Biomedical subjects

A Isberg

Publications and source records attributed to A Isberg.

At least 19 recordsLinked to original sources

PubMed2006

Bilateral TMJ disk displacement induces mandibular retrognathia.

Unilateral non-reducing TMJ disk displacement has been shown to retard mandibular growth on the ipsilateral side, with facial asymmetry a sequela. We hypothesized that bilateral affliction would impair mandibular growth bilaterally, generating mandibular retrognathia. Non-reducing TMJ disk displacement was surgically created in 10 growing New Zealand White rabbits. Ten additional rabbits served as a sham-operated control group. Facial growth was followed in serial cephalograms, with tantalum implants, during a period corresponding to childhood and adolescence in man. The results verified that bilateral non-reducing TMJ disk displacement retarded mandibular growth bilaterally, the extent corresponding to mandibular retrognathia in man. Maxillary growth was also retarded, but to a lesser degree. Growth impairment fluctuated over time, the most striking retardation occurring during periods of general growth acceleration. This should be taken into consideration when orthodontic treatment, aimed at stimulating mandibular growth, is initiated in adolescent individuals with non-reducing TMJ disk displacement.

Animals↗

PubMed2004

Virtual reality for simulation of radiographic projections: validation of projection geometry.

OBJECTIVE: To develop a software for virtual reality (VR) simulation of X-ray images based on perspective projections through a patient model derived from data from a CT examination and to evaluate the accuracy in the projection geometry obtained by the software. METHODS: A VR software was developed on a personal computer, with models of a patient, an X-ray machine and a detector. The model of the patient was derived from data from a CT examination of a dry skull. Simulated radiographic images of the patient model could be rendered as perspective projections based on the relative positions between the models. The projection geometry of the software was validated by developing an artificial CT data set containing high attenuation points as objects to be imaged. The accuracy in projection geometry was evaluated in a systematic way. The distances between two dots, representing the projected test points in the simulated radiographic images, were measured. They were compared with theoretical calculations of the corresponding distances using traditional mathematical tools. RESULTS: The difference between the simulated and calculated projected distances never exceeded 0.5 mm. The error in simulated projected distances was in most cases within 1%. No systematic errors were revealed. CONCLUSION: The software, developed for personal computers, can produce simulated X-ray images with high geometric accuracy based on perspective projections through a CT data set. The software can be used for simulation of radiographic examinations.

Computer Simulation↗

PubMed2003

Snoring, sleep apnoea and swallowing dysfunction: a videoradiographic study.

OBJECTIVES: Snoring is associated with subclinical pharyngeal swallowing dysfunction, probably owing to vibration trauma to the pharyngeal tissues caused by snoring. Negative intrathoracic pressure during apnoea causes stretching of the velum and pharynx. The aim of this study was to investigate whether patients with severe sleep apnoea have an increased frequency of videoradiographically diagnosed subclinical pharyngeal swallowing dysfunction compared with snoring patients with or without mild sleep apnoea as well as with non-snoring controls. METHODS: Eighty consecutive patients referred for sleep apnoea recordings because of snoring were examined. Fourteen of these patients were excluded because they suffered from dysphagia. Fifteen non-snoring, non-dysphagic volunteers served as controls. Videoradiography was performed to examine the oral and pharyngeal swallowing function in patients and controls. Overnight sleep apnoea recordings were used to evaluate the apnoea-hypopnoea index (AHI). RESULTS: Pharyngeal swallowing dysfunction was observed in 34/66 (52%) of the snoring patients and in 1/15 (7%) of the non-snoring controls. Pharyngeal swallowing dysfunction was observed in 50% of patients with an AHI of >or=30, in 61% of patients with an AHI of 5-29 and in 43% of patients with an AHI of <5. There was no significant difference in the frequency of pharyngeal swallowing dysfunction between snoring patients with different AHIs. CONCLUSION: Snoring patients run an increased risk of developing subclinical pharyngeal swallowing dysfunction independent of concomitant sleep apnoea.

Adult↗

PubMed2000

Validity of identification of gonion and antegonion in frontal cephalograms.

This study was designed to develop a method of transferring gonion from lateral to frontal cephalograms, and to use this method as gold standard when evaluating observer performance in identifying gonion in frontal cephalograms. Observer ability to identify antegonion was also evaluated. There was a range of 28 mm in the observers' identification of gonion and a statistically significant deviation from gold standard. The factors "observer" and "cephalogram," regarded as random effects in an ANOVA analysis, and their interaction, each influenced the result, P < .001. The deviation from the mean of all observations for antegonion ranged 8 mm with "cephalogram" having a statistically significant influence. The results suggest that neither gonion nor antegonion can be routinely used as valid landmarks in frontal cephalograms. Gonion can, however, be used if first identified in a lateral cephalogram and transferred to a paired frontal cephalogram aided by radiographic indicators combined with a bilateral scrutiny of projection geometry in different planes through gonion and indicator.

