Intercanine Distance Research Articles

Comparison of maxillary basal arch forms using the root apex in adult women with different skeletal patterns: A pilot study

This study aimed to establish maxillary basal arch forms using the root apices and to determine the differences in the basal arch forms in adult women with different sagittal skeletal patterns. This retrospective study included 91 adult women, with either a Class I (n=24), Class II Division 1 (n=22), Class II Division 2 (n=23), or Class III (n=22) malocclusion, who underwent cone-beam computed tomography. Three-dimensional coordinates of the root apices were determined using the multiplanar reformation mode of OnDemand3D software (Cybermed Inc, Seoul, South Korea). Two-dimensional coordinates were converted from acquired 3-dimensional coordinates via projection on the palatal plane, and the Procrustes superimposition method was used to build the basal arch form. Finally, interroot width measurements were performed for basal arch form comparisons. There were significant differences among the 4 groups (P<0.05) with respect to the intercanine width. The intercanine width of Class II Division 1 group was significantly narrower than that of the other groups. The Class II Division 1 and Class II Division 2 groups tended to have tapered arch forms and squared arch forms, respectively. We established maxillary basal arch forms using the root apices. The Class II Division 1 group had a significantly narrower intercanine distance. The use of the root apex to depict the basal arch form seems reasonable.

Avaliação da distância intercaninos e sua correlação com as más oclusões

O objetivo deste trabalho é avaliar a correlação entre a distância intercaninos e as más oclusões. Tratou-se de um estudo observacional e prospectivo, cujos dados foram coletados de 110 documentações ortodônticas e modelos de estudo, de pacientes entre 12 e 35 anos. As variáveis estudadas foram: idade, sexo, padrão racial, relação molar de Angle, más oclusões e distância intercaninos. Os dados foram anotados em formulário específico e distribuídos em tabelas, onde aplicou-se a estatística analítica através dos testes t Student e ANOVA (p&lt;0,05). Os resultados foram os seguintes: a média de idade foi de 17,7 anos; a maioria da amostra foi do sexo feminino (58,7%) e de feodermas (43,6%). A relação de Classe I apresentou maior frequência (46,4% direita; 49,1% esquerda) e a má oclusão mais prevalente foi o apinhamento dentário (67,7%). As médias das distâncias intecaninos foram: 33,98mm, para a arcada superior e 26,11mm para a interior. A distância intercaninos na arcada superior de homens, foi estatisticamente maior que nas mulheres; assim como os arcos inferiores de jovens de 12 a 20 anos, foram maiores do que os de adultos de 21 a 35 anos. Concluiu-se que não houve correlação significativa entre a distância intercaninos e as más oclusões.

Comparison of Mandibular Arch Expansion by the Schwartz Appliance Using Two Activation Protocols: A Preliminary Retrospective Clinical Study.

Background and objectives: Dental crowding is more pronounced in the mandible than in the maxilla. When exceeding a significant amount, the creation of new space is required. The mandibular expansion devices prove to be useful even if the increase in the lower arch perimeter seems to be just ascribed to the vestibular inclination of teeth. The aim of the study was to compare two activation protocols of the Schwartz appliance in terms of effectiveness, particularly with regard to how quickly crowding is solved and how smaller is the increasing of vestibular inclination of the mandibular molars. Materials and Methods: We compared two groups of patients treated with different activation’s protocols of the lower Schwartz appliance (Group 1 protocol consisted in turning the expansion screw half a turn twice every two weeks and replacing the device every four months; Group 2 was treated by using the classic activation protocol—1/4 turn every week, never replacing the device). The measurements of parameters such as intercanine distance (IC), interpremolar distance (IPM), intermolar distance (IM), arch perimeter(AP), curve of Wilson (COW), and crowding (CR) were made on dental casts at the beginning and at the end of the treatment. Results: A significant difference between protocol groups was observed in the variation of COWL between time 0 and time 1 with protocol 1 with protocol 1 subjects showing a smaller increase in the parameter than protocol 2 subjects. The same trend was observed also for COWR, but the difference between protocol groups was slightly smaller and the interaction protocol-by-time did not reach the statistical significance. Finally, treatment duration in protocol 1 was significantly lower than in protocol 2. Conclusion: The results of our study suggest that the new activation protocol would seem more effective as it allows to achieve the objective of the therapy more quickly, and likely leading to greater bodily expansion.

