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Biomedical subjects

J Ahlgren

Publications and source records attributed to J Ahlgren.

At least 19 recordsLinked to original sources
PubMed1996

Effects of buccal shields on the maxillary dentoalveolar structures and the midpalatal suture--histologic and biometric studies in rabbits.

The mechanism of the buccal shields with regard to regulating the transversal relationship of the maxillary dental arch is uncertain. The periosteal pull theory, growth at the midpalatal suture and changes in equilibrium have all been proposed as explanatory factors. The aim of the study was to investigate the transversal development of the dental arch and the osseous remodeling at the lateral surfaces of the maxillary alveolar process and in the midpalatal suture after stretching the bucca (cheek) with buccal shields in the vestibulum. Ten New Zealand white male rabbits 12 weeks old were used. The animals were divided into two groups (control and experimental). Initial and final impression had been taken from the two groups and plaster models were made using biometric analysis in all animals of each group. Transversal measurements were taken of the distances between the maxillary right and left teeth. Tetracycline hydrochloride and Alizarin complexone were used to label the mineralizing tissues. After the animals had been killed, the biopsies from the midpalatal suture, the alveolar wall, and the periosteum were studied under a microscope. The results from the biometric analysis showed maxillary dental arch expansion in the two groups that was significantly larger in the experimental group. Microscopically, the growth at the midpalatal suture was also significantly larger in the experimental group, while no significant differences were found at the maxillary alveolar bone in the two groups. The conclusions drawn from this study are that the vestibular buccal shields bring about an increased expansion of the maxillary dental arch and increased growth at the midpalatal suture. No increased bone deposition was found at the buccal dentoalveolar wall, inducing doubts as to the accuracy of the periosteal pull theory for widening of the dental arch.

Activator Appliances↗
PubMed1995

EMG studies of lip and cheek activity in sucking habits.

Pronounced lip and mentalis (perioral) muscle activity was developed during thumb and dummy sucking. Cheek (Buccinator) activity was less evident, showing light to moderate activity. Lip and cheek activity was more noticeable during dummy sucking than thumb sucking. Sucking water through a straw and swallowing produced similar functional patterns to thumb sucking: strong lip and mentalis activity but comparatively low buccinator activity. Activity at rest in perioral muscles was pronounced among thumb and dummy suckers, while buccinator activity was negligible. Lip and cheek activity was substantially less, both at rest and during sucking, in a control group of children who were not thumb suckers.

Adolescent↗
PubMed1994

Jaw-closing muscles: electromyographic activity of human subjects with reduced periodontal support.

The aim of this study was to compare the electromyographic (EMG) activity of jaw-closing muscles of individuals with normal and reduced periodontal bone support. Fourteen adult subjects with more than 24 remaining teeth and low levels of periodontal inflammation, were selected for the study. Subjects of the control group had 90% of the periodontal bone support left, while other subjects presented a reduction of 52% of the original periodontal bone. Chewing experiments were performed using silicone tablets, carrots and white bread. The EMG of masseter and anterior temporal muscles was performed bilaterally, using bipolar surface electrodes, and the EMG amplitude was full wave rectified, integrated and the area extension under the curve was used to access muscle activity. The results of the chewing experiments did not show any statistically significant difference in the EMG activity of the study groups, irrespective of the chewing stuff. The height of periodontal bone support did not seem to influence the electroactivity of jaw-closing muscles, indicating that reduced periodontal support might equally be able to withstand masticatory loads. Hence, individuals with reduced periodontal bone support revealed a similar EMG activity compared to subjects with normal periodontal bone support.

Alveolar Bone Loss↗
PubMed1994

Prediction of axillary lymph node metastases in a screened breast cancer population. South-East Sweden Breast Cancer Group.

To define a subgroup of patients, in whom axillary dissection could be omitted, we analysed the frequency of pathologically confirmed lymph node metastases depending on tumour size, hormonal receptors, DNA ploidy, S-phase fraction (SPF), and clinical nodal status among 1,145 patients with stage I-II breast cancer from an area with ongoing screening. Clinical nodal status and tumour size were strongly correlated to pathological nodal status. Also SPF > 10% was strongly correlated to node positivity in univariate analysis. In multivariate analysis there was still a significant correlation among cases with tumour size < or = 20 mm. In conclusion, patients with clinically negative nodal status, and tumour size < or = 20 mm and < or = 10 mm had pathologically positive nodes in 25% and 15% of cases respectively. The addition of SPF did not lower these figures significantly since small tumours with high SPF are few.

Adult↗
PubMed1993

Three-stage activator treatment of a severe skeletal Class II, open bite malocclusion.

Activator therapy for a severe Class II, Division 1 malocclusion with open bite malocclusion is described. The treatment was performed in three stages: one, "early-early," at the age of 5 to 6 years; one "early," between 9 and 11 years; this was followed by 2 years of retention with a maxillary retainer. The patient continued to be observed further over a 3-year period. The final records show a normal, stable occlusion, and good facial balance.

Activator Appliances↗
PubMed1993

A ten-year evaluation of the quality of orthodontic treatment.

A 10-year evaluation of the quality of orthodontic treatment at the Department of Orthodontics, School of Dentistry in Malmö, University of Lund, showed that in approximately 3 cases out of 4 (73%) successful results were noted in the malocclusions under treatment. In approximately half the cases the ideal treatment goal, normal occlusion, was achieved. The treatment was unsuccessful in 12% and in a large group of patients (15%) the treatment was discontinued due to lack of motivation or compliance. More accurate study and documentation of subjective need of treatment (motivation, cooperation and social sufficiency) would improve the quality of orthodontic care and make it more efficient. Some sort of penalty due to distinct lack of patient cooperation might improve orthodontic care. Root resorption occurred frequently during orthodontic treatment with multiband fixed appliances, but the apical shortening was small and without clinical significance.

