONCLUSIONS: Our findings suggest that TAP-mimic scaffolds hold significant potential in the eradication/elimination of bacterial biofilm, a critical step in regenerative endodontics.

Evaluation of dental age and associated developmental anomalies in subjects with impacted mandibular canines.

OBJECTIVES: To assess the null hypothesis that there is no difference in the rate of dental development and the occurrence of selected developmental anomalies related to shape, number, structure, and position of teeth between subjects with impacted mandibular canines and those with normally erupted canines. MATERIALS AND METHODS: Pretreatment records of 42 subjects diagnosed with mandibular canines impaction (impaction group: IG) were compared with those of 84 subjects serving as a control reference sample (control group: CG). Independent t-tests were used to compare mean dental ages between the groups. Intergroup differences in distribution of subjects based on the rate of dental development and occurrence of selected dental anomalies were assessed using χ(2) tests. Odds of late, normal, and early developers and various categories of developmental anomalies between the IG and the CG were evaluated in terms of odds ratios. RESULTS: Mean dental age for the IG was lower than that for the CG in general. Specifically, this was true for girls (P < .05). Differences in the distribution of the subjects based on the rate of dental development and occurrence of positional anomalies also reached statistical significance (P < .05). The IG showed a higher frequency of late developers and positional anomalies compared with controls (odds ratios 3.00 and 2.82, respectively; P < .05). CONCLUSIONS: The null hypothesis was rejected. We identified close association of female subjects in the IG with retarded dental development compared with the female orthodontic patients. Increased frequency of positional developmental anomalies was also remarkable in the IG.

Diámetro mesiodistal de incisivos y caninos superiores e inferiores. Índices incisivos, Matanzas, 2012 / Mesiodistal diameter of upper and low incisors and canines. Incisal indexes, Matanzas, 2012

El tamaño de los dientes permite establecer un diagnóstico precoz de la falta de espacio para su ubicación futura en el arco dentario y practicar tratamientos interceptivos tempranos. El propósito de este trabajo fue determinar el diámetro mesiodistal de incisivos y caninos superior e inferior, y los índices incisivos superior e inferior, con la finalidad de establecer valores propios de esta población, que contribuyan a elevar la calidad del diagnóstico en Ortodoncia. Fue realizado un estudio descriptivo y transversal en sujetos con oclusión normal, en una muestra de 362 estudiantes: 174 del sexo femenino y 188 del masculino, distribuidos en 143 de doce, 106 de trece y 113 de catorce años, respectivamente, seleccionados en las escuelas secundarias básicas de la ciudad de Matanzas. Las mediciones fueron realizadas por un solo observador, directamente en la boca desde el punto de contacto mesial hasta distal a nivel de su mayor diámetro con el empleo de un pie de rey. Las variables empleadas fueron edad, sexo y diámetro mesiodistal de los dientes. Se determinaron los diámetros mesodistales en los dientes de la arcada superior e inferior con similares tamaños entre ambos lados derechos e izquierdos y los índices incisivos superior (31,20 mm) e inferior (22,70 mm). Se determinó dimorfismo sexual, sustentado en mayor tamaño de los incisivos laterales (P= 0,008), y caninos derechos superiores (P= 0,000) en los varones, así como también en los incisivos laterales derechos (P= 0,001) y caninos derechos (P= 0,000) inferiores en este mismo sexo(AU)

Teeth size allows arriving to a precocious diagnosis of the lack of space for their future location in the dental arch and practicing early interceptive treatments. The aim of this work was finding out the mesiodistal diameter of upper and low incisors and canines, and the upper and low incisal indexes, with the objective of establishing this population own values contributing to the diagnosis quality improvement in Orthodontics. We carried out a cross-sectional descriptive study in people with normal occlusion, in a sample of 362 students: 174 females and 188 males, 143 aged 12 years, 106 aged 13 years and 133 aged 14 years, selected in the secondary schools of the city of Matanzas. Measures were taken by only one person, directly in the mouth, from the mesial contact point to the distal one, at the level of the higher diameter using a Vernier caliper. The used variables were age, gender, and teeth mesial-distal diameter. We determined mesial-distal diameters of the upper and lower arches with similar sizes in both right and left sides, and upper (31,20 mm)and lower (22,70 mm) incisal indexes. We found sexual dimorphism, based on the males´ higher size of the lateral incisors (P= 0,008), and upper right canines (P= 0,000), and also of the right lateral incisors (P= 0,001) and low right canines (P= 0,000)(AU)

Fracture resistance of endodontically treated teeth restored with glass fiber posts of different lengths.

