Heidrun Kjellberg

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.

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.

Craniofacial growth in juvenile chronic arthritis

The craniofacial growth in children with juvenile chronic arthritis (JCA), especially that of the mandible, and the degree of destruction of the mandibular condyles vary depending on the heterogeneity in duration and intensity of the disease. In JCA children showing destruction of the temporomandibular joint, the dentofacial morphology is characterized by overall smaller dimensions of the mandible, mandibular retrognathia, a steep mandibular plane, Class II malocclusion, dental crowding, and frontal open bite. In children with unilateral condylar destruction, asymmetries will develop, with the chin deviating to the affected side. The facial morphology of JCA children with condylar lesions becomes more abnormal during growth, reflecting a decelerated mandibular development and a backward-rotating growth pattern. The main single cause of the deviating craniofacial growth is mandibular condylar destruction. Other factors that may influence the craniofacial growth are head posture, soft tissue stretching, disease activity and drug therapy, type of onset of the disease, muscle weakness, decreased functional ability, and orthodontic treatment.

Caries Risk Profiles in Orthodontic Patients at Follow-Up Using Cariogram

OBJECTIVE To analyze caries-related factors shortly after orthodontic treatment and to use the Cariogram computer program to describe caries risk profiles at follow-up in these patients. MATERIALS AND METHODS One hundred orthodontic patients age 12-29 years, with a mean age of 17.5 years, were included in the study. They were divided into two groups (50 in each) based on their prebonding decayed, filled surfaces index (DFS). High (5 > or = DFS) and low (2 < or = DFS) groups were created. All patients were examined after debonding in the following order: interview, plaque score, caries examination, saliva samples, bitewing radiographs, panoramic radiographs, and intra-oral digital photos. All types of carious lesions in both the enamel and dentine were diagnosed clinically and radiographically and included in the DFS index. A paraffin-stimulated whole saliva sample was collected for estimations of secretion rate, buffer capacity, and number of mutans streptococci and lactobacilli. RESULTS The low caries group (2 < or = DFS) displayed a statistically significant difference and low values for the following factors, DFS (P < .001), lactobacilli (P < .001), mutans streptococci (P < .001), and high Cariogram percent (P < .001). The plaque index displayed very close significance (P = .051). CONCLUSIONS Patients with high (5 > or = DFS) numbers before orthodontic treatment ran a higher risk of developing caries. They had significantly higher numbers of mutans streptococci and lactobacilli and had less chance of avoiding new cavities according to the Cariogram.

Impaction and retention of second molars: diagnosis, treatment and outcome. A retrospective follow-up study.

OBJECTIVE To evaluate treatment outcome in patients with second molar impaction and retention. MATERIALS AND METHODS A total of 135 second molars, 65 in the maxilla and 70 in the mandible were collected from 87 patients (45 girls and 42 boys) with a mean age of 15 years (range: 11- 19 years). Available patient records, x-rays, study casts, and photos were studied. The mean follow-up period was 22 months (range: 4-106 months). RESULTS A total of 166 second molars were diagnosed as impacted, 24 as primary and 5 as secondarily retained; 80% of the second molars were orthodontically or surgically treated. In more than half of the treated patients the second molars failed to erupt into a proper position. Surgical exposure of the retained or impacted second molar was the treatment found most successful (71%). The least successful treatment (11%) used the third molar to replace the second molar after the second molar was extracted. No clear difference in treatment outcome could be detected between the impacted and the primary or secondary retained teeth. However, a clear difference was found between the impacted and the primary retained second molars regarding treatment strategy: 9% of the impacted and 67% of the primary retained teeth were left untreated. Dental crowding was found in 70% of the patients. CONCLUSION In more than half of the treated patients the second molars failed to erupt into a proper position. The most common treatment given (extraction of the second molar) was the least successful.

Relapse tendency after orthodontic correction of upper front teeth retained with a bonded retainer.

OBJECTIVE To investigate the amount and pattern of relapse of maxillary front teeth previously retained with a bonded retainer. MATERIALS AND METHODS The study group consisted of 135 study casts from 45 patients. Recordings from study models before treatment (T1), at debonding (T2), and 1 year after removal of the retainer (T3) were present. All patients had been treated with fixed edgewise appliances. The irregularity index (sum of contact point displacement [CPD]) and rotations of front teeth toward the raphe line were calculated at T1, T2, and T3. RESULTS The mean irregularity index at T1 was 10.1 (range 3.0-29.9, SD 5.4). At T2 it was 0.7 (range 0.0-2.1, SD 0.7), and at T3 it was 1.4 (range 0.0-5.1, SD 1.2). Fifty-five teeth in 42 patients were corrected more than 20 degrees between T1 and T2 (mean correction 31.4 degrees range 20.0-61.7), and mean relapse in this group was 7.3 degrees (range 0.0-20.5). Regarding alignment of the maxillary front teeth, the contact relationship between the laterals and centrals seems to be the most critical. A significant positive correlation was found between the amount of correction of incisor rotation and the magnitude of relapse but not between the amount of correction of CPD and the magnitude of relapse. Eighty-four percent of the overcorrected CPDs returned to a desired position. CONCLUSIONS Minor or no relapse was noted at the 1-year follow-up.

