Oro-facial function and quality of life in children and adolescents with large horizontal maxillary overjet-A case-control study.

BACKGROUND: Large horizontal maxillary overjet (overjet) is associated with reduced bite force (BF) and number of contacts, which influence the chewing effectivity (CE). Oral health, oro-facial function (OF) and malocclusion have great impact on psychological well-being and quality of life (QoL). OBJECTIVES: The aims of the study were to examine OF, temporomandibular disorders (TMD), BF, CE, QoL and well-being in children and adolescents with large overjet. METHODS: The study was a case-control study including healthy children with large overjet in the study group compared to a control group of healthy children with neutral occlusion, all 9-14 years old. OF was examined by use of Nordic Orofacial Test-Screening (NOT-S), Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and registration of morphological and functional occlusion. QoL and well-being were examined using KIDSCREEN-10 and Strengths and Difficulties Questionnaire. RESULTS: The study and control groups included 37 and 32 participants, respectively. Significantly increased NOT-S score (p < .001) and reduced BF (p = .011), numbers of contacts (p < .001) and CE (p = .005) were found in the study group. BF, numbers of contacts and CE were negatively associated with erupting canines and premolars. No significant difference was found in age, gender, dental eruption, TMD diagnosis or QoL between the groups. Significantly increased emotional symptoms (p = .007), hyperactivity (p = .043) and total difficulties score (p = .009) were found in the study group. CONCLUSION: The study group showed higher NOT-S score and reduced BF, number of contacts and CE. No difference in QoL were found between the groups, although reduced well-being and increased emotional symptoms, hyperactivity and total difficulties were found in the study group.

Occlusal traits of 4-5-year-old Estonians. Parents' perception of orthodontic treatment need and satisfaction with dental appearance.

This study aims to evaluate the prevalence of occlusal traits and to assess parents'/caregivers' satisfaction with child's dental appearance and perception of orthodontic treatment need in 4-5-year-old Estonians. Clinical records and plaster casts of 390 children (190 girls and 200 boys, mean age 4.7 years, range 4 - 5 years) were analyzed. Assessed occlusal traits included deciduous canine and second molar sagittal relationship, overjet, overbite, crowding, midline diastema, crossbite, and scissor bite. Parents'/caregivers' opinions regarding their child's teeth were determined with a questionnaire. The most prevalent occlusal traits were symmetrical sagittal relationship in deciduous canines (78.2%) and molars (75.1%), Class I sagittal relationship in deciduous canines (69.7%) and midline diastema (67.7%). Asymmetrical sagittal canine relationship was registered in 21.8% deciduous canines and in 24.9% second deciduous molars. Parents'/caregivers' perceived orthodontic treatment need was related to Class III sagittal relationship in canines, increased overjet and overbite, negative overbite, and crossbite. Prevalence of most occlusal traits in Estonian children were in line with those reported in neighboring countries. Parents/caregivers were well able to observe occlusal traits that deviated from acceptable occlusion.

Reliability of mandibular movement assessments depending on TMD.

OBJECTIVE: This study determines the effect of temporomandibular disorders (TMD) on the reliability of mandibular movement assessments. METHODS: The vertical and horizontal jaw movements, as well as overjet and overbite, were measured twice in 56 consecutively recruited adult subjects with TMD according to the RDC/TMD and 29 controls without TMD diagnosis by experienced dentists utilizing a millimeter ruler. The reliability was determined by intraclass correlation coefficient (ICC). RESULTS: Neither statistically nor clinically relevant differences in the repeatability between both subgroups could be detected (all p ≥ 0.077). The mouth opening and overjet proved an excellent reliability (ICC 0.85-0.92). Overbite and laterotrusion showed good to excellent reliable results (ICC 0.74-0.82). The second measurement of the vertical jaw movement resulted in systematically higher values (p < 0.003). DISCUSSION: The assessment of the mandibular movement with a millimeter ruler is a reliable procedure irrespective of TMD. To decrease the variances in the mouth opening measurements, the patient should be asked beforehand to practice this movement.