STATEMENT OF PROBLEM: Endodontically treated teeth are known to have reduced structural strength. Glass fiber posts may influence fracture resistance and should be evaluated. PURPOSE: The purpose of this study was to evaluate the influence of glass fiber post length on the fracture resistance of endodontically treated teeth. MATERIAL AND METHODS: Forty intact human maxillary canines were selected and divided into 4 groups, the control group consisting of teeth restored with a custom gold cast post and core, with a length of two-thirds of the root. Other groups received prefabricated glass fiber posts in different lengths: group 1/3, removal of one-third of the sealing material (5 mm); group 1/2, removal of one-half of the sealing material (7.5 mm); and group 2/3, removal of two-thirds of the sealing material (10 mm). All the posts were cemented with resin cement, and the specimens with glass fiber posts received a composite resin core. All the specimens were restored with a metal crown and submitted to a compressive load until failure occurred. The results were evaluated by 1-way ANOVA, and the all pairwise multiple comparison procedures (Tukey honestly significantly difference test) (α=.05). RESULTS: The ANOVA showed significant differences among the groups (P<.002). The Tukey test showed that the control group presented significantly higher resistance to static load than the other groups (control group, 634.94 N; group 1/3, 200.01 N; group 1/2, 212.17 N; and group 2/3, 236.08 N). Although teeth restored with a cast post and core supported a higher compressive load, all of them fractured in a catastrophic manner. For teeth restored with glass fiber posts, the failure occurred at the junction between the composite resin core and the root. CONCLUSION: The length of glass fiber posts did not influence fracture load, but cast post and cores that extended two-thirds of the root length had significantly greater fracture resistance than glass fiber posts.

Inferring biological evolution from fracture patterns in teeth.

It is hypothesised that specific tooth forms are adapted to resist fracture, in order to accommodate the high bite forces needed to secure, break down and consume food. Three distinct modes of tooth fracture are identified: longitudinal fracture, where cracks run vertically between the occlusal contact and the crown margin (or vice versa) within the enamel side wall; chipping fracture, where cracks run from near the edge of the occlusal surface to form a spall in the enamel at the side wall; and transverse fracture, where a crack runs horizontally through the entire section of the tooth to break off a fragment and expose the inner pulp. Explicit equations are presented expressing critical bite force for each fracture mode in terms of characteristic tooth dimensions. Distinctive transitions between modes occur depending on tooth form and size, and loading location and direction. Attention is focussed on the relatively flat, low-crowned molars of omnivorous mammals, including humans and other hominins and the elongate canines of living carnivores. At the same time, allusion to other tooth forms - the canines of the extinct sabre-tooth (Smilodon fatalis), the conical dentition of reptiles, and the columnar teeth of herbivores - is made to highlight the generality of the methodology. How these considerations impact on dietary behaviour in fossil and living taxa is discussed.

Effect of a crown ferrule on the fracture strength of endodontically treated canines restored with fiber posts and metal-ceramic or all-ceramic crowns.

The aim of this study was to comparatively evaluate the fracture strength of endodontically treated canines restored with glass-fiber posts (GFPs) and either metal-ceramic (MC) or all-ceramic (AC) crowns in the presence or absence of 2 mm of ferrule height. Fifty human maxillary canines were endodontically treated and randomly divided into five groups of 10 specimens each. The first group remained intact (control), while the remainder were restored with GFPs and composite cores with either MC or AC crowns. Each of the AC and MC groups was equally divided between teeth with or without ferrule. Teeth were embedded in acrylic resin and loaded at a 135-degree angle to their long axis until fracture. Fracture strength was not significantly different between ferrule and no ferrule groups (P = .571), but was significantly larger for the MC groups compared with the control and AC groups (P = .009 and P = .024, respectively). A significant effect of the type of restoration was found as teeth restored with MC crowns presented significantly higher fracture strength, independently of ferrule.

Effect of surgical exposure technique, age, and grade of impaction on ankylosis of an impacted canine, and the effect of rapid palatal expansion on eruption: A prospective clinical study.

INTRODUCTION: This study had 2 aims: (1) to assess whether the surgical exposure technique, the patient's age, and the grade of impaction are associated with ankylosis of the impacted canine; and (2) to investigate the effect of rapid palatal expansion on an impacted canine's automatic eruption. METHODS: The sample for this prospective longitudinal study consisted of 118 orthodontic patients (72 female, 46 male) who were treated surgically and orthodontically by the first author (S.I.K.) over 18 years. The patients' ages at the beginning of therapy ranged from 11.2 to 46.1 years. They had 157 impacted canines (150 maxillary, 7 mandibular), grouped in 7 categories (grades I-VII) according to their radiographic position in the orthopantomogram at the onset of treatment. Univariate and multivariate generalized estimating equation logistic regression analyses were used to assess the effect of the predictors of interest on ankylosis. (In this research, a broad definition of "ankylosis" was used, to include impacted canines immobilized a priori or during traction, due to all the possible causes that could contribute to immobilization, such as all types of external tooth resorption and other known or unknown factors.) RESULTS: Thirty-eight canines erupted spontaneously after space gaining, and the other 119 were treated surgically with an open (57 cases) or a closed (62 cases) exposure technique. Eleven canines of the 119 that were treated surgically had ankylosis, either a priori or during orthodontic traction. The percentages of ankylosis were 3.5% in the open technique and 14.5% in the closed technique. Evidence of statistical association was found between age and ankylosis, grade of impaction and ankylosis, and rapid palatal expansion and automatic eruption of the impacted canine. CONCLUSIONS: Evidence of an association between exposure technique and ankylosis was found. Additionally, there was evidence that the grade of impaction and the patient's age are significant predictors of ankylosis, as is the use of rapid palatal expansion a predictor of automatic eruption.