Dental parameter quantification with semi-automatized computational technology for the analysis of human bitemarks

ABSTRACT The study objective was to determine dental parameters that characterize human bitemarks and dentitions for biter identification using semi-automatized technology. Sixty-five dental casts and eighteen bitemark photographs were used. Casts were scanned by a 3D laser scanner to generate comparison overlays, and bitemarks were digitally photographed following ABFO guidelines. A semi-automatized technique was used to calculate the inter-canine distance, rotation, eccentricity, angular position, and distance to the arch of each tooth mark. A matrix was created of all possible combinations of dental casts and bitemarks. Receiver operating characteristic (ROC) curves were constructed to evaluate the accuracy of this identification procedure. Among the 1045 comparisons performed, the highest area under the ROC curve (AUC) was obtained for the Euclidean distance of lower teeth rotation (AUC = 0.73). This semi-automatized method to measure lower tooth rotation may be useful to identify individuals responsible for bitemarks and may be applicable in forensic cases.

Mandibular Canine Index as A Tool in Gender Identification - A Study in Malwa Population

Teeth are the hardest tissue in the body. Mandibular canines are important tooth in the human body which shows significant sexual dimorphism. Mandibular canine index can be used for gender identification during mass disasters and crime scenes. The purpose of this study was to investigate the accuracy with which gender can be differentiated in Malwa population by using the Mandibular Canine Index and sexual dimorphism. Materials and Method: The study sample includes 300 Mandibular casts of people residing in Malwa. It included 137 males and 163 female participants. Mesio distal diameter of mandibular canines were measured from mesial contact point to distal contact point of right and left mandibular canines. Inter canine distance was measured between tips of both canines. These were used for deriving MCI and determining sexual dimorphism exhibited by mandibular canines. Results: The mesiodistal width of mandibular canine were larger in males than in females. The mean difference of MCI between males and females were more on the left canine, thus making it highly significant (P Value&lt;0.001). The standard mandibular canine index for Malwa population was obtained as 0.262. Sexual dimorphism of right mandibular canine was estimated as 4.30% and for left mandibular canine was 5.58%. Sexual dimorphism of mandibular canine is more on left side. The overall percentage accuracy of sex prediction using standard mandibular canine was found to be 65.52%. Conclusion: Tooth remains obtained from crime scenes or disasters can be used for gender identification as this method is very simple, accurate and useful.

Transverse stability of Class II malocclusion correction with the pendulum appliance

This study aimed to evaluate the stability of transverse changes after Class II malocclusion correction with the pendulum fixed distalizer, followed by preadjusted edgewise fixed orthodontic appliances. This longitudinal study was conducted in the maxillary dental casts of 20 Class II malocclusion subjects (mean age, 12.5years; 14 females and 6 males). Eighty 3-dimensional maxillary dental casts were analyzed; 20 at the beginning of treatment, 20 after distalization, 20 after edgewise appliance debonding, and 20 at 5years posttreatment. Maxillary transverse distances between canines, first premolars, second premolars, first molars, and secondmolars were analyzed using GeomagicStudio 5 (3D Systems, Rock Hill, SC). There were no significant changes in intercanine distance during and after treatment. There were significant interfirst and intersecond premolar distance increases during treatment. There were significant interfirst and intersecond molar distance increases during the distalization phase. However, there were significant decreases in these distances at the end of treatment. There were no significant long-term posttreatment changes. The intercanine distance remains stable during and after treatment. The interfirst and intersecond premolar distances significantly increase during treatment and remain stable after treatment. The interfirst and intersecond molar distances increase during the distalization phase, decrease at the end of treatment, and remain stable after treatment.

