Properties of axially loaded implant-abutment assemblies using digital holographic interferometry analysis.

OBJECTIVE: The aim of this study was to (i) obtain the force-related interferometric patterns of loaded dental implant-abutment assemblies differing in diameter and brand using digital holographic interferometry (DHI) and (ii) determine the influence of implant diameter on the extent of load-induced implant deformation by quantifying and comparing the obtained interferometric data. METHODS: Experiments included five implant brands (Ankylos, Astra Tech, blueSKY, MIS and Straumann), each represented by a narrow and a wide diameter implant connected to a corresponding abutment. A quasi-Fourier setup with a 25mW helium-neon laser was used for interferometric measurements in the cervical 5mm of the implants. Holograms were recorded in two conditions per measurement: a 10N preloaded and a measuring-force loaded assembly, resulting with an interferogram. This procedure was repeated throughout the whole process of incremental axial loading, from 20N to 120N. Each measurement series was repeated three times for each assembly, with complete dismantling of the implant-loading device in between. Additional software analyses calculated deformation data. Deformations were presented as mean values±standard deviations. Statistical analysis was performed using linear mixed effects modeling in R's lme4 package. RESULTS: Implants exhibited linear deformation patterns. The wide diameter group had lower mean deformation values than the narrow diameter group. The diameter significantly affected the deformation throughout loading sessions. SIGNIFICANCE: This study gained in vitro implant performance data, compared the deformations in implant bodies and numerically stated the biomechanical benefits of wider diameter implants.

Surgical treatment of excessive gingival display using lip repositioning technique and laser gingivectomy as an alternative to orthognathic surgery.

Excessive gingival display (EGD) is a condition in which an overexposure of the maxillary gingiva (>3 mm) is present during smiling. The proper diagnosis and determination of its etiology are essential for the selection of the right treatment modality. Different techniques have been used in cases of hyperactive upper lip: botulinum toxin injections, lip elongations with rhinoplasties, lip muscle detachments, myotomies, and lip repositions. This report presents a case of a young woman with an EGD larger than 10 mm during smiling caused by altered passive eruption, vertical maxillary excess, and a hyperactive upper lip that was treated with a modified lip repositioning technique and laser gingivectomy because she strongly refused orthognathic surgical treatment. A novel addition to the technique is proposed, a reversible trial accomplished just by applying sutures on the borders of the future split-thickness flap, marked using diode laser, before starting the flap incision.

Assessing Health-Related Quality of Life with Antimicrobial Photodynamic Therapy (APDT) and Low Level Laser Therapy (LLLT) after Third Molar Removal.

INTRODUCTION: The purpose of this study was to evaluate the antimicrobial photodynamic therapy (APDT) and low level laser therapy (LLLT) on wound healing, pain intensity, swelling problems, halitosis and the postoperative usage of analgesics after surgical removal of lower third molars. METHODS: One hundred and fifty patients, randomly divided into three groups were selected (50 per each group). The P1 group received the APDT after a third molar surgery, the P2 group received the LLLT and the C group (control group) was without any additional therapy after surgery. A photoactive substance was applied in the APDT study group before suturing. After 60 seconds the photosensitive substance was thoroughly washed with saline water and the laser light was applied in two intervals (30 seconds each). The irradiation power was 50 mW while the wavelength was 660 nm. The laser therapy in P2 group was performed before suturing and the laser light was applied also in two intervals (90 seconds each), the irradiation power was 90 mW while the wavelength was the same as in the first group - 660 nm. Postoperative follow-ups were scheduled on the third and the seventh day in patients who received laser therapy. RESULTS: The results of the postoperative evaluation showed that there was a statistically significant difference in the postoperative wound healing, pain intensity, swelling problems, halitosis and analgesics intake between patients in all three groups (p<0.001). The patients that were subjected to APDT (P1) had the least postoperative problems. After the laser therapy (P1 and P2) wound healing was without any complications, opposite from the patients from the C group (p<0.001). Postoperative application of a laser therapy significantly reduced patient's use of analgesics over the observed period of time (p<0.001). CONCLUSION: Both modalities of laser therapy significantly reduced postoperative problems after surgical removal of third lower molars with the best results in both laser groups.

Comparison of Er:YAG laser and surgical drill for osteotomy in oral surgery: an experimental study.

