Stavros Kiliaridis

The relationship between maximal bite force, bite force endurance, and facial morphology during growth: A cross-sectional study

The aims of this investigation were to study the relation between facial morphology and bite force at different ages during growth and to investigate possible relations between bite force and the variables age, finger force, stature, and sex in growing healthy individuals. One hundred and thirty-six individuals were included, consisting of six groups of males and females, 7-9, 10-12, and 20-24 years old. Standardized photographs were taken to determine the facial type. The occlusal relationship, body height, finger force, maximal bite force, and bite force endurance amplitude were recorded. All bite force variables and finger force increased with age in both sexes. A positive correlation was found between the maximal bite force in the incisor region and the ratio of upper to lower facial height; this is, subjects with a high bite force had a relatively short lower anterior height. The maximal bite force for molars and endurance amplitude were positively correlated to stature and finger force but not to facial characteristics. A longitudinal study to follow each individual child during growth would be of interest to evaluate the importance of muscular influence on facial growth.

Detection of apical root resorption after orthodontic treatment by using panoramic radiography and cone-beam computed tomography of super-high resolution

INTRODUCTION Apical root resorption is an adverse side effect of orthodontic treatment. We compared panoramic radiography (OPT) with cone-beam computed tomography (CBCT) in evaluating orthodontically induced apical root resorption. METHODS The study sample comprised 275 teeth in 22 patients near the end of orthodontic treatment with fixed appliances. Two calibrated examiners assessed blindly the presence or absence and the severity of apical root resorption on the OPT images after treatment and the corresponding reconstructed CBCT images. Resorption was evaluated as no, mild, moderate, severe, and extreme. RESULTS On the OPT images, 17 teeth (6.2%) could not be evaluated. Statistically significant differences were found between the 2 methods: 56.5% and 31% of the teeth showed no resorption by OPT and CBCT, respectively; 33.5% and 49% of the teeth showed mild resorption, whereas 8% and 19% showed moderate resorption by OPT and CBCT, respectively. Severe resorption was found in only 2 teeth by CBCT. CONCLUSIONS Apical root resorption after orthodontic tooth movement is underestimated when evaluated on OPT. CBCT might be a useful complementary diagnostic method to conventional radiography, to be applied when a decision on continuation or modification of the orthodontic treatment is necessary because of orthodontically induced root resorption.

Pain in orthodontics

This literature review focuses on previous studies of pain and pain perception in dentistry with special emphasis on orthodontic treatment. The prevalence of pain and background factors such as age, gender and culture/society, in addition to pain physiology and the influence of concomitant emotional and cognitive factors, is examined. Pain during orthodontic tooth movement is reported from the point of view of its physiology and character and different assessment methods. These aspects are described both generally and specifically in relation to the type of orthodontic forces and to the experience of discomfort other than pain. Since the orthodontic treatment may cause some degree of suffering for the patients, it is important for orthodontists to handle this situation in the best possible way. Some ideas about the possibilities of avoiding, reducing or alleviating pain in orthodontics are discussed.ZusammenfassungDieser Literaturüberblick beruht auf vorangegangenen Untersuchungen des Schmerzes und der Schmerzempfindung mit besonderer Berücksichtigung der kieferorthopädischen Behandlung. Dabei werden die Häufigkeit des Schmerzes und die Hintergrundfaktoren, wie zum Beispiel Alter, Geschlecht und kulturelle/gesellschaftliche Verhältnisse, sowie die Physiologie des Schmerzes und dessen Einfluß auf begleitende emotionale und kognitive Faktoren dargestellt. Es wird über den Schmerz und dessen Charakter während der orthodontischen Zahnbewegung aus physiologischer Sicht und über verschiedene Bewertungsmethoden berichtet. Diese Gesichtspunkte werden sowohl allgemein als auch speziell abhängig von der Art der angewandten orthodontischen Kräfte und der Erfahrung des Unbehagens wie des Schmerzes beschrieben. Da die kieferorthopädische Behandlung dem Patienten bis zu einem gewissen Grad Leiden verursacht, sollte der Kieferorthopäde mit dieser Situation bestmöglich umgehen. Einige Ansätze zur möglichen Schmerzvermeidung, Schmerzverminderung und Schmerzlinderung in der Kieferorthopädie werden diskutiert.