Changes in lips, cheeks and tongue pressures after upper incisor protrusion in Class II division 2 malocclusion: a prospective study.

BACKGROUND: The etiology of Class II division 2 (CII/2) malocclusion focuses on heredity; however lip, cheek, and tongue pressures that are associated with the environmental effect are considered to have an effect. The aim of this study was to evaluate the relation between perioral pressures and the upper incisor inclination in CII/2 malocclusion. METHODS: Twenty patients (8 females, 12 males; mean age 10.29 ± 0.90 years) with CII/2 malocclusion were included in the study group, and 15 patients (5 females, 10 males; mean age 10.56 ± 1.06 years) with Class I malocclusion were included. The upper incisors were protruded with a utility arch (0.016 × 0.022 in. blue elgiloy wire). Perioral pressure assessment was made with the Iowa Oral Pressure Instrument. Upper lip pressure, lower lip pressure, vertical lip pressure, left-right buccal pressures, swallowing, and maximum tongue pressures were measured. Repeated measure ANOVA was used to test the intragroup differences. Intergroup comparisons were made using two-way repeated measure ANOVA with Bonferroni correction. Relationships between the variables were analyzed using rank correlation (Spearman's rho). The significance for all statistical tests was predetermined at p < 0.05. RESULTS: A significant change occurred in the upper lip pressure, lower lip pressure, and vertical lip pressure; however, significant difference was not found between the groups. Upper lip pressure increased significantly in both groups. In the CII/2 group, lower lip pressure increased after protrusion and decreased after retention, while vertical lip pressure decreased and then increased significantly. Left buccal pressure changes between the groups were not parallel. Right buccal pressure, swallowing, and maximum tongue pressure changes were not statistically significant. Statistically significant correlation was found between U1-NA (mm) and vertical lip pressure (r -0.467). CONCLUSIONS: In the CII/2 group, upper lip pressure increased only in retention. Lower lip pressure increased and vertical lip pressure decreased after protrusion. Nevertheless, these changes did not remain stable after the retention period. The difference between groups was not statistically significant at the end of retention.

Effect of a thin-neck pacifier on primary dentition: a randomized controlled trial.

OBJECTIVES: To evaluate changes in occlusal characteristics in the primary dentition that occur after introducing a thin-neck pacifier (TNP) to children with previously diagnosed pacifier-associated anterior open bite (AOB) and increased overjet. SETTING AND SAMPLE POPULATION: Department of Preventive and Pediatric Dentistry, Jena University Hospital, Germany. Subjects were 86 children (mean age 20.3 months) with a pacifier-associated open bite or overjet ≥2 mm. MATERIAL & METHODS: Randomized controlled trial. Subjects were randomly assigned: group I (n = 28), intervention group using a TNP; group II (n = 30), control group, using a conventional or physiological pacifier; and group III (n = 28), intervention group, Gold standard, weaned off pacifier. Participants were re-examined after 3, 6, 9 and 12 months by an operator, blinded for the treatment. RESULTS: After 12 months data for 63 children (mean age 33.1 months) were analyzed (I: n = 24; II: n = 22; III: n = 17). There was a significant difference between the groups regarding mean overjet (group I: 2.7 ± 0.5 mm, group II: 3.2 ± 0.7 mm, group III: 2.4 ± 0.5 mm, Kruskal-Wallis, p = 0.002) and AOB (group I: -1.2 ± 0.3 mm, group II: -2.2 ± 0.3 mm, group III: -0.8 ± 0.8 mm, Kruskal-Wallis, p < 0.001). The differences between group I and II regarding increased overjet (3.1 ± 0.2 mm vs. 3.6 ± 0.3 mm, Mann-Whitney, p < 0.001) and extent of AOB (-1.2 ± 0.3 mm vs. -2.2 ± 0.3 mm, Mann-Whitney, p < 0.001) were statistically significant. CONCLUSION: Use of TNP resulted in better clinical measurements for in overjet and overbite compared with the continuing use of conventional or physiological pacifiers.