PURPOSE: High-energy lasers have been proposed as an alternative to the conventional surgical drill in oral and maxillofacial surgery. The aims of this study were to compare thermal changes of the bone surface, procedure time, and volume of the removed bone after drilling with an erbium (Er):yttrium-aluminum-garnet (YAG) laser versus a low-speed surgical drill. The bone sections were observed under light microscopy and examined histologically. MATERIAL AND METHODS: Thirty bone blocks were prepared from porcine ribs. On each block 2 holes (tunnel preparations) were performed using a low-speed, 1.0-mm-wide, surgical pilot drill and an Er:YAG laser (pulse energy, 1,000 mJ; pulse duration, 300 µs; frequency, 20 Hz). The temperature induced by the preparation techniques was measured using an infrared camera. The removed bone volume was calculated by a modified mathematical algorithm. The time required for the preparation was measured with a digital stopwatch and a time-measurement instrument integrated within the computer program. The cortical and spongiose surfaces of the specimens were examined microscopically and histologically under a light microscope with a high-resolution camera. RESULTS: The Er:YAG laser removed significantly more bone tissue than the drill (P < .01) in a significantly shorter time (P < .01). The temperature was statistically lower during the laser preparation (P < .01). Cavities prepared with the laser were regular with clear sharp edges and knifelike cuts. In the drill group, the preparations exhibited irregular edges full of bone fragments and fiberlike debris. Histologic examination of the laser sides showed a 30-µm-thick altered sublayer. The tissue in the drill group was covered with a smear layer without any alterations. CONCLUSIONS: The Er:YAG laser produced preparations with regular and sharp edges, without bone fragments and debris, in a shorter time, and with less generated heat. Thermal alterations in the treated surface were minimal.

Densitometric analysis of dental implant placement between flapless technique and the two-stage technique--a pilot study.

Flapless technique is a surgical approach of implant placement without raising a mucoperiosteal flap. Such approach has many advantages: shorter surgical treatment, minimal bleeding, postoperative discomfort for the patient is reduced; possibility of immediate loading of the inserted implant, faster procedure of implant placement and by that less time is needed for the complete implant-prosthetic restoration. Purpose of this pilot study was radiographic assessment of flapless technique and determination of its clinical values in comparison with two-stage dental implant technique through computerized densitometric analysis. The sample consisted of 10 patients with missing teeth in the premolar region in the upper jaw. An implant was placed in that position. In the first group of 5 patients the implants were inserted with the flapless technique, and in the other group of 5 patients implant insertion was done with a two-stage technique. All inserted implants were loaded with metal-ceramic crowns 3 months after placement. The patients were followed for 18 months through clinical follow-ups and radiovisiographical (RVG) images made after 3, 12 and 18 months. After comparing the average densities, the results showed similar decrease of density in both groups, conventional two-stage technique showed 3.24 and flapless technique 1.23. It can be concluded that flapless technique in everyday clinical usage has the same result as the two-stage dental implant technique.

West syndrome with periventricular leukomalacia: ten-year clinical study.

The aim of the study was to evaluate magnetic resonance imaging (MRI) findings in infants with periventricular leukomalacia (PVL) and West syndrome (WS) and determine the neurodevelopmental outcome in children with West syndrome and PVL. Ultrasound and brain MRI were performed in 37 infants with recognized PVL. PVL was categorized according to De Vries, whereas West syndrome was categorized according to International League Against Epilepsy 1989. West syndrome in our patients developed during the first 2 years of life. The most common interictal abnormality was hypsarrhythmia. All, except two patients had delayed development and various degrees of mental retardation. The most characteristic neuroimaging findings were major reduction in cerebral cortical gray matter volume, reduction in the volume of brain myelin, and delayed myelination. These findings may explain the anatomical association between the West syndrome onset and PVL and intellectual and cognitive deficit in premature infants with PVL.

Glycosphingolipid expression in cerebrospinal fluid of infants with neurological abnormalities: report of three cases.

The aim of this study was to analyse glycosphingolipid expression in cerebrospinal fluid (CSF) from one idiopathic West syndrome (IWS) infant, one with Reye like syndrome, and one with congenital hydrocephalus, in comparison to control group (n=7) using highly sensitive thin-layer chromatography-immunostaining methods. Gangliotetraose-series gangliosides (acidic glycosphingolipids) were not detected in CSF of infant with idiopathic West syndrome and infant with congenital hydrocephalus. CSF of infant with IWS showed traces of neolacto-tetraose ganglioside fractions, which were absent in all other CSF examined. In addition, lactosylceramide fraction, and one ceramide fraction were highly expressed only in IWS CSF These results confirmed previously described lack of gangliotetraose-series gangliosides in IWS patient and for the first time is described increased expression of neolacto-series glycosphingolipids in IWS patient. Since follow up until the age of five years showed almost normal IWS patient psychomotor development, the discribed shift of glycosphingolipid expression may implicate on transient inhibition of specific glycosyl transferases in the age of seven months.