Fourier-transform infrared study on effects of ageing, oestrogen level and altered dietary loading on rat mandibular condylar cartilage.

OBJECTIVE: Mandibular condylar cartilage (MCC) of the rat was examined with the Fourier-transform infrared (FITR) spectroscopic imaging to study the effects of ageing, oestrogen level and altered dietary loading on the structure of MCC. MATERIALS AND METHODS: The Sprague-Dawley rats (n = 96) aged 5 and 14 months were divided into 12 subgroups according to age, oestrogen status (ovariectomized [OVX], non-ovariectomized [non-OVX)]) and diet (hard, normal, soft). Specimens of the MCC were examined with FTIR spectroscopic imaging to quantify the distribution of collagens and proteoglycans. MCC was divided sagittally into three segments: anterior, most superior and posterior. From each segment, the collagen and proteoglycan contents at different depths of cartilage were statistically compared between the groups using an N-way analysis of variance (ANOVA). RESULTS: The amount of collagen content was significantly associated with old age in the deep layer of the anterior segment and in the middle layer of the posterior segment of MCC. In the deep layer of the most superior segment, the collagen content also increased with ageing. The amount of proteoglycan content increased significantly when dietary loading increased, and the oestrogen level decreased in the deep layer of the most superior segment of MCC. CONCLUSION: Ageing, oestrogen level and altered dietary loading have a significant effect on the location and content of collagens and proteoglycans of rat MCC. Ageing significantly increased the amount of collagen content in the superior and posterior segments, being highest in the older soft-diet rats. Decreased oestrogen levels and increased dietary loading increased the amount of proteoglycan content.

Effectiveness of oral motor appliances on oral motor function and speech in children: a systematic review.

BACKGROUND: Different oral motor appliances have been used in connection with speech therapy to improve oral motor function and speech development, but no consensus has been reached on the effectiveness of the appliances. The objective was to systematically review the effectiveness of oral motor appliances on oral motor function and speech in children with speech sound disorders (SSDs) or oral motor dysfunctions. METHODS: A systematic search was conducted up to February 2023 in the PubMed, Scopus, and Cochrane databases. Inclusion criteria were prospective randomized or case-control clinical trials investigating the effect of intraoral appliances on orofacial function and/or speech. The risk of bias was evaluated by the Cochrane Collaboration's Robins-I tool. RESULTS: Nine publications of three individual studies met the inclusion and search criteria. Six of the publications were conducted in children with Down Syndrome (DS) and three publications were conducted in children with Cerebral Palsy (CP). No meta-analysis was made due to the limitations of the publications. Selected studies reported some beneficial effects of intraoral appliances on oral motor function in children with DS and CP, although the evidence is low. Due to the study design in selected studies and confounding factors, the overall risk of bias was categorized as moderate or high. DISCUSSION: Intraoral appliances may improve oral motor function in children with DS and CP. Due to lack of studies this review limited to children with DS and CP. The initial question concerning SSDs was not answered. Well-designed RCTs with larger sample sizes are needed, especially among non-syndromic children with SSDs. The level of evidence was considered very low.

Effects of headgear timing on dental arch changes from 7 to 18 years of age: a follow-up study.

BACKGROUND: Dental arch effects after cervical headgear (CHG) treatment have been researched from several different perspectives. However, the long-term effects of CHG timing are still unknown. OBJECTIVES: To analyse the long-term effects of CHG timing on dental arches. MATERIAL AND METHODS: A total of 67 children with Angle Class II malocclusion comprised the study group in this trial. The participants were randomized into two equal-sized groups. In the early group (EG, n = 33), treatment was started after the eruption of the first upper molars. In the later-timed group (LG, n = 34), treatment was started 18 months later compared with the early group. Long-term effects were measured from dental casts taken at five time points between 7 and 18 years of age. RESULTS: The total maxillary dental arch length was achieved earlier, the gained length persisted better in the long term, and significantly more space was achieved in EG compared with LG (P = .048). The intermolar width in the maxillary dental arch was more stable and was reached earlier in EG compared with LG (P = .002). The results showed that in terms of total mandibular arch length increases, EG males benefited the most and LG females the least from CHG treatment (P = .031). CONCLUSIONS: Both genders benefited from earlier CHG treatment. The maxillary dental arches remained longer, and the final width was gained earlier in EG compared with LG.

