Tomographic analysis of nasomaxillary and zygomaticomaxillary buttress bone thickness for the fixation of miniplates.

The purpose of this study was to evaluate the bone thickness of the nasomaxillary and zygomaticomaxillary buttresses to identify the most favourable region for the installation of miniplates. Bilateral tomographic images of 103 individuals were evaluated, for a total of 206 nasomaxillary and zygomaticomaxillary buttresses. Measurements of bone thickness were performed in the parasagittal reconstructions along three vertical lines on the nasomaxillary buttress (21 measurement points) and four vertical lines on the zygomaticomaxillary buttress (28 measurement points). The vertical line measurements for each buttress were compared using the Kruskal-Wallis test. Spearman's correlation coefficient was used to determine the correlation between the thicknesses obtained and patient sex and side (right/left). The level of significance adopted was 5%. The nasomaxillary and zygomaticomaxillary buttresses presented statistical differences in thickness at their respective points (P=0.001). The analysis of the nasomaxillary buttress showed that the thicker bone for the installation of miniplates follows the long axis of the upper canine at a distance of 3mm from the root apex. For the zygomaticomaxillary buttress, thicker bone to install miniplates was found distal to the distobuccal root of the first molar, at a distance of 3.5mm from the limit of the infraorbital foramen.

Validity of computed tomography in diagnosing midfacial fractures.

The aim of this study was to evaluate the sensitivity, accuracy, and reliability of two-dimensional computed tomography (2D-CT) scans (axial, coronal, sagittal planes) and three-dimensional computed tomography (3D-CT) reconstructions in diagnosing midfacial fractures in relation to actual fractures identified clinically and during surgery (gold standard). The imaging diagnosis was performed by a radiologist and an oral and maxillofacial surgeon. Sixty-two patients with a total of 429 midfacial fractures were included. Frontal sinus and nose fractures were easily diagnosed. For the three CT planes, there was a statistically significant difference between the CT examination and the gold standard for five to seven of the nine bones evaluated, while for 3D-CT, a difference was observed only for fractures of the orbital floor. The inter-observer agreement between the oral and maxillofacial surgeon and the radiologist was 75.5%. In conclusion, in this study 3D-CT reconstructions showed significantly the best sensitivity, accuracy, and reliability for the diagnosis of midfacial fractures. The sagittal reconstructions were the least diagnostic of the 2D-CT images. For areas where the parameters studied showed less agreement and hence a more difficult diagnosis, we recommend a combination of 3D and 2D-CT images to improve diagnostic accuracy.

Fall of amalgam restoration: a 10-year analysis of an Australian university dental clinic.

BACKGROUND: The use of amalgam in Dentistry has decreased since the 1980s. This study aimed to (i) assess the time trend in the usage of amalgam and composite in posterior teeth at Griffith University Dental Clinic from 2010 to 2019; (ii) to test whether this trend varied according to the dental health provider. METHODS: We analysed clinic records from 2010 to 2019. Prais-Winsten analyses were performed, and the average annual percentages change (AAPC) for amalgam and composite was estimated. RESULTS: There were 397,013 procedures, including 80,995 direct posterior restorations. Amalgam use decreased from 12.9% in 2010 to 0.5% in 2019 among students, while composite use increased from 87.1% to 99.5% of posterior restorations. The annual increase of the composite was 1.4% per year for students, while amalgam decreased by 30.2% per year on average. A similar trend was noted among the dentists. CONCLUSIONS: A significant decrease in the use of amalgam was observed over time for both students and professionals. This trend raises questions about curriculum reviews, focusing on the repair, maintenance and safe removal of amalgam while reinforcing the learning on Minimally Invasive Dentistry and composite restorations based on the patient's caries risk.

Is flapless implant surgery a viable option in posterior maxilla? A review.