Effect of malocclusion severity on oral health-related quality of life and food intake ability in a Korean population.

INTRODUCTION: The aim of this study was to evaluate the effect of malocclusion severity on oral health-related quality of life and food intake ability in adult patients, controlling for sex, age, and the type of dental clinic visited. METHODS: The sample consisted of 472 Korean patients (156 male, 316 female) with a mean age of 21.1 (SD, 8.6) years in a dental hospital and a private clinic. The correlations between the Korean version of the Oral Health Impact Profile-14 (OHIP-14K), subjective food intake ability (FIA) for 5 key foods, and Index of Orthodontic Treatment Need-Dental Health Component (IOTN-DHC) were investigated. RESULTS: The mean IOTN-DHC and OHIP-14K scores were significantly higher for the dental hospital patients than for the private clinic patients (IOTN-DHC, P <0.001; OHIP-14K, P <0.05). Malocclusion severity was significantly higher in male than in female subjects (P <0.001). Older patients perceived their oral health-related quality of life more negatively than did the teens (P <0.001). As the severity of the malocclusion increased, oral health-related quality of life and masticatory function worsened (OHIP-14K, P <0.001; FIA, P <0.05). CONCLUSIONS: As the severity of the malocclusion and the age of the patients increased, oral health-related quality of life and masticatory function relatively deteriorated. This finding provides evidence that severe malocclusions are associated with lower quality of life and less masticatory efficiency in older patients.

Anatomical characteristics of catathrenia (nocturnal groaning) in upper airway and orofacial structures.

BACKGROUND: Catathrenia is a rare sleep disorder characterized by repeated groaning in a protracted expiration preceded by a deep inspiration. This study aimed to explore whether anatomy is one of pathophysiology of catathrenia by investigating the anatomical features associated with catathrenia in the upper airway, craniofacial structures, and dental patterns. MATERIAL AND METHODS: Twenty-two patients with catathrenia (7 males, 15 females; age 22 to 69 years) were recruited as well as 66 patients matched by age and gender (matching proportion 1:3) with obstructive sleep apnea syndrome (OSAS). Both groups underwent cephalograms and dental casting, and cephalometric measurements and the Peer Assessment Rating (PAR) index was applied. Differences between the two groups were evaluated and cephalometric measurements in catathrenia group were compared with control values of Chinese patients from previous studies. RESULTS: As for airway-related measurements, increased PNS-R, PNS-UPW, and H-FH and decreased SPT and TGL were found in catathrenia group compared to normal values. Such trends were found even more evident when compared with the OSAS Group. As for craniofacial parameters, values of U1/NA and U1/SN were found increased in the catathrenia group compared with normal values and values of MP/FH and Y decreased. The differences were more distinct from the OSAS Group. Increased arch lengths and upper inter-first molar widths, and decreased overbite and PAR index, were found in catathrenia group compared with the OSAS Group. CONCLUSION: Catathrenia patients present with a broad upper airway, yet protrusive upper incisors and flat mandibular angles. Anatomical characteristics of catathrenia are different from those associated with OSAS, namely a wide airway, large skeleton, and good occlusion.

The relationship between craniofacial development and hypodontia in patients with Down syndrome.