Adolescent↗
PubMed1992

Muscle response to the oral-screen activator. An EMG study of the masseter, buccinator, and mentalis muscles.

The myofunctional changes that occur during orthodontic treatment with functional appliances constructed with vestibular screen elements, such as buccal shields and lip pads, have not been sufficiently investigated. The aim of this study was to examine electromyographically the response of the masseter, buccinator and mentalis muscles to the oral-screen activator (OSAC), which is a conventional activator constructed with buccal shields and lip pads. The material consisted of 10 children, with Angle Class II, division 1 malocclusion and narrow dental arches (mean age 10.7 years), treated at the Department of Orthodontics, School of Dentistry, Malmö, Sweden. The group had a mean overjet of 8.5 mm, and a mean ANB angle of 6 degrees. Six out of the 10 cases had incompetent lips at relaxed lip position. The construction bite of the OSAC was taken with the anterior teeth in edge-to-edge position. The recording procedure included the following positions: (a) postural position of the mandible with lips relaxed and lips closed; (b) clenching; (c) swallowing saliva; and (d) spatula exercise. EMG recordings were made after 1, 2, and 3 months of appliance treatment. Differences between means were tested with a two-way analysis of variance (ANOVA). The results showed that during postural position with lips closed there was a statistically significant increase in mentalis EMG with the oral-screen activator in place. The buccinator and masseter muscles showed no EMG activity during rest with or without the appliance in the mouth. During clenching we found no statistically significant difference in masseter EMG with or without the appliance in place. During swallowing saliva a statistically significant decrease was recorded in mentalis EMG with the oral-screen activator in the mouth, while buccinator activities remained the same with and without the appliance. The masseter activity, on the other hand, increased significantly with the activator in place. During spatula exercise mentalis and buccinator were highly activated. The conclusions drawn from this study are that the oral screen activator (OSAC) increased masseter activity during swallowing, but it remained unchanged during clenching. Lip pads increase mentalis activity during lip closure, but reduce mentalis hyperactivity during swallowing. The buccinator activity was insignificant and buccal shields did not change that activity. Spatula exercise stimulates both mentalis and buccinator activity.

Acrylic Resins↗
PubMed1991

Continuous infusion 5-fluorouracil plus weekly cisplatin for pancreatic carcinoma. A Mid-Atlantic Oncology Program study.

Fifty-six previously untreated patients with biopsy-proven, locally advanced or metastatic and measurable adenocarcinoma of the pancreas were treated with the combination of a protracted intravenous infusion of 5-fluorouracil (5-FU) and low dose weekly bolus cisplatin administered continuously for 10 weeks followed by a 2-week rest period. The objective response rate was 16% with two patients (4%) achieving a complete response (confidence intervals, 8% to 29%). The median survival time for all treated patients was 5.8 months; however, 26% of all patients were alive at 1 year. Both median survival time and the proportion alive at 1 year exceed that of prior reports involving large patient groups, possibly due to better patient selection.

Adenocarcinoma↗
PubMed1987

A comparison of electromyography recorded parallel and transverse to the fibres of the anterior and posterior temporalis muscle in man.

Electrical activity recorded during voluntary clenching by platinum hook intra-cutaneous electrodes was significantly higher (p less than 0.01) when the electrodes were placed parallel to the muscle fibres than across the fibres. The correlation between the parallel and transverse EMG recordings was highly significant (p less than 0.001).

Action Potentials↗
PubMed1985

An electromyographic analysis of the temporalis function of normal occlusion.

Electromyographic (EMG) activity was recorded from the anterior, middle, and posterior regions of the temporalis muscle in ten subjects with normal occlusion of the teeth and with the mandible at rest and during exertion of increased biting force, using bipolar intramuscular electrodes. Results show that the posterior part of the temporalis muscle maintains the mandibular posture. Although there is no statistically significant difference in EMG recordings between the three divisions of the temporalis muscle during intercuspal biting, individual variations in EMG pattern exist. During exertion of increased biting force the EMG activity increases proportionally in all parts of the muscle. During retruded biting force the posterior temporalis predominates. The EMG activity of the temporalis muscle is correlated to the form and position of the mandible.

Action Potentials↗
PubMed1982

Changes in length and torque of the masticatory muscles produced by the activator appliance. A cephalometric study.

The purpose of this study was to measure cephalometrically the change in muscle length and torque of the masticatory muscles produced by an activator appliance. The study was based on 10 orthodontic cases with distoclusion. Muscle length and force arm (leverage) were measured on two lateral cephalometric roentgenograms of each subject, one with the teeth in centric occlusion and one with an activator between the teeth. The construction bite of the activator was taken with the mandible repositioned 2-3 mm below and 5-6 mm ahead of resting position. It was found that the temporal masseter and medial pterygoid muscles increased 5-15% in length whereas the lateral pterygoid decreased 25% in length with the activator in place. The effect on the force arm on the temporal muscle was small, a decrease of 3-6%, but that on the masseter was much more dramatic, a decrease of 21-22%. Thus, as far as the torque of the temporal muscle is concerned, the small decrease in force arm is well compensated for by the increased muscle tension due to the stretching by the activator. The clinical significance of the findings for obtaining the best construction bite of the activator is discussed.

Activator Appliances↗