The relation of temporomandibular disorders with oral health-related quality of life in the Northern Finland Birth Cohort 1966.

OBJECTIVE: This study aimed to evaluate the association between temporomandibular disorders (TMD) and oral health-related quality of life (OHRQoL) in an adult population. METHODS: The data included 1,768 adults 46 years of age in the Northern Finland Birth Cohort 1966 (NFBC1966) study. The symptoms, signs and diagnoses of TMD were assessed using a modified protocol of the Diagnostic Criteria for TMD (DC/TMD) and validated questionnaires. OHRQoL was measured using the Oral Health Impact Profile (OHIP-14). Associations of TMD and OHRQoL were evaluated with χ2 -test and Fisher's exact test. RESULTS: In females, pain-related TMD signs and diagnoses associated significantly with prevalence of OHIP total and all dimensions, whereas in joint-related TMD, psychological dimensions showed the strongest association. Males with pain- or joint-related TMD, the most impaired dimension was physical pain. CONCLUSION: Pain-related TMD seems to associate more strongly with lower OHRQoL than joint-related TMD especially in females.

The association between dental and facial symmetry in adolescents.

INTRODUCTION: Facial aesthetics have become one of the most important objectives of orthodontic treatment. The correction of dental arches should be performed in accordance with the face. This study explored the association between occlusal and facial asymmetries in adolescents, particularly emphasizing a Class II subdivision. METHODS: Eighty-one adolescents (43 males, 38 females) with a median age of 15.9 (interquartile range, 15.17-16.33) years were enrolled. Of these patients, 30 had a Class II subdivision (right side, n = 12; left side, n = 18). Three-dimensional facial scans were analyzed using surface- and landmark-based methods. Chin asymmetry was determined using the chin volume asymmetry score. Three-dimensional intraoral scans were analyzed to assess occlusal asymmetry. RESULTS: The surface matching scores were 59.0% ± 11.3% for the whole face and 39.0% ± 19.2% for the chin. Chin volume was larger on the right side than on the left side in most patients (n = 51, 63%), and it was associated with a dental midline shift to the corresponding subdivision side. A correlation between dental and facial asymmetries was noted. In addition, the dental midline shifted to the left in patients with a Class II subdivision, regardless of the side, and to the right in those with a symmetrical Class II subdivision. However, several patients did not possess asymmetrical occlusal traits sufficient for statistical analysis. CONCLUSIONS: Dental asymmetry was weak but significantly correlated with facial asymmetry.

A longitudinal study of facial asymmetry in a normal birth cohort up to 6 years of age and the predisposing factors.

OBJECTIVES: This prospective, population-based cohort study aimed to investigate the development of facial asymmetry up to 6 years of age using a three-dimensional (3D) soft tissue imaging method in a normal population. In addition, the study sought to identify potential predisposing factors to facial asymmetry. METHODS: A total of 102 newborns were enrolled in the study at birth. 3D stereophotogrammetric images of the head and face were analysed at the ages of 12 months (T1), 3 years (T2), and 6 years (T3). The surface-based analysis involved the calculation of the average distance (mm) and the symmetry percentage (%) between the original and mirrored surfaces. For landmark-based analysis, the distance of facial landmarks to the facial midline was examined. RESULTS: The final analysis included 70 (68.6%) subjects. Surface-based analysis showed a significant improvement of facial symmetry from T1 to T3 in all facial areas. Landmark-based analysis showed that upper facial landmarks were located, on average, slightly on the left and lower facial landmarks slightly on the right in relation to the facial midline (P < 0.001). LIMITATIONS: The size of the study population was limited. Facial posture may affect the reliability of the results, especially in younger children. CONCLUSION: Facial asymmetry is detectable in early childhood and tends to reduce with age in young children. The lower face deviates slightly to the right, and the upper face to the left in relation to the facial midline. Possible predisposing factors for facial asymmetry at the age of 6 years include deformational plagiocephaly, sleeping position, and previous facial asymmetry.