Estimation of Different Facial Landmarks as a Guide in Intercanine Distance Determination (Clinical Study)

Aims:To evaluate the relationship between some of facial parameters including [(alae of nose, mouth, philtrum of upper lip) widths with interzygomatic distance] and straight maxillary intercanine distance for clinical application advantage. Materials and Methods: In this clinical study, (140) dental students in College of Dentistry/University of Mosul were examined and their facial and dental measurements were taken directly from each student by using an electronic digital vernier caliper. The data were collected and analyzed with computer to determine the correlation between the studied factors.Result: The results of this study demonstrated that all the measured parameters were larger in males than females which being statistically different between the two sexes and the Pearson Product Moment Correlation Coefficient test revealed that non of the facial parameters were measured had a significant correlation with straight maxillary intercanine cusp tips distance in females, while both of interzygomatic distance and philtrum width of upper lip had a significant correlation with straight maxillary intercanine cusp tips distance in males which they could be used to determine this distance for replacement of maxillary anterior teeth in males. Conclusion: Depending on previously mentioned results the straight maxillary intercanine distance was equal to interzygomatic distance divided by a factor of( 3.3), while multiplying the width of the philtrum of upper lip with a factor of ( 2.75) gives us an estimation of the straight maxillary intercanine cusp tips distance.

Assessment of dental arch stability after orthodontic treatment and oral rehabilitation in complete unilateral cleft lip and palate and non-clefts patients using 3D stereophotogrammetry

BackgroundAlthough arch stability has been studied in patients without a cleft, evidence for patients with a cleft is sparse. Therefore, we compared the dimensions and stability of dental arches in cleft lip and palate patients and those without a cleft.MethodsForty participants, 20 with a complete unilateral cleft lip and palate and 20 non-cleft patients aged from 18 to 30 years, with anterior and/or posterior crossbite and receiving orthodontic treatment were evaluated retrospectively. Eighty gypsum casts were digitized using a laser model scanner casts for both groups made immediately after the orthodontic treatment was completed (T1). Also, for the Cleft Lip and Palate group, casts were obtained and digitized 1 year after implant-supported rehabilitation (T2) and for the Non-Cleft Lip and Palate group, 1 year after the conclusion of the orthodontic treatment (T2). The formula: Δ = T2-T1 evaluated the stability of dental arches for inter-canine distances (C-C′), inter-molar distances (M-M’), arch length (I-M), palate surface and volume. The dimensions of the dental arches were measured digitally. The independent t test was used for statistical analysis (α = 0.05).ResultsA statistical difference was found in the stability of the groups for inter-canine (cleft area) measurement. At the times T1 and T2, a statistically significant difference was found in the arch length, surface and volume.ConclusionsThis study concluded that in the Cleft Lip and Palate group, the maxillary dimensions were not stabilized after 1 year of orthodontic and prosthodontic treatment (mainly for the inter-canine linear measurement) and that the transverse arch dimensions were smaller compared with those of non-cleft patients.

3D CBCT Analysis of Odontometric Variables for Gender Dimorphism in Saudi Arabian Subpopulation

Background: For assessing the sex of unidentified or skeletonized individuals, the tooth crown diameters are a good and reliable source amongst the other clinical markers. Aim and Objectives: To check the accuracy and reliability of Mandibular Canine Index (MCI) in sex determination among Saudi subpopulation using 3D Cone Beam Computerized Tomography (CBCT) images. An additional objective is to establish the norm of Standard MCI. Methodology: A total of 400 CBCT images were studied for the measurements of mesio-distal width (MDW) and inter-canine distance (ICD) of mandibular canines. Then, the observed and Standard MCI were calculated that was statistically determined by receiver operating characteristic (ROC) analysis. Results: Left canine showed greater sexual dimorphism. The Standard MCI was calculated as 0.239 (right mandibular canine) and 0.241 (left mandibular canine). The ability to determine gender correctly using Standard MCI (right mandibular canine) method was estimated to be 49% among males and 46.5% among females. The accuracy of the method, when applied to the combined data, was 47.8%. Conclusion: MCI and the variables that allow MCI quantification were shown to distinguish the groups, in terms of average, suggesting the possibility that canine-related measurements may be used for sex discrimination.