BACKGROUND/OBJECTIVE: Hypodontia is often seen in people with Down syndrome (DS). In the normal population, persons with hypodontia have a shorter cranial base and a hypoplastic maxilla, leading to a skeletal Class III tendency and a reduced face height. The purpose of this study was to examine craniofacial morphology in patients with DS at different ages and the influence of hypodontia on their craniofacial morphology. MATERIALS AND METHODS: A comparative cross-sectional study was conducted in 63 children with DS (6-19 years old; 28 males and 35 females) at a Centre for Special Care Dentistry in Rotterdam, the Netherlands (CBT Rijnmond). Digital lateral cephalograms were obtained from all subjects and a cephalometric analysis was performed. The subjects were divided into a group with hypodontia (13 males and 25 females) and a group without hypodontia (15 males and 10 females). RESULTS: Significant results included a decrease in antero-posterior relationship of upper and lower jaw (ANB angle -0.331° per year, P = 0.044) and a decrease in vertical dimension (S-N_Go-Gn angle -0.72° per year, P = 0.039) over the years in subjects with hypodontia compared to subjects without hypodontia. CONCLUSION: The process of growth in DS patients is towards a reversed overjet. Hypodontia seems to have an additional effect on this development. The management of hypodontia as part of the complete treatment of dental development in DS children is important because it strongly influences the jaw relationship.

Comparison of craniofacial growth of untreated Class I and Class II girls from ages 9 to 18 years: a longitudinal study.

INTRODUCTION: The purposes of this study were to examine and compare the craniofacial growth in girls with Class I or Class II occlusion from the ages of 9 to 18. METHODS: Twenty-five Class I (ANB, 1°-4°) and 21 Class II (ANB, >4°) untreated Caucasian girls were selected from the Burlington Growth Centre in Toronto, Ontario, Canada. Cephalograms of each subject at ages 9, 14, and 18 years were traced, and 29 parameters were measured. The growth changes in each parameter from ages 9 to 14, 14 to 18, and 9 to 18 were calculated, and comparisons of each parameter were made between the 2 groups. RESULTS: From ages 9 to 14, the Class I and Class II groups had similar skeletal growth patterns (increases of SNA and SNB angles, decreases of ANB, MP-SN, and gonial angles). Dentally, the Class II group showed less maxillary incisal proclination and more overbite than did the Class I group. From ages 14 to 18, the 2 groups also showed similar growth patterns, with little sagittal but continued vertical growth, and the MP-SN angle continued to decrease. From ages 9 to 18 (combined periods of 9-14 and 14-18), the 2 groups showed similar skeletal growth, with the exception of a slightly higher ANS-ME/N-Me in the Class I group. Dental changes were similar in the 2 groups, except that overbite increased slightly more in the Class II group. CONCLUSIONS: Overall, the craniofacial growth patterns of Class I and Class II girls were similar. With growth, the face became more flattened with a decrease of the ANB angle, and the mandible demonstrated forward rotation with decreases of the MP-SN and gonial angles, and an increase of PFH:AFH.

Analysis of association between posterior crossbite, median line deviation and facial asymmetry / Análisis de la asociación entre mordida cruzada posterior, desviación de la línea mediana y asimetría facial

Facial asymmetry is a common human characteristic and can occur on many levels, originate of genetic factors, and can be caused by traumas or due to cross bite and/or muscular disability. The aim of this study was to evaluate the relation between posterior crossbite, median line deviation and facial asymmetry. For this study 70 children aged between 3 and 10 years-old were examined and photographed. Using Microsoft Office Power Point 2007, horizontal lines and one vertical line on median line were drawn, to subjectively analyze facial discrepancies. In relation to overjet, the majority of children (78.6%) showed normal relation, followed by high overjet (17.1%), anterior crossbite (4.3%). In relation to overbite, the majority of children (60%) showed normal relation, 27.1% anterior opened bite (negative overbite), and 12.9% showed high overbite. Posterior crossbite was present in 27.1% of children. Among them, 68.4% showed unilateral crossbite on right side, 21.1% bilateral crossbite and 10.5% unilateral crossbite on left side. The relation between posterior crossbite and facial asymmetry, according to Fisher´s Exact Test (p=0.0970), there was no statistically significant association. In relation to median line, the association was statistically significant with posterior crossbite (p=0.0109) and with facial asymmetry (p=0.0310). There was association between posterior crossbite and median line deviation. There was no association between posterior crossbite and facial asymmetry