Occlusal characteristics and oral health-related quality of life in adults operated due to sagittal synostosis in childhood: a case-control study with 26 years of follow-up.

PURPOSE: The aim of this case-control study was to investigate occlusal characteristics, received orthodontic treatment, oral health-related quality of life (OHRQoL), and satisfaction with dental esthetics in adults operated due to sagittal synostosis. METHODS: The study group consisted of 40 adults (25 males, 15 females, mean age 27.4 years, range 18-41) who were operated due to isolated sagittal synostosis in childhood. The control group comprised 40 age and gender-matched adults. Occlusal characteristics were evaluated clinically during study visits. Information on the previous orthodontic treatment was collected from dental records. OHRQoL was measured using the 14-item Oral Health Impact Profile (OHIP-14), and satisfaction with dental esthetics was evaluated using a visual analogue scale. RESULTS: No statistically significant differences were found between the patient group and the controls in malocclusion traits (overjet, overbite, molar relationships, crossbite, scissor bite), previous orthodontic treatment, pre-treatment malocclusion diagnoses, OHIP variables, or satisfaction with dental esthetics. However, there was a tendency toward increased overjet and overbite in scaphocephalic patients. CONCLUSION: It seems that adults with scaphocephaly operated in childhood do not differ from the average population in terms of occlusion, received orthodontic treatment, or oral health-related well-being.

The associations of dental aesthetics, oral health-related quality of life and satisfaction with aesthetics in an adult population.

AIM: The aim of this study was to investigate the gender-specific associations between dental aesthetics, oral health-related quality of life (OHRQoL), and satisfaction with dental aesthetics in an adult population. MATERIALS AND METHODS: The study population consisted of 1780 individuals (822 males and 958 females) from the Northern Finland Birth Cohort 1966 (NFBC1966). Dental aesthetics were evaluated from digital 3D dental models using the Aesthetic Component (AC) of the Index of Orthodontic Treatment Need (IOTN). Layperson and orthodontist panels evaluated the dental aesthetics of a smaller sample (n = 100). OHRQoL was measured using the Oral Health Impact Profile (OHIP-14) questionnaire. Satisfaction with dental aesthetics was asked with one separate question. Gender-specific analyses consisted of Mann-Whitney U-tests and Spearman's correlation coefficients. RESULTS: More than half of the population had an aesthetically acceptable occlusion, and most of the individuals were satisfied with the aesthetics. The most severe aesthetic impairments were associated with the psychological dimensions of OHIP-14. There were significant but weak associations of AC and satisfaction with aesthetics, and satisfaction with aesthetics and OHRQoL. Significant gender differences were found, men having higher mean AC scores but women reporting lower OHRQoL. CONCLUSION: At the population level, most of the individuals were satisfied with their aesthetics, despite different dental aesthetic conditions. The most severe aesthetic impairments were associated with decreased psychological well-being, women reporting more impacts compared to men.

Association of climacterium with temporomandibular disorders at the age of 46 years - a cross-sectional study.

OBJECTIVE: Hormonal factors have been suggested to contribute to female dominance among subjects with temporomandibular disorders (TMD). Aim of the study was to examine the association of climacteric status with TMD amongst female participants in the Northern Finland Birth Cohort (NFBC) 1966 at 46 years of age. MATERIAL AND METHODS: Among female subjects in NFBC1966, climacteric status was determined based on menstrual anamnesis and measurement of blood follicle-stimulating hormone (FSH) levels. Women with FSH > 25 IU/L and amenorrhoea > 4 months were defined as climacteric (case group, n = 71); women not diagnosed as climacteric were defined as preclimacteric (control group, n = 656). Differences between cases and controls were evaluated on self-reported TMD pain, clinical TMD signs and TMD diagnoses using modified Diagnostic Criteria for TMD (DC/TMD) protocol. Crosstabulation and logistic regression models were used to analyse differences between cases and controls. RESULTS: Compared to preclimacteric women, climacteric women had significantly more often pain on palpation in temporomandibular joints (TMJs) (OR = 2.64, 95% CI 1.12-6.21, p= .026) and more crepitus in TMJs (OR = 2.92, 95% CI 1.13-7.56, p= .027). Degenerative joint disease diagnoses were more common in climacteric than preclimacteric women (OR = 2.27, 95% CI 1.05-4.91, p= .037). Differences were statistically significant after adjusting for confounding factors (body mass index (BMI), smoking, parity). No statistically significant differences in self-reported TMD pain were noted between groups. CONCLUSION: Among females at the age of 46 years, climacterium seems associated with TMD by increasing pain on palpation in TMJs, subjective symptoms, and clinical signs indicating degenerative changes in TMJs when using DC/TMD.