Analysis of Variance↗

PubMed2000

Deterioration of intraoral recognition of shapes after treatment of oral and pharyngeal cancer.

Thirty patients with diagnosed malignant tumors of the oral cavity or pharynx were tested in regards to intraoral shape recognition at 4 test occasions: before all treatment, after radiotherapy, 6 months after surgery, and 1 year after surgery. They were compared within groups as well as with a group of healthy reference individuals of the same age who underwent the same test procedure at a 2-month interval. The tumor itself did not influence the capability of shape recognition. The reference individuals demonstrated significantly better results on the second test occasion, which is known as a learning effect. Learning improvement was not seen in the patients whose second test occasions were after radiotherapy, implying an impediment amounting to the magnitude of the learning effect. At 6 months after surgery the patients' capabilities of shape recognition had deteriorated significantly with no difference between the oral cancer group and the pharyngeal cancer group. No spontaneous rehabilitation had taken place 1 year after surgery. The presence or absence of surgical lingual nerve damage did not influence the results. The nonoperated side does not compensate for the operated one. It is plausible that decreased oral sensory acuity in recognizing the shape of the bolus contributes to postoperative swallowing problems.

Adult↗

PubMed2000

Swallowing dysfunction related to snoring: a videoradiographic study.

Biopsy studies of the soft palatal and oropharyngeal tissues in habitual snorers and patients suffering from obstructive sleep apnoea have shown signs of neurogenic lesions. These lesions might affect the pharyngeal swallowing function, which is dependent on adequate sensitivity. The objective of the present study was to test the hypothesis that snoring is associated with aberrant pharyngeal swallowing function. Forty-one consecutive patients without dysphagia, seeking medical attention because of heavy snoring and various degrees of daytime sleepiness, were prospectively selected. Fifteen non-snoring volunteers without dysphagia served as controls. Patients and volunteers were videoradiographically examined in lateral and posteroanterior views during the oral and pharyngeal phases of swallowing. The hypothesis was verified. Snoring patients demonstrated deviant pharyngeal swallowing function seven times more frequently than did the non-snoring volunteers. Deviant pharyngeal swallowing function was observed in 22 (54%) of the snorers compared with 1 (7%) of the non-snoring volunteers. Impaired bolus control with premature leakage of bolus into the pharynx and a delayed evocation of the swallowing reflex was the most common finding, followed by bolus residual in the pharynx and laryngeal penetration. The conclusion was that snoring is associated with subclinical pharyngeal swallowing dysfunction.

Adult↗

PubMed1999

Mandibular length and midline asymmetry after experimentally induced temporomandibular joint disk displacement in rabbits.

The purpose of the present investigation was to test the hypothesis that permanent disk displacement in the temporomandibular joint (TMJ) is one causal factor in the development of mandibular midline asymmetry. Unilateral, nonreducing disk displacement was therefore created in growing rabbits. The right TMJ in seven experimental animals was surgically opened, and the disk was anteriorly displaced with the posterior disk attachment kept intact above the condyle. The right TMJ in seven sham animals was surgically opened and closed without any disk manipulation. Seven additional rabbits served as reference animals. For identification of mandibular growth, tantalum implants were inserted into the mandibular body, and lateral cephalograms were exposed at the beginning and at the end of the experimental period. After the animals had been sacrificed, the mandibles were dissected and measurements were performed on the mandibular specimens. Axial radiographs of the mandibles were then exposed and measurements of mandibular length and midline shift were performed in the radiographs. The mandible in the experimental animals was consistently shorter on the disk displacement side resulting in a midline shift to the ipsilateral side. No mandibular asymmetry was observed in the sham and reference groups. The hypothesis was verified; disk displacement in the TMJ with an onset during the growth period can cause mandibular length and midline asymmetry in growing rabbits.

Analysis of Variance↗

PubMed1999

Prevalence of temporomandibular joint disk displacement in infants and young children.