Palatoscopy and odontometrics' potential role in sex determination among an adult Egyptian population sample: A pilot study.

Background: Sex determination is the first step in personal identification in the forensic field. This study aimed to evaluate sexual dimorphism by using palatal rugae pattern and odontometrics, construct an Egyptian equation for sex determination using the discriminant function analysis. Participants and methods: The study sample included 200 participants of both sexes. Maxillary arch impressions were taken with alginate impression material using stainless steel impression tray. Identification and measurements were done to study the palatal rugae pattern, dental arch dimensions, and maxillary canine. Results: There was a highly statistically significant difference between males and females with higher male values regarding the total palatal rugae number, wavy rugae number, primary rugae number, arch length, width, maxillary canine right width, maxillary canine left width, intercanine distance, and maxillary canine right index while there was a highly statistically significant difference with higher female value regarding the straight rugae numbers. Four Egyptian equations were constructed using discriminant function analysis to determine the sex of an unidentified person. Conclusions: Palatal rugae pattern, dental arch dimensions, and maxillary canine index can be considered as useful tools for sex determination in the forensic field.

Comparison of changes in the dental transverse and sagittal planes between patients treated with self-ligating and with conventional brackets.

ABSTRACTIntroduction: Several advantages have been established regarding the efficiency of self-ligating brackets (SL). In spite of some controversy surrounding this question in the literature, clinical results confirm that “arch development” requires fewer extractions. Objective: The objective of this study was to compare changes in the transverse and sagittal planes in patients treated with conventional ligating brackets (CL)as well as in patients treated with SL brackets and oversized arches. Methods: A sample was selected from a pool of 300 consecutive cases treated by a single clinician: 51 patients with SL brackets and oversized wires, and 55 with CL brackets. These two groups were compared with a control group of 20 patients. All plaster models were scanned and dental landmarks were measured to identify changes from commencement (T0) to conclusion (T1) of treatment. Lateral cephalograms were analyzed for changes in the lower incisor (IMPA) and the first lower molar distal angulation (MAng). Intraoperator reliability was tested with linear regression analysis. To assure all groups were comparable at T0, an ANOVA test with a 95%confidence interval (CI) was performed for all values. To assess changes from T0 to T1 in all groups, a Student’s t-test with 95% CI was used. Finally, results from the three groups were compared using an ANOVA-test (95% CI) and a post-hoc test. Results: Increases in all the transverse variables were recorded in the two groups treated (SL and CL), except for the lower intercanine distance in the SL group. IMPA difference from T0 to T1 was higher in the CL group, and molar distal angulation (MAng) took place in the SL group. Conclusions: Self-ligating brackets with oversized arches and conventional ligating brackets showed increases in all variables in the transverse plane, except for the SL group at the mandibular intercanine distance. In comparison with the CL group, fewer different IMPA values were observed in the SL group, in which distal molar angulation occurred.

Implementation of Anthropometric Measurements in Anterior Teeth Selection in Two Ethnic Groups: An In Vivo Study.

ABSTRACTAim:The aim of this study was to evaluate whether there is any consistent relationship between interalar distance and six maxillary anterior teeth in two ethnic groups.Materials and Methods:Two hundred subjects (Assamese 100 and Nyishi 100) of different age and sex ranging from 18 to 33 years were identified for this study. The distance between two widest points marked on the alae of nose was measured by means of sliding digital caliper. Statistical analysis of variance was the testing method to determine whether the nasal width and intercanine distance were different in various racial groups.Results:The mean nasal width dimension in Assamese group was 36.38 mm (range 28.55–50.00 mm). The mean nasal width dimension in Nyishi group was 35.73 mm (range 31.34–41.90 mm). For the nasal width, no significant difference was observed between two races. For the canine cusp tip to cusp tip distance, the mean value of Assamese subjects was 43.63 mm (range 39.02–50.02 mm), whereas the Nyishi presented 41.77 mm (range 36.69–47.05 mm).Conclusion:For the two racial groups studied, the measurements of the interalar width showed a weak correlation with the canine to canine distance, not sufficiently high to be used as a predictive factor. It suggests to select wider artificial teeth. Practitioners can use ethnic norms as guides, not absolute values.