Prevalence of sagittal molar and canine relationships, asymmetries and midline shift in relation to temporomandibular disorders (TMD) in a Finnish adult population.

OBJECTIVE: To examine the prevalence of sagittal relationships, asymmetries and midline shift, and their associations with temporomandibular disorders (TMD) in the Northern Finland Birth Cohort 1966 (NFBC1966). MATERIALS AND METHODS: 1845 subjects participated in a clinical examination at the age of 46. Occlusal measurements were performed using 3D models. Symptoms of TMD were screened using validated questions, and signs and diagnoses of TMD were assessed using a modified protocol of the Diagnostic Criteria for TMD (DC/TMD) and questionnaires. Associations between variables of occlusion and TMD were evaluated with χ2-test and Fisher's exact test and using logistic regression analyses, adjusted for self-reported general health, mental health, bruxism, and rheumatoid arthritis. RESULTS: The most common sagittal relationships were Class I and normal canine relationship. Half-cusp Class II and post-normal canine relationship were more frequent in females, and Class III and pre-normal canine relationship in males. Deviations from normal cuspid or molar relationships showed a weak but statistically significant association with TMD, especially in females. Half-cusp Class II and Class II relationships were more frequent in relation to joint-related TMD signs and diagnoses while missing canines were associated with pain-related TMD diagnoses. CONCLUSIONS: The present study findings gave some indications that canine relationships are associated with pain-related TMD, whereas Angle II sagittal occlusal relations may associate with joint-related TMD. Occlusal characteristics should therefore be taken into account as one possible associating factor in subjects with TMD.

Occlusal characteristics in facial pain cases and controls - 12-year follow-up of the Northern Finland Birth Cohort (NFBC) 1966.

Objective: The purpose of this study was to investigate the occlusal characteristics in Finnish adults at 12-year follow-up based on the Northern Finland Birth Cohort 1966 (NFBC1966) subjects.Methods: The occlusal analyses were performed at ages 34 and 46 years of facial pain cases (n = 52) and controls (n = 49) by two different methods.Results: At 12-year follow-up, a significant decrease in upper anterior segment peer assessment rating (PAR) score was found in the controls, indicating improvement in teeth alignment. In facial pain cases, left lateral occlusal relationship and midline asymmetry were significantly decreased. Occlusal asymmetry and overjet were significantly increased. In controls, the left canine showed a more normal occlusal relationship, cuspid asymmetry was changed, and midline asymmetry was significantly decreased.Conclusion: During a 2-year period, occlusal asymmetry and overjet increased significantly in facial pain cases, while occlusal relationship showed more normal characteristics in controls.

Effects of force magnitude on dental arches in cervical headgear therapy.