Histochemical analysis of masticatory muscle in the growing rat after prolonged alteration in the consistency of the diet

Changes in muscle function induce alteration in craniofacial bone growth. To study morphological changes after alteration of masticatory function, NADH-TR reductase and myofibrillar Ca2+-activated ATPase were assessed histochemically, after alkaline and acid pre-incubation, in sections from the anterior deep masseter and the anterior digastric muscles. Type IIA, IIB and transitional fibres of the anterior deep masseter but not of the digastric muscle were smaller in a soft-diet group than in a normal-diet group. There was a small percentage of type IIA fibres and a large percentage of type IIB fibres in the anterior deep masseter in the soft-diet than in the normal-diet group. The elevator muscles do not encounter the same functional demands on a soft as on a normal diet, and this causes different biting and chewing loads, which may in turn induce skeletal changes.

Craniofacial structure in children with juvenile chronic arthritis (JCA) compared with healthy children with ideal or postnormal occlusion

The aim of the present study was to evaluate the influence of condylar destruction on the craniofacial growth of children with juvenile chronic arthritis (JCA) and to compare their craniofacial structure with that of healthy children with ideal or postnormal occlusion. Thirty-five children (7 to 16 years) affected by JCA were compared with 136 children (7 to 16 years) with normal facial structure and occlusion (ideal group) and 62 children (7 to 12 years) with postnormal occlusion (postnormal group). Panoramic radiographs and lateral cephalograms were taken to detect condylar lesions and analyze facial structure. Multiple regression analysis was applied to test the possible relationships between the groups. The present study largely confirms earlier findings that the JCA group has a characteristic craniofacial structure. Their structure differed not only from the facial characteristics of children with ideal, but also to some extent, from children with postnormal occlusion. Furthermore, the craniofacial structure of children with JCA varied greatly, and radiographs showed that the most extreme craniofacial changes, particularly the mandibular structure, were associated with condylar lesions. In conclusion, the arthritic condylar lesions seem to be the main etiologic reason for the altered facial structure and changes in the occlusion in children with JCA. Influences of other factors, such as masticatory muscular function, are also discussed.

Condylar height on panoramic radiographs. A methodologic study with a clinical application.

The aim of this study was to develop and apply a reliable method of measuring the effects of condylar lesions quantitatively on panoramic radiographs. Three different types of machines were tested. Two dry skulls were exposed in six positions in each machine, and the relative size of the condyle in relation to ramus height was calculated. The results showed good validity for the reference points used. The head position did not contribute to the variation in the measurements, but the type of panoramic machine had some influence. It was concluded that the method may be applied when calculating condylar ratios, provided that the same panoramic machine is used. The relative height of the condyle in relation to ramus height was measured bilaterally in three groups of children, with either normal or postnormal occlusion or with juvenile chronic arthritis (JCA), to detect possible asymmetries and define differences in the relative condylar height. The JCA group had a significantly shorter relative condylar height, and asymmetries were commoner than in the other two groups.

Orofacial dysfunction in children and adolescents with myotonic dystrophy

Myotonic dystrophy (DM) is a neuromuscular disorder caused by an expansion of a CTG repeat sequence on chromosome 19q13. The aim of the present study was to describe the characteristics and prevalence of oral motor dysfunction in a cohort of children and adolescents with DM and to correlate different aspects of oral motor function with the type of DM and sex. Fifty‐six individuals with DM (30 males, 26 females; median age 13y 2mo; range 2y 6mo‐21y 5mo) were compared with healthy controls. They were divided into four subgroups: severe congenital DM (n=18); mild congenital DM (n=18); childhood DM (n=18); and classical DM (n=2). A speech‐language pathologist assessed different variables of oral motor function, intelligibility, and lip force. The families used a questionnaire to report on eating difficulties and drooling. All individuals with DM had impaired facial expression. Intelligibility was moderately or severely reduced in 30 patients (60%), excluding six patients without speech. Most had a moderate or severe impairment of lip motility (76.0%), tongue motility (52.2%), and lip force (69.2%), causing deviant production of bilabial and dental consonants. The families reported problems with eating (51.9%) and drooling (37.0%). Oral motor dysfunction was most prominent in congenital DM, and males were more affected than females.