OBJECTIVE: The purpose of this study was to determine the prevalence of temporomandibular joint disk displacement in infants and young children. STUDY DESIGN: Magnetic resonance images were obtained of the temporomandibular joints in 30 infants and young children ranging in age from 2 months to 5 years (median age, 3 years; mean age, 2.5 years). RESULTS: All joints had normal superior disk position. The computed 95% confidence interval was 0.00-0.06, which implies a minimal probability that disk displacement would occur in this age group. CONCLUSIONS: The result contradicts previous suggestions that temporomandibular joint disk displacement could represent a congenital normal anatomic variant.

Argentina↗

PubMed1999

Thickness of the articular soft tissue of the temporal component in temporomandibular joints with and without disk displacement.

OBJECTIVE: The purpose of this investigation was to test the hypothesis that temporomandibular joint disk displacement is associated with significant functional adaptive changes of the articular soft tissue of the articular eminence. STUDY DESIGN: Thirteen temporomandibular joint autopsy specimens with normal superior disk position and 12 with complete anterior disk displacement were cryosectioned, and sections were stained and photographed. At a magnification of x20 the soft tissue was measured (1) at the inflection point, (2) on the posterior slope, (3) at the apex, and (4) on the anterior slope of the articular eminence. RESULTS: Displacement of a deformed or nondeformed temporomandibular joint disk without perforation of the posterior disk attachment was associated with significantly increased thickness of the articulating soft tissue at the apex and on the posterior and anterior slopes of the articulating eminence. When disk displacement was associated with a perforation of the posterior disk attachment, the soft tissue was not significantly thicker than in joints with normal superior disk position. CONCLUSIONS: Increase in articulating soft tissue thickness is interpreted as an adaptive mechanism to maintain the condyle path and withstand excessive loading at interposition of the temporomandibular joint components. When the plasticity of the tissues is surpassed, the adaptation will be thwarted and replaced by tissue breakdown.

Adult↗

PubMed1999

Temporomandibular joint condyle changes after surgically induced non-reducing disk displacement in rabbits: a macroscopic and microscopic study.

Experimentally induced displacement of the temporomandibular joint (TMJ) disk has previously been shown to induce shortening of the mandibular ramus on the ipsilateral side. The aim of this investigation was to reveal whether this shortening develops due to primary influence on condyle growth or by secondary loss of condyle mass due to degenerative tissue breakdown. Disk displacement was created in the right TMJ in seven 3-month-old rabbits, the posterior disk attachment kept intact. Seven rabbits underwent surgical opening of the TMJ without disk intervention. Seven additional animals served as references. After a 3-month experimental period, the animals were sacrificed. Previous analysis revealed shortening of mandibular height and length caused by ipsilateral TMJ disk displacement. The condyles were examined macroscopically and by histologic sectioning or scanning electron microscopy. All condyles were covered with smooth articulating soft tissue and without visible signs of degenerative changes. Four condyles from joints with disk displacement demonstrated substantial regressive remodeling resulting in a change of condyle shape with forward/downward rotation of an enlarged articulating surface. It was concluded that TMJ disk displacement in a growing individual can induce reduction of mandibular height and length before a stage where visible osteoarthrotic changes develop. It implies a primary adverse effect on condyle growth.

Animals↗

PubMed1999

Deterioration of intraoral hole size identification after treatment of oral and pharyngeal cancer.

Thirty-one patients with a diagnosed malignant tumour of the oral cavity or pharynx were tested in hole size identification on four test occasions: before all treatment, after radiotherapy and 6 months and 1 year after surgical treatment. They were compared within groups as well as with a group of healthy reference individuals of the same age who underwent the same test procedure at a 2 months' interval. The oral group did not decline in hole size identification after radiotherapy, but did after surgery. The deterioration was persistent 1 year after surgery. The pharyngeal group did not change performance in hole size identification after radiotherapy, nor after surgery. It is obvious that surgery of the oral structures causes the deterioration. No correlation with damage to the lingual nerve could be registered. The oral cavity reacts as one unit, despite sensory input from two sides. The non-operated side does not compensate for the operated side. It is plausible that decreased oral sensory acuity, in recognizing hole size of the bolus, contributes to postoperative swallowing problems.

Adult↗

PubMed1999

Persisting dysphagia after uvulopalatoplasty performed with steel scalpel.