This article reviews the literature on the outcome of flapless surgery for dental implants in the posterior maxilla. The literature search was carried out in using the keywords: flapless, dental implants and maxilla. A hand search and Medline search were carried out on studies published between 1971 and 2011. The authors included research involving a minimum of 15 dental implants with a follow-up period of 1 year, an outcome measurement of implant survival, but excluded studies involving multiple simultaneous interventions, and studies with missing data. The Cochrane approach for cohort studies and Oxford Centre for Evidence-Based Medicine were applied. Of the 56 published papers selected, 14 papers on the flapless technique showed high overall implant survival rates. The prospective studies yielded 97.01% (95% CI: 90.72-99.0) while retrospective studies or case series illustrated 95.08% (95% CI: 91.0-97.93) survival. The average of intraoperative complications was 6.55% using the flapless procedure. The limited data obtained showed that flapless surgery in posterior maxilla areas could be a viable and predictable treatment method for implant placement. Flapless surgery tends to be more applicable in this area of the mouth. Further long-term clinical controlled studies are needed.

Enamel demineralization and bracket bond strength when etching with acid and /or Er:YAG laser.

BACKGROUND: Enamel etching for brackets is usually done with phosphoric acid. Er:YAG lasers have been recently used for this purpose with conflicting results. The effects of lasers on tooth demineralization and the effects of different combinations of laser treatments and bonding agents were evaluated in this study. METHODS: The enamel contents of fluorine, calcium oxide and phosphorus pentoxide (P(2) O(5)) were analysed using acid etching, laser treatment or both. The tensile bond strength of metallic and ceramic brackets using Transbond XT and Fuji Ortho LC were also tested, using acid etching, laser treatment or a combination of both. RESULTS: All treatments reduced the contents of fluorine, P(2)O(5) and calcium oxide, and acid reduced P(2) O(5) levels more than laser. The bond strength with laser was weaker than with acid, and stronger when combining both. When using laser, the best adhesive was the Fuji Ortho LC. The combination of laser and acid produced the best results when using Transbond XT. CONCLUSIONS: The demineralization promoted by laser was lower than the one produced with acid. Laser treatment produced lower tensile stress strength than acid, but still enough to produce clinically efficient retention. The combination of laser and acid produced the best retention results.

Measurement of nitric oxide in temporomandibular joint saline aspirates.

Temporomandibular joint (TMJ) saline aspirates, obtained from the upper joint space of 17 patients undergoing TMJ arthroscopy under general anaesthesia were assayed for the presence of nitrite, a stable metabolite of nitric oxide by a spectrophotographic method using the Griess reaction. Measurable levels of nitrites were found in the saline aspirates of both symptomatic and asymptomatic joints. There was no statistically significant difference between the two sides. The presence of nitric oxide metabolites in the asymptomatic joints has not been previously reported in the literature. This finding may represent a latent disease process in the symptomless joint.

Ultrasound stimulates nitric oxide and prostaglandin E2 production by human osteoblasts.

We have previously shown that the therapeutic range of ultrasound heals osteoradionecrotic bone and induces bone formation in vitro. It is well established that nitric oxide (NO) and prostaglandins are crucial early mediators in mechanically induced bone formation. The therapeutic range of ultrasound may act in the same way; therefore, we have investigated the effect of the therapeutic range of ultrasound on NO induction and prostaglandin E(2) (PGE(2)) production in vitro. Two ultrasound machines were evaluated, "traditional" (1 MHz, pulsed 1:4, tested at four intensities) and a "long-wave" (45 kHz, continuous, also tested at four intensities) devices. Ultrasound was applied to human mandibular osteoblasts for 5 min, and incubated at 37 degrees C for up to 24 h. The control group (sham insonated) was treated in the same way. NO was determined by measuring the nitrite concentration in the culture media colorimetrically, and PGE(2) was assayed by radioimmunoassay. Ultrasound produced a significant increase in both induced nitrite and PGE(2) production. The NO synthesis appeared to be via inducible NO synthase (iNOS) on the basis of the time course and levels of nitrite obtained, although the inhibition of other NOS isoforms by aminoguanidine cannot be excluded. PGE(2) synthesis appeared to be via COX-2. With the 45 kHz machine, a significant increase in NO was achieved at three intensities, 5, 30, and 50 mW/cm(2). The 1 MHz machine stimulated the synthesis of both NO and PGE(2), but was significant at only one dose (0.1 W/cm(2(SAPA))). There was no difference between the two machines with regard to PGE(2) synthesis. The time-course experiment revealed peak production to be 12-18 h for both NO and PGE(2). The therapeutic range of ultrasound stimulates both NO and PGE(2) synthesis by human osteoblasts, and the 45 kHz machine appeared to be more effective than the traditional short-wave length. These results may reflect the healing effect of ultrasound on fractures and osteoradionecrosis.