Satisfactory outcomes after orthognathic surgery with surgically assisted rapid maxillary expansion using a hybrid device.

The self-reported functional outcomes, clinical findings, and results of dental cast analysis before and after orthognathic surgery with surgically assisted rapid maxillary expansion (SARME) using a hybrid rapid maxillary expander (RME) were evaluated. Data were collected from 43 patients who underwent orthognathic surgery with SARME using a hybrid RME between 2001 and 2013. The patients were recruited during a follow-up clinical examination and were required to complete a questionnaire about their opinions and self-reported functional outcomes. Dental casts were used to analyze posttreatment palatal expansion. The mean follow-up time was 68 months (range: 25-135 months). The most common indication for SARME was the presence of a crossbite. Of the 30 patients who underwent a follow-up clinical examination (69.8% answer rate), 4 (13.3%) had symptoms of temporomandibular disorder (TMD), 1 (3.3%) experienced myalgia, and 3 (10.0%) experienced arthralgia on clinical palpation. Cast analysis revealed significant palatal expansion. The intercanine distance, intermolar distance, and palatal height were increased by 3, 5, and 2 mm, respectively. Overall, the patients were satisfied with the preoperative information, improved functions, and aesthetic results. The prevalence of TMD symptoms and other side effects following orthognathic surgery with SARME using a hybrid RME was low, and significant palatal expansions were achieved.

Maxillary expander with differential opening vs Hyrax expander: A randomized clinical trial

The aim of this 2-arm parallel trial was to compare the dentoskeletal effects of the expander with differential opening (EDO) and the Hyrax expander in the mixed dentition. Patients aged 7-11years with maxillary dental arch constriction and Class I or Class II sagittal relationships were randomly allocated into 2 study groups. The experimental group comprised 22 patients (10 males, 12 females) with a mean age of 8.46years treated with the EDO. The comparison group was composed of 24 patients (6 males, 18 females), mean age of 8.92years treated with the conventional Hyrax expander. One complete turn per day for 6days was performed for the posterior screw of the EDO and for the Hyrax expander. The anterior screw of the EDO was activated 1 complete turn per day for 10days. The primary outcomes were the anterior opening of the midpalatal suture, changes on the interincisal diastema width, maxillary dental arch widths, arch perimeter, arch length, palatal depth, inclination of maxillary posterior teeth and on dental arch shape, and the amount of differential expansion in the anterior region compared with the posterior region of the maxillary dental arch. Computer-generated randomization was used. Allocation was concealed with sequentially, numbered, sealed, and opaque envelopes. Blinding was applicable for outcome assessment only. Occlusal radiographs of the maxilla were obtained at the end of the active expansion phase (T2). Intraoral photographs were obtained immediately pre-expansion (T1) and at T2. Digital dental models were obtained at T1 and 6months after the active expansion period (T3). Intergroup comparisons of T1-T2 changes were performed using multiple linear regression analysis (P<0.05). The independent variables were both treatment and the starting forms. Bonferroni correction for multiple tests was applied. The experimental group showed a significantly greater opening of the anterior region of the midpalatal suture, a greater increase of the interincisal diastema width, and greater increases of the intercanine distance and inter-first deciduous molar distance than the Hyrax expander. The experimental group showed a significant differential expansion between the anterior and posterior regions, whereas the Hyrax group produced a similar expansion in the canine and molar regions. Serious harm was not observed. The EDO was capable of promoting greater orthopedic and dental changes in the anterior region of the maxilla than the conventional Hyrax expander. Similarity between the 2 expanders was observed for changes in the posterior region width, arch perimeter, arch length, palatal depth, and posterior teeth inclination.

Modern Surgery-First Approach Concept in Cleft-Orthognathic Surgery: A Comparative Cohort Study with 3D Quantitative Analysis of Surgical-Occlusion Setup.