La asimetría facial es una característica humana común que puede ocurrir en diferentes niveles, originarse por factores genéticos, ser causada por traumas o mordida cruzada como resultado o discapacidad muscular. El objetivo de este estudio fue evaluar la relación entre la mordida cruzada posterior, desviación de la línea mediana y asimetría facial. Fueron evaluados 70 niños entre 3 y 10 años de edad mediante examen clínico y fotográfico. Utilizando Microsoft Power Point Office 2007, se dibujaron líneas horizontales y una línea vertical en la línea mediana, para analizar subjetivamente las diferencias faciales. En relación con el resalte, la mayoría de los niños (78,6%) mostró relación normal, seguido por un resalte aumentado (17,1%) y mordida cruzada anterior (4,3%). En relación con la sobremordida, la mayoría de los niños (60%) mostró relación normal, 27,1% una mordida abierta anterior (sobremordida negativa) y 12,9% mostró una sobremordida aumentada. La mordida cruzada posterior estuvo presente en 27,1% de los niños. Entre ellos, el 68,4% presentaba mordida cruzada unilateral del lado derecho, 21,1% mordida cruzada bilateral y el 10,5% mordida cruzada unilateral en el lado izquierdo. No hubo asociación estadísticamente significativa entre la mordida cruzada posterior y asimetría facial según la prueba exacta de Fisher (p=0,0970). En relación a la línea mediana, se observo una asociación estadísticamente significativa entre mordida cruzada posterior (p = 0,0109) y asimetría facial (p=0,0310). Existe asociación entre la mordida cruzada posterior y la desviación de línea mediana. No hubo asociación entre la mordida cruzada posterior y asimetría facial

Electromyographic evaluation of masticatory muscles at rest and maximal intercuspal positions of the mandible in children with sleep bruxism.

UNLABELLED: In adults, sleep bruxism (SB) may be related to reports of pain or fatigue in the muscles of mastication, resulting from multiple muscle contractions that occur during the night. In children, little is known about the consequences of this parafunction. PURPOSE: The objective was to compare the electromyographic activity (EMG) of the masseter and anterior portion of the temporalis muscles in children with and without SB; acquisitions were made at rest (RE) and in maximal intercuspal (MI) positions of the mandible. METHODS: Twenty children with signs and symptoms of SB (mean age 7.20 years ± 0.52) and 20 controls without signs or symptoms of SB (mean age 7.40 years ± 0.50) were selected. The controls were matched to the type of occlusal morphology evaluated according to Björk et al. (Acta Odontol Scand 22:27-40, 1964). Muscle activity was measured with the mandible at RE, MI and maximal clenching with cotton roll (MC), on the left and right sides. Data from the RE and MI (mV) were normalized by calculating them as % MC. The results were analyzed by descriptive statistics, Shapiro-Wilk test, Wilcoxon and Mann-Whitney tests. RESULTS: The subjects' age did not differ significantly between groups. EMG of temporalis muscle at RE differed between the right and left sides in both groups. There was no significant difference in EMG of masseter and temporalis muscles between groups. CONCLUSION: Children with SB showed no significant difference in EMG of masticatory muscles at RE and in MI positions of the mandible when compared with the control group.

Jaw clenching effects in relation to two extreme occlusal features: patterns of diagnoses in a TMD patient population.

OBJECTIVE: The aim of this investigation was to compare the pattern of temporomandibular disorder (TMD) diagnoses in clenching patients with different occlusal features, the null hypothesis being that no between-group differences exist. MATERIALS AND METHODS: Two groups of subjects receiving a jaw clenching diagnosis and having large overjet or anterior open bite (Group A; N=45, 75.5% females, mean age: 38.1 +/- 15.9 years) or normal occlusion (Group B; N=69, 71% females, mean age: 34.6 +/- 13.8 years) were recruited among a TMD patient population and were given Research Diagnostic Criteria for TMD (RDC/TMD) axis I diagnoses, namely, group I muscle disorders, group II disc displacements, and group III arthralgia/osteoarthritis/osteoarthrosis. MAJOR FINDINGS: The distribution of RDC/TMD single and combined group diagnoses was significantly different between the two groups (P<0.05), with Group A subjects showing a higher prevalence of multiple diagnoses (60% versus 43.3%), as well as a higher prevalence of combined RDC/TMD axis I group II and III diagnoses (37.8% versus 20.2%). All TMD signs and symptoms were more frequent in the patients with large overjet or anterior open bite with respect to the patients with normal occlusion. CONCLUSION: In a TMD patient population, jaw clenching may have different consequences in subjects with large overjet or anterior open bite with respect to subjects featuring normal occlusion.