Effect of ultrasound on the production of IL-8, basic FGF and VEGF.

Therapeutic angiogenesis is the controlled induction or stimulation of new blood vessel formation to reduce unfavourable tissue effects caused by local hypoxia and to enhance tissue repair. The effects of ultrasound on wound healing, chronic ulcers, fracture healing and osteoradionecrosis may be explained by the enhancement of angiogenesis. The aim of this study was to identify which cytokines and angiogenesis factors are induced by ultrasound in vitro. Two ultrasound machines were evaluated, a "traditional" (1 MHz, pulsed 1:4, tested at four intensities), and a "long wave" machine (45 kHz, continuous, also tested at four intensities). The ultrasound was applied to human mandibular osteoblasts, gingival fibroblasts and peripheral blood mononuclear cells (monocytes). The following cytokines and angiogenesis factors were assayed by ELISA techniques: interleukin-1beta(IL-1beta), IL-6, tumour necrosis factor alpha (TNF-alpha), IL-8, fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF).A slight stimulation of IL-1beta was noted in all cell types. There was no difference in the IL-6 and TNF-alpha levels. The angiogenesis-related cytokines, IL-8 and bFGF, were significantly stimulated in osteoblasts, and VEGF was significantly stimulated in all cell types. Both ultrasound machines produced similar results, and the optimum intensities were 0.1 and 0. 4 W/cm2 (SATA) with 1 MHz ultrasound, and 15 and 30 mW/cm2 (SATA) with 45 kHz ultrasound.The results show that therapeutic ultrasound stimulates the production of angiogenic factors such as IL-8, bFGF and VEGF. This may be one of the mechanisms through which therapeutic ultrasound induces angiogenesis and healing.

In vitro effects of therapeutic ultrasound on cell proliferation, protein synthesis, and cytokine production by human fibroblasts, osteoblasts, and monocytes.

PURPOSE: The aim of this study was to evaluate several in vitro effects of ultrasound that could revert or prevent the hypoxia, hypovascularity, and hypocellularity observed in osteoradionecrosis. MATERIALS AND METHODS: Two different ultrasound machines were evaluated, a "traditional" (1 MHz, pulsed 1:4) and a "long wave" (45 kHz, continuous) machine, tested at various intensities. Ultrasound was applied to human gingival fibroblasts, mandibular osteoblasts, and monocytes. The assays performed were cell proliferation (DNA synthesis), collagen and noncollagenous protein (NCP) synthesis, and cytokine production (ELISA) involving interleukin (IL) 1 beta, IL-6, and IL-8, tumor necrosis factor alpha (TNF alpha), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF). RESULTS: Both ultrasound machines induced increased cell proliferation in fibroblasts and osteoblasts, between 35% and 52%. The collagen and NCP synthesis were also significantly enhanced to levels up to 112%, the best results being with the 45-kHz machine. The ELISA results showed a slight stimulation of IL-1 beta by all cell types; there was no difference in IL-6 and TNF alpha levels. The angiogenesis-related cytokines evaluated were significantly stimulated: IL-8 and bFGF production was enhanced in osteoblasts, and VEGF production was stimulated in all three cell types. Both ultrasound machines produced the same results, with the recommended intensities being 15 and 30 mW/cm2(SA) for the 45-kHz ultrasound, and 0.1 and 0.4 W/cm2(SAPA) for the 1 MHz ultrasound. CONCLUSIONS: Therapeutic ultrasound induces in vitro cell proliferation, collagen/NCP production, bone formation, and angiogenesis. These findings support its use in prospective clinical trials for the prevention and treatment of osteoradionecrosis.

Therapeutic ultrasound for osteoradionecrosis: an in vitro comparison between 1 MHz and 45 kHz machines.