Masseter muscle thickness and mechanical advantage in relation to vertical craniofacial morphology in children

Objective. To investigate the relationship between vertical craniofacial morphology and masseter muscle thickness and mechanical advantage in children. Material and methods. The sample comprised 72 children (36 F, 36 M), 8.5–9.5 years of age, with various malocclusions and no previous orthodontic treatment. The thickness of the masseter was measured bilaterally by means of ultrasonography, and the recordings were performed both in relaxation and under contraction. Mechanical advantage was measured on the lateral cephalograms as the ratio between the masseter moment and the bite force moment arms. Two linear ratios and three angular measurements were used to describe vertical craniofacial morphology. Results. The mean masseter thickness was greater in the male group (p<0.05) in both relaxed and contracted conditions. There were no significant sex differences for the mechanical advantage or for the measurements of vertical craniofacial morphology. In females, there is a positive association between masseter muscle thickness and its mechanical advantage. Multiple regression analysis showed a positive association between posterior to anterior facial height ratio in both genders and a negative association between masseter thickness and the intermaxillary angle in females. Conclusions. There is a significant association between posterior to anterior facial height and the masseter muscle in children. The importance of the masseter muscle is more evident in the vertical facial morphology of females.

A systematic review of the interceptive treatment of palatally displaced maxillary canines

The aim of this study was to assess whether interceptive treatment in the mixed dentition prevents impaction of palatally displaced canines (PDC) by systematically reviewing the literature. A literature search of PubMed, the Cochrane Library electronic databases, and Scopus was performed covering the period from January 1966 to May 2009. The inclusion criteria were mixed dentition with unilateral or bilateral PDC, randomized controlled trials (RCT), prospective and retrospective studies with untreated controls, and clinical trials comparing at least two treatment strategies. Three reviewers selected and extracted the data independently and evaluated the quality of the studies. Inter-examiner reliability was measured using the intraclass correlation coefficient (ICC). The search strategy resulted in 686 articles, of which two met the inclusion criteria. Because of the unequivocal results and heterogeneity in the study methods, the scientific evidence was too weak to fully evaluate the effect that interceptive treatment might have on PDC and which treatment modalities are most effective. The quality of the studies was rated as low because of inadequate sample selection and deficient description of sample size, confounding factors, uncertainty of randominization, and no blinding in measurements. The ICC value for total scores was >0.80, e.g. perfect agreement. To obtain reliable scientific evidence as to whether interceptive treatment prevents impaction of PDC and which treatment modalities are the most effective, better controlled and well-designed RCTs are needed. Future studies should also include assessment of patient satisfaction and pain experience as well as analysis of the costs and side-effects of treatments.

Combination of high-fluoride toothpaste and no post-brushing water rinsing on enamel demineralization using an in-situ caries model with orthodontic bands

Abstract Objective. To compare the effects on enamel demineralization and fluoride (F) retention of two different brushing–rinsing regimens. Material and methods. An in-situ caries model with orthodontic bands was used for 8–9 weeks. A total of 20 orthodontic patients participated. They were randomized into two groups: (1) a test group using 5000 ppm F (n = 10) with no post-brushing water rinsing; and (2) a control group using 1450 ppm F (n = 10) with three sessions of post-brushing water rinsing. Orthodontic stainless-steel bands were applied to the two upper first premolars, leaving 2–3 mm of space away from the exposed buccal surface in order to accumulate plaque and provoke initial caries development. The teeth were extracted after 8 and 9 weeks, then analysed using quantitative light-induced fluorescence (QLF). Additionally, oral F retention was compared for the two groups. Results. In comparison to the control group, the test regimen resulted in a non-significant smaller QLF lesion area and a significantly lower average QLF loss of fluorescence (P < 0.05). The highest F retention concentration under the band was found in the test group (P < 0.001). Conclusions. The combination of using a 5000 ppm F toothpaste and no post-brushing water rinsing had a greater anti-caries potential and resulted in elevated oral F retention compared to a 1450 ppm F toothpaste with three sessions of post-brushing water rinsing.