Relationship between orofacial function, dentofacial morphology, and bite force in young subjects.

OBJECTIVE: The aim was to evaluate the relationship between orofacial function, dentofacial morphology, and bite force in young subjects. SUBJECTS AND METHODS: Three hundred and sixteen subjects were divided according to dentition stage (early, intermediate, and late mixed and permanent dentition). Orofacial function was screened using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need, bite force, lateral and frontal craniofacial dimensions and presence of sleep bruxism were also assessed. The results were submitted to descriptive statistics, normality and correlation tests, analysis of variance, and multiple linear regression to test the relationship between NOT-S scores and the studied independent variables. RESULTS: The variance of NOT-S scores between groups was not significant. The evaluation of the variables that significantly contributed to NOT-S scores variation showed that age and presence of bruxism related to higher NOT-S total scores, while the increase in overbite measurement and presence of closed lip posture related to lower scores. Bite force did not show a significant relationship with scores of orofacial dysfunction. No significant correlations between craniofacial dimensions and NOT-S scores were observed. CONCLUSION: Age and sleep bruxism were related to higher NOT-S scores, while the increase in overbite measurement and closed lip posture contributed to lower scores of orofacial dysfunction.

Orthodontic-surgical treatment: neuromuscular evaluation in open and deep skeletal bite patients.

BACKGROUND: The aim of this study was to compare electromyographic data of two groups of patients (open and deep skeletal bite) before and after surgical orthodontic treatment. METHODS: All patients who underwent orthognathic surgery at the Department of Orthodontics (University of Milan) were subjected to periodic electromyographic evaluation of the masticatory muscles (masseter and anterior temporal muscles) and to electrokinesiographic evaluation of mandibular movements. The sample comprised 72 patients (35 open skeletal bite patients and 37 deep skeletal bite patients) at the end of craniofacial growth. The electromyographic instruments used in the study included a Freely and a K6-I electromyograph. Statistical evaluation was carried out with Student's t tests for independent samples. RESULTS: Lots of differences between open and deep skeletal bite patients have been underlined by the analysis of the electromyographic data obtained. These results have been obtained with both electromyographic systems. Muscular activity in microvolts is higher in deep skeletal bite patients at the beginning of the treatment than in open bite ones, but during the following phases of the treatment, the two values became similar. CONCLUSIONS: Morphologic differences between open and deep bite patients can also be demonstrated by instrumental examinations, and their correction after surgical treatment is observable on electromyographic and electrognatographic exams.

Deep bite: a case report with chewing pattern and electromyographic activity before and after therapy with function generating bite.

AIM: The purpose of this case report is the concurrent evaluation of the masticatory pattern and the electromyographic activity, recorded during mastication, before and after therapy of deep bite malocclusion. CASE REPORT: An 11-year-old boy, affected by deep bite (overbite = 5 mm) was treated by the use of a functional appliance (Function Generating Bite for Deep bite correction = FGB-D). Mandibular movements during mastication of a soft and a hard bolus were recorded both before and 10 months after correction of the malocclusion. Electromyographic activity (EMG) of the masseters and anterior temporalis muscles were recorded at the same time. Chewing cycles and EMG activity were recorded with the K7 I kinesiograph (Myotronics Inc., Seattle, WA-USA). Before therapy a higher EMG activity was recorded for both masseters and anterior temporalis muscles in comparison with the results after therapy. RESULTS: The results showed a great decrease of the EMG activity of masseter and anterior temporalis muscles. Moreover, the height and width of the chewing cycles in the frontal plane increased after therapy. CONCLUSION: The functional improvement showed after therapy with FGB-D showed that the functional appliance is able to correct the dental malocclusion and the masticatory function. The orthodontic treatment should consider not only the repositioning of teeth within the dental arches but also the effects on function, especially when the malocclusion involves the muscular and skeletal structures.

