Pertti Pirttiniemi

Dental arch morphology in children with sleep-disordered breathing

The aim of the present study was to examine the effects of nocturnal breathing disorders such as obstructive sleep apnoea (OSA) and snoring on developing dental arches. The study group comprised 41 children (22 males, 19 females, mean age 7.2 years, standard deviation 1.93) with diagnosed OSA. Age- and gender-matched groups of 41 snoring and 41 non-obstructed control children were selected. Orthodontic examination was carried out and dental impressions were taken. Malocclusions were diagnosed clinically and 13 linear variables were measured from the dental casts. The differences between the dental arch measurements of the OSA, snoring, and control groups were studied using analysis of variance followed by Duncans multiple comparison method. Children with diagnosed OSA had a significantly increased overjet, a reduced overbite, and narrower upper and shorter lower dental arches when compared with the controls. Snoring children had similar but not as significant differences as OSA children when compared with the controls. There were more children with an anterior open bite (AOB) in the OSA group (P=0.016) and with a Class II or asymmetric molar relationship in the groups of OSA (P=0.013) and snoring (P=0.004) subjects compared with the non-obstructed controls. There were more subjects with mandibular crowding (P=0.002) and with an AOB (P=0.019) with an increasing obstructive apnoea-hypopnoea index (AHI). These findings are in agreement with previous studies of the effects of increased upper airway resistance on dental arch morphology and can be explained by long-term changes in the position of the head, mandible, and tongue in order to maintain airway adequacy during sleep.

Effect of Mechanical Forces on Chondrocyte Maturation and Differentiation in the Mandibular Condyle of the Rat

The effects of mechanical factors on the growth of the mandibular condyle were studied by monitoring the maturation of the mesenchymal cells in 55 rats. Thirty-five animals were fed normal pellet food, and 20 were fed a soft diet and their incisors were cut regularly. 3H-thymidine was injected intraperitoneally three days before death at 18, 23, or 33 days. Histologic sections showed the most advanced 3H-thymidine-labeled cells to occur deep in the cartilage, in the lower hypertrophic cell layer in anterior and posterior regions of the condyle, and in the upper hypertrophic cell layer in the superior region at the age of 18 days. A distinct difference in the maturation state of the labeled cells could also be observed between these regions. In animals fed a soft diet, maturation was slower in the superior region of the condyle and faster in the posterior region than in the normal rats. The rate at which cells stepped out of the proliferating cell pool was measured by use of monoclonal antibodies against proliferating cell nuclear antigen. The ratio between labeled cells in the proliferating cell layer and the number of labeled cells beneath it was greater in control animals than in the soft-diet animals. The rate of differentiation and maturation of mesenchymal cells into chondrocytes seems to be controlled by mechanical factors.

Abnormal mandibular growth and the condylar cartilage

Deviations in the growth of the mandibular condyle can affect both the functional occlusion and the aesthetic appearance of the face. The reasons for these growth deviations are numerous and often entail complex sequences of malfunction at the cellular level. The aim of this review is to summarize recent progress in the understanding of pathological alterations occurring during childhood and adolescence that affect the temporomandibular joint (TMJ) and, hence, result in disorders of mandibular growth. Pathological conditions taken into account are subdivided into (1) congenital malformations with associated growth disorders, (2) primary growth disorders, and (3) acquired diseases or trauma with associated growth disorders. Among the congenital malformations, hemifacial microsomia (HFM) appears to be the principal syndrome entailing severe growth disturbances, whereas growth abnormalities occurring in conjunction with other craniofacial dysplasias seem far less prominent than could be anticipated based on their often disfiguring nature. Hemimandibular hyperplasia and elongation undoubtedly constitute the most obscure conditions that are associated with prominent, often unilateral, abnormalities of condylar, and mandibular growth. Finally, disturbances of mandibular growth as a result of juvenile idiopathic arthritis (JIA) and condylar fractures seem to be direct consequences of inflammatory and/or mechanical damage to the condylar cartilage.