Despite the evident benefits of the modern surgery-first orthognathic surgery approach (reduced treatment time, efficient tooth decompensation, and early improvement in facial esthetics), the challenge of the surgical-occlusion setup acts as a hindering factor for the widespread and global adoption of this therapeutic modality, especially for the management of cleft-skeletofacial deformity. This is the first study to assess three-dimensional (3D) quantitative data of the surgical-occlusion setup in surgery-first cleft-orthognathic surgery. This comparative retrospective study was performed on 3D image datasets from consecutive patients with skeletal Class III deformity who had a unilateral cleft lip/palate (cleft cohort, n = 44) or a noncleft dentofacial deformity (noncleft cohort, n = 22) and underwent 3D computer-assisted single-splint two-jaw surgery by a single multidisciplinary team between 2014 and 2018. They received conventional orthodontics-first or surgery-first approaches. 3D quantitative characterization (linear, angular, and positional measurements) of the final surgical-occlusion setup was performed and adopted for comparative analyses. In the cleft cohort, the occlusion setup in the surgery-first approach had a significantly (all p < 0.05) smaller number of anterior teeth contacts and larger incisor overjet compared to the conventional approach. Considering the surgery-first approach, the cleft cohort presented significantly (all p < 0.05) larger (canine lateral overjet parameter) and smaller (incisor overjet, maxillary intercanine distance, maxillary intermolar distance, ratio of intercanine distance, and ratio of intermolar distance parameters) values than the noncleft cohort. This study contributes to the literature by providing 3D quantitative data of the surgical-occlusion setup in surgery-first cleft-orthognathic surgery, and delivers information that may assist multidisciplinary teams to adopt the surgery-first concept to optimize cleft care.

Accuracy of Linear Measurements of Dental Models Scanned Through 3D Scanner and Cone-Beam Computed Tomography in Comparison with Plaster Models

Introduction and objective: Virtual surgical planning uses clinical data, image testing, plaster models of dental arches and clinical photos to simulate an orthognathic. There are two ways to perform the scanning of plaster models: scanning for cone-beam computed tomography (CBCT) or 3D scanner. The purpose of this study was to assess the accuracy and the degree of magnification of plaster model images obtained through 3D scanner and CBCT. Materials and methods: The control group was the measurement performed on 40 plaster models by Mitutoyo caliper. The same 40 models were scanned through 3D scanner and CBCT in order to compare the degree of distortion. The models were tested on the Dolphin software. Six measurements were performed in upper and lower arches: intermolar distance; intercanine distance; segment A; segment B; mesiodistal and cervico-incisal distance of the right-side central incisor. Results: There was no statistically significant difference for upper and lower models. However, CBCT had the degree of distortion of 2.34%, while the 3D scanner presented the degree of distortion of 2.37% comparing the degree of distortion of both methods with the digital caliper. Conclusions: It can be concluded that only the distances of segments A and B of the upper model were not compatible in both scanning methods with the measurements of digital caliper. However, considering all of the measurements, 3D scanner and CBCT are trustworthy to perform linear measurements on digital models and are sufficiently adequate for initial diagnosis and and are clinically acceptable in clinical dental practices.

Exploring the degrees of distortion in simulated human bite marks

The properties of the skin and the posture of the body during photographic recording are factors that cause distortion in the bite mark injury. This study aimed to explore the degree of distortion between a ‘touch mark’ (method 1) and a ‘bite mark’ (method 2) on the left upper arm at three different positions (arm relaxed; arm flexed in two different positions). A pair of dental casts with biting edges coated in ink was used to create a mark in 30 subjects (6 ♂, 24 ♀) aged 20–50 years old. Photographs were taken using a Nikon DX digital camera (D5000). The mesiodistal widths and angle of rotations of both upper right central incisor and lower right central incisor and the inter-canine distances were analysed and compared with the true measurements using Adobe Photoshop CC 2017. Statistical analysis was carried out using SPSS Statistics 22 applying a 2 (mark type) × 3 (position) repeated measures ANOVA. For all measures studied, there was a statistically significant difference between mark types and positions. In the case of bite marks, a great degree of distortion was detected, and this increased further when changing the position of the arm. The findings demonstrated that skin properties and posture influence distortion. This could lead to inaccurate measurements and misleading pattern interpretation of bite mark injuries.