Patterns of vertical facial growth in Korean adolescents analyzed with mixed-effects regression analysis.

INTRODUCTION: To understand the growth patterns of skeletal open bite and deepbite, we present observations from 9 years of pure longitudinal data based on lateral cephalometric radiographs using mixed-effects regression model analysis. METHODS: In total, 51 children (14 years old) with extreme values for the ratio of lower anterior facial height to total anterior facial height were assigned to 1 of 2 groups: a skeletal open-bite group (11 boys, 14 girls) or a skeletal deepbite group (14 boys, 12 girls). Measurements of total anterior facial height, upper anterior facial height, lower anterior facial height, total posterior facial height, ramus height, and ratio of lower anterior facial height to total anterior facial height were obtained for all subjects. All data were analyzed and interpreted using a mixed-effects regression model analysis with random effects. RESULTS: From these 4 groups at 14 years old, statistically significant differences were observed between the groups when subjects of the same sex were compared; however, statistical significance was not reached between subjects of opposite sexes in each group. Morphologic differences were clearly evident from the start and became more pronounced with age. There were statistical significances in the initial values and increases with age in all 6 variables except for increases with age in the ratio of lower anterior facial height to total anterior facial height. Statistical significance was also reached for morphologic differences between the annual increases in the ratio of lower anterior facial height to total anterior facial height and lower anterior facial height. In general, individual random variability was high in all variables when compared with the annual changes over time. CONCLUSIONS: Divergent patterns were established early and became more pronounced with age, with anterior facial height dimensions primarily contributing to these differences. Individual variations were so pronounced that caution is recommended for all clinical decisions.

Evaluation of the closest speaking space in different dental and skeletal occlusions.

STATEMENT OF PROBLEM: The closest speaking space (CSS) together with the vertical overlap of anterior teeth during the production of the /s/ sound have not been previously investigated with respect to differences in dental and skeletal orthodontic classifications. PURPOSE: The purpose of this study was to investigate the CSS in dental and skeletal occlusions and to analyze the cause and effect relationship of the CSS and the amount of the vertical overlap of anterior teeth. MATERIAL AND METHODS: Poly vinylsiloxane interocclusal registration material was placed bilaterally onto the occlusal surfaces of premolar and molar teeth of 155 native Turkish speaking adolescent and young adult dentate participants, who were then asked to pronounce the word seyis. The thinnest point between the maxillary and mandibular teeth was recorded in millimeters as the CSS. The occlusion of each participant was classified according to the Angle dental and Steiner skeletal classifications. The differences in CSS values within each classification were statistically analyzed with the Kruskal-Wallis test, and the correlation between the CSS and the vertical overlap was statistically analyzed with the Spearman Rho Correlation tests (P<.05). RESULTS: The differences in the CSS were only significant between Angle Class II division 2 and Class III groups (P=.034), while the differences in the CSS between skeletal classes were not significant. The correlation between the amount of CSS and the amount of vertical overlap was not significant. CONCLUSIONS: The results showed that regardless of dental and skeletal occlusions, average CSS values could be used to determine the occlusal vertical dimension of prosthetic restorations.

Bite force and its association with stability following Class II/1 functional appliance treatment.