AIM: To study the influence of different force magnitudes on dental arches in cervical headgear (CHG) treatment. MATERIAL AND METHODS: In this controlled clinical trial, patients (n = 40) were treated with CHG with light (L, 300 g, n = 22) or heavy force (H, 500 g, n = 18) magnitude. Subjects were asked to use CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was raised 10-20 degrees and the inner bow expanded 3-4 mm. Adherence to instructions and force magnitude were monitored with an electronic module (Smartgear, Swissorthodontics, Switzerland). Impressions for study models were taken before (T1) and after (T2) treatment and the study models were scanned into digital form (3Shape, R700 Scanner, Denmark). Measurements were made using the digital models (Planmeca Romexis, Model analyser, Finland). RESULTS: During the treatment (T1-T2) the upper inter-canine distance increased by 2.83 mm (P = 0.000) and 2.60 mm (P = 0.000) in the L and H force magnitude groups, respectively. Upper inter-molar width increased by 3.16 mm (P = 0.000) and 2.50 mm (P = 0.000) in the L and H groups, respectively. Maxillary total arch perimeter increased by 6.39 mm (P = 0.001) and 6.68 mm (P = 0.001) in the L and H groups, respectively. In the amount of change over time, T1-T2, in the upper arch measurements, no significant difference was found between the groups. Lower inter-canine width increased by 0.94 mm (P = 0.005) and 1.16 mm (P = 0.000) in the L and H groups, respectively; no difference between the groups. Lower inter-molar distance increased by 2.17 mm (P = 0.000) and 1.11 mm (P = 0.008) in the L and H groups, respectively. At the end of the study, upper and lower inter-molar width was larger in the L group than in the H group (P = 0.039 and P = 0.022, respectively). CONCLUSION: CHG therapy is an effective method for expanding and releasing moderate crowding of the upper dental arch. The lower arch spontaneously follows the upper arch in widening effects, and minor expansion can also be seen on the lower arch. In the L group, larger inter-molar width was achieved on the upper and lower arch; probably due to better adherence to instructions. Light force is recommended for use in CHG therapy.

Association of temporomandibular disorders with pain sensitivity: A cohort study.

BACKGROUND: Pain related to temporomandibular disorders (TMD) can be linked with multiple site pain (MSP), and may associate with increased pain sensitivity, more frequently among women than men. The aim of the study was to examine the associations of pressure pain threshold (PPT) and tolerance (PPTo) with TMD and associated MSP in the Northern Finland Birth Cohort 1966 (NFBC1966) study. METHODS: Altogether 1961 NFBC1966 subjects attended clinical medical and dental examination at the Institute of Dentistry, University of Oulu in 2012-2013. Clinical examinations were carried out using a modified Diagnostic Criteria for TMD protocol (DC/TMD). MSP was defined based on questions regarding body pain sites. Additionally, PPT and PPTo were assessed using algometer measurements. Mann-Whitney U-test and Tobit regression models were used to analyse associations between TMD sub-diagnoses, MSP, PPT and PPTo, stratified by sex. Further models were adjusted with anxiety and depressive symptoms, which were assessed using Hopkins Symptom Checklist-25 (HSCL-25) and two-way interaction terms. RESULTS: Among females, lower PPT and PPTo were associated with myalgia and arthralgia. Among males, lower PPT and PPTo were associated with MSP-linked TMD. Tobit regression analysis showed significantly lower PPT and PPTo values in the myalgia and arthralgia subgroups among female TMD subjects. Among females, disc displacement with reduction had an inverse association with PPT and PPTo. Among males, lower PPTo was associated with degenerative joint disease and MSP-linked TMD. CONCLUSIONS: The pain regulatory mechanisms behind TMD act differently between the genders as local TMD among females and MSP-linked TMD among males were associated with pain sensitivity. SIGNIFICANCE: The study shows that there are differences in the associations of painful TMD with pressure pain tolerance, pressure pain sensitivity and MSP between male and female subjects.

Profile shape variation and sexual dimorphism amongst middle-aged Northern Europeans.

AIM: To explore profile shape variation in a large population of middle-aged individuals and investigate features of sexual dimorphism. MATERIALS AND METHODS: Facial profile photographs of 1776 individuals (964 females and 812 males; 46 years old), members of the Northern Finland Birth Cohort 1966 (NFBC1966), were uploaded and digitized with Viewbox software. Profile shape was defined with 47 landmarks (4 fixed and 43 sliding semi-landmarks). Digitized images were reoriented and scaled with Procrustes Superimposition, and shape variation was determined with a Principal Component Analysis. RESULTS: More than 90 per cent of profile shape variation was explained by Principal Components (PC) 1-9. PC1, explaining the largest amount of variation (33.1 per cent) described changes in facial convexity, slope of the forehead, lip, and chin protuberance. PC2 (23.1 per cent variation) was more related to vertical changes of the lower facial third and PC3 (11 per cent variation) primarily described changes in lip protrusion and nasal projection. Shape analysis showed a significant difference between the average female and the average male profile shape (P < 0.001); however, this was not evident upon visual observation. The shape variable most associated with sex was PC3 (η 2 = 0.245; P < 0.001), which described changes in lip prominence and in projection of the dorsal nasal surface. An additional discriminant analysis showed that profile shape predicted sex in 76 per cent of males and 79.6 per cent of females. CONCLUSIONS: There is significant sexual dimorphism in facial profile among middle-aged adults. Profile shape variation was associated to changes in lip protrusion, nasal protuberance, and chin projection.