Cephalometric evaluation of children with nocturnal sleep-disordered breathing

The present study aimed to assess the cephalometric features in children with sleep-disordered breathing (SDB). The subjects were 70 children (34 boys and 36 girls, mean age 7.3, SD 1.72, range 4.2-11.9 years) with habitual snoring and symptoms of obstructive sleep disorder for more than 6 months. On the basis of overnight polygraphic findings, the subjects were further divided into subgroups of 26 children with diagnosed obstructive sleep apnoea (OSA), 17 with signs of upper airway resistance syndrome (UARS), and 27 with snoring. A control group of 70 non-obstructed children matched for age and gender was selected. Lateral skull radiographs were taken and cephalograms were traced and measured. The differences between the matched groups were studied using t-test for paired samples. Differences between the subgroups were studied using analysis of variance followed by Duncans multiple comparison method. Children with SDB were characterized by an increased antero-posterior jaw relationship (P = 0.001), increased mandibular inclination in relation to the palatal line (P = 0.01), increased total (P = 0.019) and lower (P = 0.005) anterior face heights, a longer (P = 0.018) and thicker (P = 0.002) soft palate, smaller airway diameters at multiple levels of the naso- and oropharynx, larger oropharyngeal airway diameter at the level of the base of the tongue (P = 0.011), lower hyoid bone position (P = 0.000), and larger craniocervical angles (NSL-CVT, P = 0.014; NSL-OPT, P = 0.023) when compared with the non-obstructed controls. When divided into subgroups according to the severity of the disorder, OSA children deviated significantly from the control children especially in the oropharyngeal variables. Children with UARS and snoring also deviated from the controls, but the obstructed subgroups were not confidently distinguishable from each other by cephalometric measurements. Logistic regression analysis indicated that UARS and OSA were associated with decreased pharyngeal diameters at the levels of the adenoids (PNS-ad1) and tip of the uvula (u1-u2), an increased diameter at the level of the base of the tongue (rl1-rl2), a thicker soft palate, and anteriorly positioned maxilla in relation to the cranial base. Lateral cephalogram may thus reveal important predictors for SDB in children. Attention should be paid to pharyngeal measurements. Systematic orthodontic evaluation of SDB children is needed because of the effects of obstructed sleep on the developing craniofacial skeleton.

Comparison of amounts and properties of collagen and proteoglycans in condylar, costal and nasal cartilages.

In this study we compared the compositions of extracellular matrices of condylar, costal and nasal cartilages to characterize differences in growth patterns in relation to matrix composition. Condylar, costal and nasal cartilages of 25- and 35-day-old rabbits were extracted and subjected to bio- and histochemical analysis to determine total amounts of collagen and amounts and aggregating properties of proteoglycans. We found that proteoglycan content and aggregate formation were greatest in nasal cartilage, and lower in costal and markedly lower in condylar cartilage. The amount of proteoglycans increased by varying amounts in all samples with age. Collagen content was highest in costal cartilage. In 25-day-old rabbits the quantity of collagen in condylar cartilage exceeded that in nasal cartilage. In 35-day-old rabbits the quantities were nearly the same. It is suggested that collagen does not only provide tensile strength, but counteracts forces responsible for interstitial growth such as osmotic pressure. Based on the results, it seems that the amount of proteoglycans is greater in cartilages, which have greater independent growth potential. Variations in increase in amount of proteoglycans with age could reflect differences in the timing of growth of such cartilages.

Normal and increased functional asymmetries in the craniofacial area

Normal asymmetry in the area of the craniofacial skeleton can be directional or fluctuating in nature. Directionality can in principle be found in three dimensions: anteroposterior, cranio-caudal, and asymmetries in the left-right dimension. When it comes to directional left right differences, an explanation has been difficult to find, although expressions of this type are obvious. Recent findings made in molecular genetics strongly support the genetic inheritance pattern of laterality. When functionally increased asymmetries of facial structures are concerned, it is often difficult to determine the exact contribution of each factor involved. In the light of recent experimental data, however, it seems that the influence of occlusion on the development of balanced facial structures is highly important during the early periods of life. A review of these factors is given in this article.

Validity of upper airway assessment in children A clinical, cephalometric, and MRI study