Unilateral delayed eruption of a mandibular permanent canine and the maxillary first and second molars, and agenesis of the maxillary third molar.

Delayed tooth eruption can affect the accuracy of orthodontic diagnosis and treatment planning and could delay overall treatment. A girl, aged 7 years 4 months, who had unilateral delayed eruption of several teeth was successfully treated. The evaluation of delayed tooth eruption should be considered by the orthodontist because the role of these teeth can affect the overall treatment of malocclusion. In patients with delayed tooth eruption, careful and accurate diagnosis and treatment planning will allow the orthodontist to start treatment at the proper stage and might reduce the overall orthodontic treatment time.

Free-end saddle length influence on stress level in unilateral complex partial denture abutment teeth and retention elements.

BACKGROUND/AIM: Different types of dental restorations are used for the therapy of unilateral free-end saddle edentulism. Unilateral complex partial denture is one of the indications for the Kennedy class II partial edentulism. The abscence of major connector and denture plate is an advantage compared to the conventional restorations, because of better comfort and shorter period of adaptation. The aim of the study was to analyse the influence of free-end saddle length change on the behaviour of unilateral complex partial denture supporting structures. METHODS: Stress levels of the canine and the first premolar as retentional teeth and the attachments were tested under the influence of physiological forces with the loading point shifting distally in relation to the saddle length change. A virtual real size 3D model of the fixed part of the restoration (the canine and the first premolar with milled crowns) was created using the CATIA computer program. It was connected to the mobile part of partial denture with the SD snap in latch attachment. Mobile part of the restoration was designed in the region of 2, 3 and 4 lateral teeth (second premolar, first, second and third molar). By using the finite element method (FEM) stress levels analysis was performed under the load of physiological forces of 150 N in the free-end saddle teeth zone. RESULTS: The results of analysis show that physiological forces cause a different stress distribution on the abutment teeth and the attachment, depending on the saddle length. CONCLUSION: The stress level values obtained for the abutment teeth as well as the attachment are far lower than the marginal ones. The behaviour of the system changes under this defined stress, but no plastic deformation occurs.

Need for further clarity on optimal approach to ectopic canines.

DESIGN: Randomised controlled trial. INTERVENTION: Patients between 8-13 years of age with either unilateral or bilateral PDC diagnosed on radiograph with the presence of mild crowding at the maxillary arch and/or molar relation showing Class II tendency were included. The head gear group (HG) used cervical pull headgear alone for one year for 12-14 hours a day, while the rapid maxillary expansion/headgear (RME/HG) group were treated with a banded rapid maxillary expander, (7 mm of active expansion; at the end of expansion all patients retained the expander for six months), followed by use of a cervical pull headgear as in the HG group. A control group received no active treatment. OUTCOME MEASURE: A successful outcome for PDC was defined as the full eruption of the tooth, thus permitting bracket positioning for final arch alignment at 18 months after the initial observation. RESULTS: Sixty of the 64 patients who entered the trial were available for final assessment. Successful eruption was 85.7% in the RME/HG group, 82.3% in the HG group and 36% in the control group. There was no statistically significant difference between the HG and RME/HG groups. CONCLUSIONS: The use of rapid maxillary expansion and headgear (or headgear alone) in PDC cases increases the success rate of eruption of the canine significantly (almost three times more than in untreated controls).

Alignment and leveling maxillary impacted canines / Alinhamento e nivelamento de caninos superiores impactados

The impaction of maxillary permanent canines is a frequently encountered clinical problem, especially on the palate. The causes for retarded eruption of the teeth may be either generalized or localized, and its diagnosis is based on both specific clinical and radiographic examinations. Combined periodontal-orthodontic treatment has been efficient when a prognostic and adequate technique is assured to preserve the integrity of the tissues around the canine teeth. This review illustrates clinical cases of maxillary impacted canines and procedures to bring them to normal axial inclination on the dental arch.

A impactação de caninos superiores permanentes é um problema clínico frequentemente encontrado, especialmente no palato. As causas para a erupção tardia dos dentes pode ser tanto generalizada ou localizada, e seu diagnóstico é baseado em exames clínicos e radiográficos específicos. O tratamento combinado periodontal-ortodôntico tem sido eficiente quando uma técnica adequada é assegurada para preservar a integridade dos tecidos ao redor dos dentes caninos. Esta revisão ilustra casos clínicos de caninos superiores impactados e procedimentos para trazê-los à inclinação axial normal no arco dentário.