Associations of sagittal malocclusions with dental arch characteristics and crowding in Northern Finland Birth Cohort 1966.

OBJECTIVE: To analyse the associations between the widths and forms of dental arches, malocclusions and crowding in middle-aged adult population. MATERIALS AND METHODS: The study material is part of the Northern Finland Birth Cohort 1966 (NFBC1966); the subjects were examined at the age of 46 years. A total of 781 adults with full dentition and no orthodontic treatment history were included. Overjet, overbite, cross-bite and scissor bite were examined during clinical examination. The widths and forms of dental arches, molar relationships and crowding were measured using three-dimensional (3D) dental models. RESULTS: Dental arches were significantly larger in males than in females. Class II (CII) occlusion and increased overjet (≥6 mm) were associated with narrow maxilla (P < .001, P < .05 respectively). Subjects with lateral cross-bite had significantly narrower maxilla and wider mandible (P < .05) than subjects with normal lateral occlusion. In subjects with CII occlusion, square or tapered maxilla and tapered or ovoid mandible were significantly more frequent compared to subjects with Class I (CI) occlusion (P < .05). CII occlusion was significantly associated with crowding in the maxilla (P < .01). CONCLUSION: Narrow and tapered-shaped maxilla was related to CII occlusion, which was associated with dental crowding in the maxilla. Malocclusions were more likely to be found together with other malocclusions than alone.

Malocclusion severity and its associations with oral health-related quality of life in an adult population.

AIM: The aim of this study was to investigate malocclusion severity and its associations with oral health-related quality of life (OHRQoL) among middle-aged adults. MATERIALS AND METHODS: The study material consisted of 1786 subjects from the Northern Finland Birth Cohort 1966 who attended dental and oral examination as part of the 46-year-old follow-up study. Malocclusion severity was assessed using the Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN) and the Peer Assessment Rating index (PAR) from digital 3D dental models. Participants also answered a questionnaire including the Oral Health Impact Profile (OHIP-14) and a question on their satisfaction with occlusal function. Differences between malocclusion severity groups were evaluated for both genders separately. For adjusted models, multivariate Poisson regression models were conducted. RESULTS: In this study population, 31.3% had great or very great orthodontic treatment need according to DHC and the mean PAR total score was 22.05. The most severe malocclusions were associated with OHRQoL, especially the psychosocial and handicap dimensions, and satisfaction with occlusal function. There was a significant difference between genders, men having more severe malocclusion but women reporting more OHRQoL impacts. CONCLUSION: One third of the study population were considered to have severe malocclusion. There was an association between malocclusion severity and OHRQoL in adult population, particularly in women.

Associations between Bolton ratio and overjet deviations in a Finnish adult population.

OBJECTIVE: To determine the anterior Bolton ratio for a Finnish adult population and to investigate its associations with overjet. MATERIAL AND METHODS: This study is part of the Northern Finland Birth Cohort 1966. Clinical oral investigations, including three-dimensional intraoral scanning and registration of occlusion, were performed in connection with the 46-year follow-up for 1,961 subjects. Subjects with normal occlusion (n = 149), extreme overjet ≥ 8 mm (n = 49), large overjet 6-7 mm (n = 86), and negative overjet (n = 16) and no orthodontic treatment history were selected for further analysis. The mesiodistal widths were measured from canine to canine to evaluate the anterior Bolton ratio. RESULTS: A mean anterior Bolton ratio of 78.6 (SD 3.1) was found for the normal occlusion group. Subjects with extreme overjet had smaller Bolton ratios compared to the normal occlusion group and the negative overjet group (p = .005, p = .019, respectively). Overjet deviations were associated with upper canine and incisor widths. CONCLUSIONS: The mean anterior Bolton ratio in subjects with normal occlusion was larger compared to the original Bolton ratio. Tooth size discrepancy was associated with extreme and negative overjet at population level.