Maxillary molar distalization with noncompliance intramaxillary appliances in Class II malocclusion. A systematic review.

OBJECTIVE To use published data to evaluate quantitatively the dental effects of noncompliance intramaxillary appliances in individuals with Class II malocclusion. MATERIALS AND METHODS A literature search was carried out identifing 13 prospective or retrospective clinical studies matching inclusion criteria. Only appliances with conventional anchorage designs were considered for the review. The data provided in these publications were grouped and analyzed in terms of molar distalization, tipping and vertical movements, and incisor and premolar mesialization, tipping, and vertical movements. RESULTS Maxillary first molars showed distal crown movement and tipping greater than the mesial crown movement and tipping shown by incisors and premolars. Vertical movements of incisors and premolars were in general extrusive, but molars were intrusive or extrusive, depending on the study and the type of appliance used. Appliances that acted palatally seemed to display a smaller distal tipping movement, as well as smaller incisor and premolar mesial tipping movements, when compared with those that acted buccally. Friction-free appliances, namely the pendulum, produced a large amount of mesiodistal movement and tipping, if no therapeutic uprighting activation was applied. CONCLUSIONS Noncompliance intramaxillary molar distalization appliances all act by distalizing molars with a concomitant and unavoidable loss of anchorage, as revealed by incisor and premolar mesial movement. Buccal acting and palatal acting appliances demonstrate almost similar results, with palatal acting appliances showing less tipping. Friction-free palatal acting appliances appear to produce better molar distalizing effects, but with a concomitant notable loss of anchorage.

Short-term anteroposterior treatment effects of functional appliances and extraoral traction on class II malocclusion: a meta-analysis

OBJECTIVE To evaluate the anteroposterior short-term skeletal and dental effects on Class II malocclusion in growing patients following treatment with functional appliances (activators or twin block), extraoral traction, or combination appliances (appliances with both functional and extraoral traction components), based on published data. MATERIALS AND METHODS A literature search was carried out identifying a total of nine prospective clinical trials. The data provided in the publications underwent meta-analysis using the random effects model with regard to SNA, SNB, ANB, and overjet. RESULTS All appliance groups showed an improvement in sagittal intermaxillary relationships (decrease in ANB) when compared to untreated subjects. Activators and twin block appliances accomplish this mainly by acting on the mandible (increases in SNB) while twin block appliances also seem to act on the maxilla (decrease in SNA). Extraoral traction appliances achieve this by acting on the maxilla (decreases in SNA). Combination appliances mainly act on the mandible (increase in SNB). Activators, twin block, and combination appliances also reveal a decrease in overjet, which is not the case in the singular use of extraoral traction. CONCLUSIONS Intermaxillary changes being present in all appliance groups, anteroposterior treatment response following the use of functional appliances and/or extraoral traction in growing class II malocclusion patients is most evident in one of the two jaws (mandible for activators and combination appliances and maxilla for extraoral traction) except for the twin block group, which shows changes on both jaws.

Ultrasonographic thickness of the masseter muscle in growing individuals with unilateral crossbite.

OBJECTIVE To study the bilateral differences in the thickness of the masseter muscles in untreated individuals with lateral crossbite, as well as in subjects with successfully treated functional lateral crossbite, at least three years after the end of treatment. MATERIALS AND METHODS Three groups of growing individuals were studied: (1) untreated group: 38 individuals with unilateral crossbite, (2) control group: 224 subjects without transversal malocclusions, and (3) treated group: 18 individuals with functional lateral crossbite, treated with a quad helix, and at least three years out of retention with all permanent teeth erupted. The thickness of the masseter muscle was measured bilaterally with ultrasonography, using a real time scanner with a 7.5 MHz linear array transducer. RESULTS In the untreated group, the thickness of the masseter muscle on the crossbite side was statistically significantly thinner than the one on the normal side (P = .025). No statistically significant differences were found in the thickness of the masseter muscle between the left and the right side in the control group. In the treated group, no statistically significant differences were found in the thickness of the masseter muscle between the former crossbite side and the normal one. CONCLUSION The masseter muscle in untreated individuals with unilateral crossbite is thinner in the crossbite side when compared to the non-crossbite side possibly due to asymmetric activity of the masticatory muscles. Such an asymmetry in thickness of the masseter muscle could not be detected some years after the successful correction of the crossbite.