OBJECTIVE To test the hypothesis that the capability of two-dimensional lateral cephalogram in recognizing pharyngeal obstruction is poor compared with the capability of three-dimensional magnetic resonance imaging (MRI) and clinical observation of tonsillar size. MATERIALS AND METHODS The study participants were 36 prepubertal children (19 male, 17 female; mean age 7.3 ± 1.43 years, range 4.8-9.8 years) with sleep-disordered breathing diagnosed by nocturnal polygraphy. Pharyngeal airway was imaged with a low-field open-configuration MRI scanner. Tonsillar size was clinically determined and lateral skull radiographs were taken and measured. Pearson correlation coefficients were calculated between the clinical, cephalometric, and MRI variables. RESULTS Nasopharyngeal and retropalatal cephalometric variables had a significant positive correlation with the MRI findings. Both techniques showed the narrowest measurement to be located in the retropalatal region. Clinical assessment of tonsillar size correlated inversely with MRI findings such as minimal retropalatal cross-sectional airway area (P  =  .000), minimal retroglossal cross-sectional airway area (P  =  .015), and intertonsillar airway width (P  =  .000). Cephalometric soft palate and tonsillar area correlated with clinical tonsillar size (P  =  .001). CONCLUSIONS The hypothesis is rejected. The findings confirm that the lateral cephalogram is a valid method for measuring dimensions of the nasopharyngeal and retropalatal region. When evaluating oropharyngeal size, clinical assessment of tonsillar size is a relatively reliable method.

Dental esthetics and quality of life in adults with severe malocclusion before and after treatment

OBJECTIVE To investigate the association between satisfaction with dental esthetics and quality of life, and esthetics satisfaction in relation to esthetic evaluations of three panel groups. MATERIALS AND METHODS Fifty-two patients (36 women, 16 men; age 18-61 years) with severe malocclusion were treated in Oulu University Hospital. Of these, 38 and 14 patients underwent orthodontic/surgical treatment and orthodontic treatment, respectively. A questionnaire and dental photographs were collected before and after treatment. The 14-item Oral Health Impact Profile (OHIP-14) was used to measure oral health-related quality of life. Satisfaction with dental esthetics was evaluated using the Visual Analogue Scale. Dental photographs were presented to three panel groups: 30 laypersons, 30 dental students, and 10 orthodontists, who rated the photographs using the Aesthetic Component of the Index of Orthodontic Treatment Need. RESULTS Oral health-related quality of life (OHIP-14 severity score) and esthetic satisfaction (according to the Visual Analogue Scale) improved after the treatment (P < .001). The most unsatisfied patients reported oral effects more often both before and after treatment. Changes in oral health-related quality of life components of severity, psychological discomfort, and psychological disability correlated positively with the changes in esthetic satisfaction. Orthodontists graded the situation before treatment as worse and the outcome as better than the laypersons; the level of grading by dental students fell between these two groups. CONCLUSION Improvement in esthetic satisfaction due to the treatment of severe malocclusion improves oral health-related quality of life, particularly by decreasing psychological discomfort and psychological disability.

Three-dimensional longitudinal assessment of facial symmetry in adolescents.

Recent advances in laser scanning technology provide the opportunity to examine faces in three dimensions. The aim of this prospective clinical study was to explore facial symmetry in healthy growing individuals and determine whether asymmetric changes occur during adolescent growth. Non-invasive laser surface scanning was performed to capture facial images of 60 Caucasian Finnish adolescents (30 males and 30 females, mean 11.5 years). Facial symmetry was analysed on images obtained at the initial scanning (T₁), 2.5 (T₂), and 4.5 (T₃) years thereafter. The final sample consisted of 39 adolescents (19 males and 20 females, mean 16 years). Three-dimensional images were processed and analysed using an in-house developed subroutine for commercial software. A mirror image was generated and superimposed on the original image to create a symmetric face and establish the midsagittal plane. The surface matching of the original face and the mirror face (amount of symmetry) was measured for the whole face, upper, middle, and lower thirds at tolerance level 0.5 mm and presented with colour maps. Three angular and 14 linear measurements were made based on 21 soft tissue landmarks, which have proven to be reliable. The results of the Friedman test showed that facial symmetry parameters did not significantly differ over time (P > 0.05). Mann-Whitney U-test did not reveal statistically significant differences between genders at any time point (P > 0.05). Facial growth of healthy individuals during adolescence is symmetric, although further investigation on larger randomized sample is suggested.

Head posture and dentofacial asymmetries in surgically treated muscular torticollis patients.

Muscular torticollis is a medically well-known condition that is usually diagnosed in early childhood and in which early surgical intervention is recommended to prevent the development of facial asymmetries. The purpose of this study is to examine head posture and possible dentofacial asymmetries in patients who have undergone surgical treatment for muscular torticollis in early childhood. Natural head position roentgenograms were taken in frontal projection, a clinical examination of oral status was performed, and dental casts were made. Marked craniofacial and dental asymmetries were observed, combined with a deviant head posture, in spite of surgical treatment for muscular torticollis earlier in childhood.