The impact of force magnitude on the first and second maxillary molars in cervical headgear therapy.

AIM: To study the effect of force magnitude on the maxillary first and second molars in cervical headgear (CHG) therapy. MATERIAL AND METHODS: In this controlled clinical trial, patients (n = 40) were treated with CHG with a light (L, 300 g, n = 22) or a heavy force (H, 500 g, n = 18) magnitude. The subjects were asked to wear CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was lifted up for 10-20 degrees and the inner bow was expanded 3-4 mm. Adherence to instructions and force magnitude were monitored using an electronic module (Smartgear, Swissorthodontics, Switzerland). Panoramic and lateral radiographs before (T1) and after treatment (T2) were analysed using a Romexis Cephalometric module (Planmeca, Finland) focussing on the angular, sagittal, and vertical positions of the permanent first and second molars. RESULTS: According to the cephalometric analysis of the maxillary first and second molars, distal tipping occurred during T1-T2 in the H group (P = 0.010 and 0.000, respectively), and the change was greater in the H group compared to the L group (P = 0.045 and 0.019, respectively). Based on the panoramic analysis, tipping occurred in the distal direction during therapy in the H group in the second molars compared to the midline or condylar line (P = 0.001 and 0.001; P = 0.008 and 0.003 on the right and left, respectively). CONCLUSION: With heavy force magnitude, the maxillary first and second molars can tilt more easily in the distal direction even if the CHG was used less. Distal tipping of the molar can be considered to be a side effect of CHG therapy.

Incisor Occlusion Affects Profile Shape Variation in Middle-Aged Adults.

BACKGROUND: The aim of this study was to assess the effect of overjet and overbite on profile shape in middle-aged individuals. METHODS: The study population comprised 1754 46-year-old individuals, members of the 1966 Northern Finland Birth Cohort. Their profile images were digitized using 48 landmarks and semi-landmarks. The subsequent landmark coordinates were then transformed to shape coordinates through Procrustes Superimposition, and final data were reduced into Principal Components (PCs) of shape. Overjet and overbite values were measured manually, during a clinical examination. A multivariate regression model was developed to evaluate the effect of overjet and overbite on profile shape. RESULTS: The first nine PCs described more than 90% of profile shape variation in the sample and were used as the shape variables in all subsequent analyses. Overjet predicted 21.3% of profile shape in the entire sample (η2overjet = 0.213; p < 0.001), while the effect of overbite was weaker (η2overbite = 0.138; p < 0.001). In males, the equivalent effects were 22.6% for overjet and 14% for overbite, and in females, 25.5% and 13.5%, respectively. CONCLUSION: Incisor occlusion has a noteworthy effect on profile shape in middle-aged adults. Its impact becomes more significant taking into consideration the large variety of genetic and environmental factors affecting soft tissue profile.

Effect of cervical headgear on dental arch area, shape and interarch dimensions : A randomized study.

PURPOSE: The goal was to study the effects of early cervical headgear treatment on maxillary and mandibular dental arch area, shape and interarch dimensions. METHODS: The total study group comprised 67 children aged 7.6 years (standard deviation 0.3) with Angle class II malocclusion collected between 1992 and 1996. The children were randomly divided into two groups of equal size. In the first group, cervical headgear treatment was started immediately and undertaken for 2 years. The remaining patients served as untreated controls. Dental casts were taken and scanned at the beginning of treatment (T0) and at the 2­year (T1) and 4­year follow-up (T2). Three-dimensional landmarks describing the positions of maxillary and mandibular incisors, canines, first and second premolars and first molars were used to calculate and visualize the maxillary and mandibular dental arch area and shape using the polynomial equation y = Ax6 + Bx2. RESULTS: Significant changes in the shape and area of both maxillary and mandibular dental arches were induced with cervical headgear. The headgear increased dental arch area, sagittal dimensions at the mid-sagittal line and transversal dimensions at all of the measured levels in both dental arches compared to the control group. CONCLUSIONS: Cervical headgear is an effective treatment device to gain space in both dental arches. Furthermore, when used as an early phase treatment, relapse is relatively small compared to the gained space.