OBJECTIVES/HYPOTHESIS: The aim of the present study was to determine the incidence of postoperative persisting dysphagia after uvulopalatoplasty performed with conventional steel scalpel (UPP) and to videoradiographically evaluate the oral and pharyngeal phases of swallowing in patients reporting persisting dysphagia. The hypothesis to be tested was that patients treated with UPP would demonstrate a lower incidence of persisting dysphagia than previously found after uvulopalatoplasty performed with laser technique (LUPP). STUDY DESIGN: Retrospective. METHODS: Sixty-eight of 76 consecutive patients treated with UPP answered a questionnaire concerning outcome and late complications after the operation. The patients who reported postoperative dysphagia were additionally interviewed at a minimum of 1 year postoperatively, and the oral and pharyngeal phases of swallowing were videoradiographically examined in those with persisting dysphagia. RESULTS: The incidence of persisting dysphagia after UPP was 29%. Videoradiographically 71% of the dysphagic patients showed a deviant pharyngeal swallowing pattern. CONCLUSION: The incidence of persisting dysphagia after UPP did not differ from that reported after laser uvulopalatoplasty. Dysphagia after UPP was mostly associated with videoradiographic signs of deviant pharyngeal swallowing function. Patients should be informed that there is a risk of developing dysphagia after uvulopalatoplasty.

Adult↗

PubMed1999

Comparison between two types of pharyngeal flap with regard to configuration at rest and function and speech outcome.

OBJECTIVE: In management of hypernasality, wide pharyngeal flaps have been advocated when pharyngeal wall adduction is limited. Pharyngeal flaps merged into a transversely split velum (TS flaps) are reported to be wider than if the velum is split in the midline (MS flaps). The hypothesis to be tested was that TS flaps are wider than MS flaps and are more caudally based. DESIGN: In this prospective study, MS flaps were videoradiographically and nasopharyngoscopically compared with TS flaps at both rest and function. Pharyngoplasty was randomly performed by one of three surgeons and the radiographic examinations were carried out by one radiologist. The speech was assessed pre- and postoperatively. SETTING: The Stockholm Cleft Palate Team, Sweden, treated all patients. PATIENTS: After strict selection of the patients to avoid any uncontrolled impact on velopharyngeal sphincter function, 22 patients with limited pharyngeal adduction received TS flaps and 20 patients with good adduction received MS flaps. RESULTS: The data failed to show any difference in location of flap base and in flap width at rest. During function, TS flaps demonstrated statistically significant widening of the flap base. TS flaps, but not MS flaps, often had a bulge that appeared to assist velopharyngeal closure in some patients. Speech evaluation revealed that both flap types corrected velopharyngeal insufficiency equally well. CONCLUSIONS: TS flaps were not wider than MS flaps, and functional plasticity of the TS flap appeared essential for elimination of velopharyngeal insufficiency. Contribution of postoperative adaptation of the pharyngeal wall adduction remains to be clarified.

Adolescent↗

PubMed1999

Adaptation of pharyngeal wall adduction after pharyngeal flap surgery.

OBJECTIVE: The purpose of this investigation was to study lateral pharyngeal wall adduction relative to pharyngeal flaps of different widths. The hypothesis to be tested was that pharyngeal wall adduction does not increase postoperatively but may decrease due to the mechanical hindrance of a wide flap. DESIGN: In this prospective study, adaptation of lateral pharyngeal wall adduction during speech was studied relative to pharyngeal flaps of different widths utilizing videoradiography. Flap width was determined nasopharyngoscopically. SETTING: All patients were treated by the Stockholm Cleft Palate Team, Sweden. PATIENTS: Fifty-three patients were strictly selected by discarding conditions known to exert uncontrolled influence on velopharyngeal sphincter function. RESULTS: The results revealed a potential for adaptation of pharyngeal wall adduction to different flap widths. The magnitude and character (increase or decrease) of change in adduction was significantly correlated with the degree of preoperative adduction and with the width of the flap. In patients with limited preoperative adduction, pharyngeal wall activity increased, more in the presence of a narrow flap while less if the flap was wide. When preoperative adduction was pronounced, the postoperative activity decreased because of mechanical hindrance by the flap, and the degree of impediment was correlated to the width of the flap. CONCLUSION: A potential for increased lateral pharyngeal wall adduction after pharyngeal flap surgery was verified, but the result cannot be interpreted as generally applicable because of the strict selection of patients.

Adaptation, Physiological↗

PubMed1998

The effect of age and gender on the onset of symptomatic temporomandibular joint disk displacement.