Twenty-year follow-up of functional treatment with a bionator appliance: A retrospective dental cast analysis.

To investigate changes in dental arch configuration, relationship, and malocclusion directly after Class II malocclusion treatment with a Balters bionator modified by Ascher as well as 20 years after treatment. Orthodontic dental cast analysis of 18 patients with skeletal Class II treated with a bionator without any additional fixed therapy was performed with a digital caliper at three stages: before (T0), after (T1) and 20 years after (T2) treatment. Arch perimeter and depth, intermolar and intercanine distance, overjet, overbite, sagittal molar and canine relationship, mandibular incisor irregularity (Little's index), and malocclusion (PAR index) were assessed. During treatment (T0-T1), upper arch perimeter significantly increased with a significant decrease in the upper and lower arch perimeter long-term (T1-T2), whereas corresponding arch depths changed only slightly in both periods. Transverse intermolar width increased significantly during treatment, remaining almost constant from T1 to T2. Lower intercanine distance remained fairly unchanged during treatment, but decreased significantly during follow-up. Lower incisor irregularity improved slightly during treatment but increased significantly long-term. After treatment, sagittal molar relationships on both sides were improved, overjet and overbite reduced; these significant changes remained stable long-term. The peer assessment rating (PAR) index was significantly lower after treatment and increased insignificantly during follow-up. 20 years after bionator treatment without additional fixed appliances, the improved sagittal relationship and the reduced overjet and PAR index remained fairly stable. Long-term changes are most likely due to physiological aging processes and are not associated with bionator treatment.

Variation of upper lip pressure on upper teeth during non-extraction orthodontic treatment: A prospective clinical study

The objectives of this prospective clinical study are to quantify the variation of pressure exerted by the upper lip on the upper teeth during the alignment phase and to evaluate its capacity to adapt to changes in dental position. Thirty young subjects in skeletal Class I relationship requiring non-extraction orthodontic treatment were included in this study. The pressure exerted by the upper lip on the upper central incisors and right canine were measured during rest and swallowing positions using a pressure transducer before bracket placement (T0), after bracket placement (T1), three months (T2) and six months later (T3). Maxillary intercanine width (CC), upper arch length (U) and crowding (C) were measured on stone models at T1, T2and T3to determine the existence of a correlation between the variation of lip pressure and these variables. The lip pressure significantly increased after bracket placement and remained relatively stable during the six-month period. The labial pressure on the incisors was the only variable to significantly decrease at T3, though remaining significantly higher than the starting pressure. A positive correlation was found between the variation of the inter-canine distance and the labial pressure on the canine at rest whereas a negative correlation exists between the crowding and the labial pressure on the incisors at rest. This study showed that increasing inter-canine width disrupts the muscle equilibrium and therefore is prone to relapse, whereas the upper lip can better adapt to the protrusion of upper incisors.

Obstructive sleep apnea severity and dental arches dimensions in children with late primary dentition: An observational study

ABSTRACT Objective: The aim of this study was to compare the dimensions of the upper and lower arches in children affected by OSAS with different levels of severity of obstruction. Methods: Twenty-seven Caucasian children (14 males, 13 females; mean age 6, range 5.2–6.1 years) with a diagnosis of OSAS determined by polysomnography were enrolled in this study. The dimensions of both dental arches were measured, and the data were compared among children affected by severe, moderate, and mild OSAS. Results: Statistically significant differences among the three groups revealed that children with severe OSAS had the highest values of upper intercanine and intermolar distances in the sample. Discussion: A severe OSAS grade (AHI > 10) is associated with statistically significantly higher upper intercanine and intermolar distances compared with mild and moderate grades. An early approach to OSAS in children with late primary dentition is auspicated in order to prevent an influence on dental arches growth.