Biomedical subjects
A Petersson
Publications and source records attributed to A Petersson.
A case of dentinal dysplasia and-or calcification of the dentinal papilla.
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Socio-odontologic investigation of school children with high and low caries frequency.
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Radiation dosimetry in tomography of the teeth and jaws using a multi-film cassette.
The absorbed doses and energy imparted in lateral and antero-posterior tomography of the teeth and jaws were measured. A multi-film cassette with 5 films was exposed using a diameter of the circular collimator of 1.5 cm. With one exception, the absorbed doses were below 1 mGy. The parotid gland towards the roentgen tube received about 2 mGy in lateral tomography of the mandibular third molar. The energy imparted in lateral tomography was 0.6 mJ and in antero-posterior tomography about 2.5 mJ. Since the radiation doses in tomography of the teeth and jaws were low compared with estimated risk levels, they should not deter from using tomography.
Precision of CNC-milled titanium frameworks for implant treatment in the edentulous jaw.
PURPOSE: The purpose of this report was to describe a new technique to fabricate one-piece, implant-supported titanium frameworks by means of a computer numeric-controlled (CNC) milling technique, and to compare the fit of these frameworks with conventional cast prostheses. MATERIALS AND METHODS: The study comprised 20 patients who were provided with 5 standard Brånemark implants each in the edentulous mandible. The fit of the first 10 prostheses with CNC-milled frameworks was measured by means of a 3-dimensional photogrammetric technique. The distortion of the center point of the framework cylinders was measured in relation to the master cast replicas. These measurements were compared with 10 randomly selected routine prostheses with cast frameworks. RESULTS: No significant differences were found between the 2 groups. The 3-dimensional distortion of the cylinders in the completed prostheses ranged from 3 to 80 microns; no passive framework was observed. More distortion was observed in the horizontal plane (x and y axes) as compared to the distortion in the vertical direction (z axis). CONCLUSION: The precision of fit of the first CNC-milled prostheses presented a comparable fit to the conventional cast frameworks. Consequently, this new technique could be a valid option for the routine fabrication of frameworks for implant prostheses.
Photogrammetry--an alternative to conventional impressions in implant dentistry? A clinical pilot study.
PURPOSE: The purpose of this clinical pilot study was to describe a photogrammetric technique to determine implant positions in the oral cavity, and to test and compare this technique to conventional impression/master cast procedures for fabrication of titanium frameworks with a computer numeric-controlled (CNC) milling technique. MATERIALS AND METHODS: Implant positions were recorded by means of conventional impressions/master casts as well as intraoral 3-dimensional photogrammetric measurements in 2 patients who were provided with 5 Brånemark implants each in the edentulous mandible. For each patient 2 titanium frameworks were made by means of a CNC milling technique (All-in-One). Both frameworks had an identical design, but the orientations of the framework cylinder fit surfaces were machined either from measurements from the master casts or from the intraoral photogrammetric measurements. The frameworks were tried for fit in the oral cavity and on the master casts. RESULTS: Both cases showed different precision of fit when comparing the 2 frameworks on the master casts. One of the 2 photogrammetric frameworks was not considered acceptable when tried on the models. In the oral cavity, however, all 4 frameworks presented comparable fit, and all were accepted for clinical use. CONCLUSION: The clinical experiences with try-in of the 4 different frameworks indicated that the photogrammetric technique could be a valid option for conventional impressions when using CNC milling fabrication in implant dentistry. The different results from the model and oral examinations also imply the difficulties of assessing clinical fit when testing fit at the master cast level only.
Progress in radiologic examination of the temporomandibular joint.
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Occlusal appliance therapy in a short-term perspective in patients with temporomandibular disorders correlated to condyle position.
PURPOSE: The purposes of this study were to compare changes in the condyle-fossa relationship in patients with temporomandibular disorders of arthrogenous origin treated with either a stabilization or a control appliance in a double-blind controlled study, and to compare the changes in the condyle-fossa relationship with the short-term treatment effect in the two treatment groups. The radiographic appearance of the temporomandibular joint was also studied. MATERIALS AND METHODS: Fifty-eight patients with temporomandibular disorders of arthrogenous origin were assigned to two equally sized groups: a treatment group given a stabilization appliance; and a control group, given a control appliance. The study covered 10 weeks. The treatment outcome regarding changes in severity of temporomandibular joint pain on a verbal scale was compared to changes in the condyle-fossa relationship in horizontally corrected oblique lateral transcranial radiographs taken with and without the appliance. Condyle-fossa relationship and structural bone changes were observed before treatment in corrected lateral tomograms. RESULTS: The group treated with a stabilization appliance showed a changed condylar position significantly more often (P = 0.004) than the control group. Of the patients reporting a successful treatment outcome, significantly more (P = 0.006) showed a changed condyle position in the group treated with a stabilization appliance than in the group treated with a control appliance. CONCLUSION: In patients with temporomandibular disorders of arthrogenous origin, the short-term occlusal appliance therapy resulting in a changed condylar position gave relief of symptoms more often than if the condylar position was unchanged.