OBJECTIVE: The aim of this study was to test the hypotheses that incidence of symptomatic temporomandibular joint disk displacement is evenly distributed over all ages and between genders and that there is no gender difference in pain perception. STUDY DESIGN: The study population consisted of 248 consecutive patients with radiographically verified symptomatic temporomandibular joint disk displacement. The time of onset of the condition relative to age and gender was determined, as was pain level. RESULTS: There was a statistically significant peak in incidence of symptomatic temporomandibular joint disk displacement during adolescence for both genders. Teenage girls were found to run a risk of developing disk displacement that is three times greater than the risk for teenage boys, and girls were found to run a risk during puberty that is four times greater than their risk later in life. The age at onset of the condition did not differ between genders. Both female and male subjects reported the same degree of pain level. CONCLUSION: The results point to a teenage preponderance and a sexual dimorphism with respect to incidence of symptomatic temporomandibular joint disk displacement.

Adolescent↗

PubMed1998

Steepness of articular eminence and movement of the condyle and disk in asymptomatic temporomandibular joints.

OBJECTIVE: The purpose of this study was to investigate the rotational motion characteristics of the disk-condyle complex in relation to the steepness of the articular eminence of the normal temporomandibular joint. STUDY DESIGN: We studied 14 asymptomatic volunteers with normal temporomandibular joints using magnetic resonance images with gradient recoil acquisition in the steady state. The degree of condyle and disk rotation within the glenoid fossa, the inclination of the condyle path, and the steepness of the articular eminence were measured and correlated. RESULTS: The condyle and disk both rotated during forward translation within the glenoid fossa during mouth opening. The movement of the disk was smaller than the movement of the condyle, resulting in a posterior rotation of the disk relative to the condyle. The inclination of the condyle path (mean, 61.1 degrees) was significantly smaller than the steepness of the articular eminence (mean, 68.7 degrees). The steepness of the articular eminence was statistically significantly correlated with the degree of disk rotation, which indicated that the disk tended to rotate farther backward in a temporomandibular joint with steeper articular eminence. CONCLUSION: We found that on mouth opening the disk rotated backward relative to the condyle. The posterior disk rotation was more prominent in joints with a steep articular eminence than in joints with a less steep eminence. The results may be helpful for understanding the biomechanics of the temporomandibular joint, especially relative to the development of disk displacement.

Adult↗

PubMed1998

Mandibular height asymmetry following experimentally induced temporomandibular joint disk displacement in rabbits.

OBJECTIVE: The purpose of this study was to test the hypothesis that nonreducing disk displacement of the temporomandibular joint causes mandibular asymmetry. STUDY DESIGN: Unilateral anterior temporomandibular joint disk displacement with intact posterior disk attachment was surgically created in the right joints of seven growing rabbits. In each of seven sham animals, the right temporomandibular joint was surgically opened without any disk manipulation. Seven animals served as references. For identification of ramal growth and inferior growth at the mandibular base, tantalum implants were inserted into the mandibular body. Lateral cephalograms were exposed repeatedly throughout the 3-month investigation period. Kruskal-Wallis one-way analysis of variance was used to compare the groups. RESULTS: Compared with the sham and reference groups, the experimental group exhibited a deviant growth pattern, with inferiorly directed growth along the mandibular base and in the gonial area. The ramal height was significantly shorter on the side with disk displacement. No significant side difference was present in the sham and reference groups. CONCLUSIONS: Disk displacement can cause mandibular asymmetry in growing rabbits, including shortening of the mandibular ramus and excessive inferiorly directed bone growth along the lower border of the mandible.

Analysis of Variance↗

PubMed1998

Sources of radiographic distortion in conventional and computed tomography of the temporal bone.

OBJECTIVES: To identify those bony regions of the glenoid fossa where, due to the inclination, there is an increased risk of radiographic distortion in conventional and computed tomography (CT). METHODS: The inclination of the roof and posterior wall of the glenoid fossa was determined relative to established imaging planes. Measurements were performed on 50 corrected coronal MR and 50 axial CT images and 200 sagittal cryosections of 50 temporomandibular joints (TMJs). The location of regions with unfavourable bone wall inclination was identified using the condyle as a reference. RESULTS: The inclination of parts of the fossa roof exceeded the limit for reliable depiction in corrected sagittal and coronal planes in 40% and 8% of the joints respectively. The inclination of parts of the posterior wall of the fossa exceeded the limit for reliable depiction in corrected sagittal and in true sagittal planes in 100% and 84% of the joints respectively. In 84% of the joints the inclination exceeded the limit for reliable depiction in the axial plane. For both bone walls the regions with unfavourable inclination were in the medial part of the joint. CONCLUSIONS: The angulation of parts of the roof and posterior wall of the glenoid fossa in relation to established imaging planes makes them highly susceptible to distortion. The oblique coronal projection is well suited for depiction of the roof of the fossa and preferable to a sagittal projection. An oblique axial projection is required for the posterior wall.

Adolescent↗