The aims of this study were to investigate the value of pre-treatment maximal molar bite force as a predictive variable in determining post-treatment changes and stability following functional appliance treatment in Class II malocclusion children. Twenty-eight Class II malocclusion children having undergone functional appliance treatment were followed for at least 1 year post-treatment. Maximal molar bite force measurements, lateral cephalograms, and study casts were taken before treatment, after treatment, and after post-treatment follow-up. Relationships between pre-treatment maximal molar bite force and dental or cephalometric changes post-treatment were examined. Patients were divided into stable and unstable groups, based on dental sagittal changes (overjet and molar relationship), and differences between the two groups of patients determined. Post-treatment changes varied widely. Thirteen children showed dentoalveolar sagittal relapse, namely a shift in molars towards a Class II relationship and an increase in overjet, while 15 did not. The unstable group demonstrated a lower pre-treatment maximal molar bite force, as well as a more obtuse gonial angle, than the stable group. The gonial angle was found to be negatively correlated to maximal molar bite force and may thus be a cephalometric indicator partly reflecting the functional condition of the masticatory muscles. Children with a lower pre-treatment maximal molar bite force were more prone to dentoalveolar sagittal relapse following functional appliance treatment.

Dentofacial and upper airway characteristics of mild and severe class II division 1 subjects.

The aim of this retrospective, cross-sectional study was to assess whether mild and severe Class II division 1 subjects have craniofacial and upper airway characteristics, which relate to the severity of Class II as judged by overjet or ANB angle. The sample consisted of pre-treatment lateral cephalograms and dental casts of 131 males and 115 females (mean age 10.4 ± 1.6). Inclusion criteria were: healthy Caucasian subjects, at least ¾ Class II first molar relationship on both sides and overjet ≥ 4 mm. The cephalograms were traced and digitized. Distances and angular values were computed. Mild and severe Class II was defined by overjet (<10 mm/≥ 10 mm) or by ANB angle (<7 degrees/≥7 degrees). Statistics were performed with two-sample t-test and Pearson's correlation analysis. In the two overjet groups, significant differences were mainly found for incisor inclination while the two ANB groups differed significantly in SNA, WITS, Go-Pg, SpaSpp/MGo, SN/MGo, and Ar-Gn. The shortest airway distance between the soft palate and the posterior pharyngeal wall was significantly correlated to the NS/Ar angle. Statistical analysis revealed several significant correlations. Patients with a large overjet or ANB angle differed significantly from patients with a small overjet or ANB angle mainly in their incisor inclination. In the present sample, the overjet and to some extent also the ANB angle is determined by soft tissue or individual tooth position rather than by skeletal background. In retrognathic patients, a tendency towards smaller airway dimensions was found. However, statistical analysis did not reveal a strong connection between upper airway and dentoskeletal parameters, but a large interindividual variation.

A 40 years follow-up of dental arch dimensions and incisor irregularity in adults.

Dentoalveolar changes in adulthood have not been extensively documented. Such changes may have important implications for the long-term stability of orthodontic treatment. To analyse occlusal and dentoalveolar changes in adults from the age of 20 years to the age of 60 years. The material comprised 18 Swedish dentists, 16 men and 2 women, with no missing teeth and no prosthodontic or orthodontic treatment. Measurements were recorded on study casts made between 1949 and 1989 at the Department of Stomatognathic Physiology at the Faculty of Odontology in Malmö, thus documenting changes over an average period of 38.4 years. Malocclusion traits, overbite, overjet, dental arch length and width, and Little's irregularity index were registered. There was a significant increase in Little's irregularity index in the mandible (1.0 mm, P < 0.01) and a decrease in arch length in both jaws (0.5-0.9 mm, P < 0.05). The maxillary and mandibular intercanine widths decreased by 0.8 and 1.0 mm, respectively (P < 0.001). The malocclusion traits, overbite, and overjet remained unchanged during the observation period. The results confirm that dentoalveolar changes occur as a continuous process throughout adult life. The findings of potential clinical importance are decreases in arch length and depth, resulting in a decrease in intercanine width and an increase in anterior crowding. In clinical orthodontic practice, these findings have important implications for treatment planning and long-term stability after orthodontic treatment.