Mandibular osteoradionecrosis is a serious chronic complication which may follow radiotherapy. Therapeutic ultrasound is a highly effective, inexpensive and readily available means of promoting revascularisation and healing. 'Long wave' ultrasound increases penetration depth and, therefore, seems to be more appropriate than traditional high frequency ultrasound. The aim of this study was to compare a new treatment using 45 kHz with the current standard 1 MHz machine. A traditional 1 MHz machine, pulsed 1:4, at intensities of 0.1, 0.4, 0.7 and 1.0 W/cm2(SAPA) was compared with a long wave machine, 45 kHz, at intensities of 5, 15, 30 and 50 mW/cm2(SA). The ultrasound was applied to human gingival fibroblasts and mandibular osteoblasts in vitro. Cell proliferation (DNA synthesis) and collagen and non-collagenous protein synthesis assays were performed, using radiolabelled thymidine and proline, respectively. Controls were sham-insonated and all readings were given as a percentage of controls. Fibroblast proliferation increased by 47% at 0.7 W/cm2 (1 MHz) and by 43% at 50 mW/cm2 (45 kHz), and osteoblast proliferation increased by 52% at 1.0 W/cm2 (1 MHz), and by 35% at 30 mW/cm2 (45 kHz). Fibroblast collagen production increased by 48% at 0.1 W/cm2 (1 MHz), and by 44% at 15 mW/cm2 (45 kHz) and osteoblast collagen production increased by 55% at 0.1 W/cm2 (1 MHz) and by 112% at 30 mW/cm2 (45 kHz). Long wave ultrasound was, therefore, capable of inducing a comparable or even higher enhancement of bone formation compared with traditional ultrasound, which, with its greater penetration, may accelerate the healing effect of ultrasound on osteoradionecrosis. The suggested intensity for 45 kHz ultrasound is 30 mW/cm2.

[Idiopathic facial pain--Part 1: Definition, classification and etiology]. / Dor facial idiopática--Parte 1: Definição, classificação e etiologia.

The present paper introduces a new concept in the physiopathology and treatment of the called 'temporomandibular dysfunction'. This paper was divided into two parts, this first explaining its definition, aetiology and hypothesis of the idiopathic facial pain. The second part, will mention its treatment, prognosis and recommendations. Under this new view, this 'dysfunction' is part of the called Idiopathic Facial Pain. The idiopathic facial pain is didactically subdivided in (1) facial artromialgia, (2) atypical facial pain, (3) atypical odontalgia and (4) oral dysestesia. Occlusal factors are less important in its aetiology, and psychological and biochemical factors are more recognised. Correct diagnosis is essential, and a full history, including psychological and social aspects is very important. The present management is based on a working model developed in this department and in other world centres, and is revolutionising the clinical management of the patients with idiopathic facial pain.

[Idiopathic facial pain. Part 2: Treatment and prognosis]. / Dor facial idiopática. 2a Parte: Tratamento e prognóstico.

The present paper introduces a new concept in the physiopathology and treatment of the called "temporomandibular disfunction". This paper was divided into two parts, the first explained the definition, etiology and hypothesis of the idiopathic facial pain. In this second part, its treatment, prognosis and recommendations are explained. The treatment consists basically in counselling, and, in a second stage, the use of tricylic antidepressants or similar drugs is used. Occlusal devices are some times used, but have been of less value. Arthroscopy can be used in resistant patients, and surgery is usually not indicated. The present management is based on a working model developed in this department and in other world centres, and is revolutionising the clinical management of the patients with idiopathic facial pain.

The stimulation of bone formation in vitro by therapeutic ultrasound.

A controlled study was performed to evaluate the effects of different ultrasound (US) intensities on 5-day-old mouse calvaria bone in tissue culture. A special technique to apply the US was developed, and the following parameters were measured: collagen and noncollagenous protein (NCP) synthesis (bone formation), and temperature change. It was found that ultrasound at 0.1 W/cm2 (SATA), pulsed 1:4, 3 MHz, 5 min, significantly stimulates bone formation (i.e., the synthesis of collagen and NCP) (p < 0.001 and p < 0.01). However, pulsed ultrasound at higher doses (1.0-2.0 W/cm2 (SATA), pulsed 1:4, 3 MHz, 5 min) significantly inhibited the synthesis of both collagen and NCP (p < 0.05). The temperature measurements showed a maximum rise of 1.8 degrees C [at 2.0 W/cm2 (SATA)] and no detected rise at 0.1 W/cm2 (SATA), suggesting that the effects in this study were primarily nonthermal. These results may reflect the healing effect of US on fractures and osteoradionecrosis and reinforces the use of low intensity US regimens [0.1 W/cm2 (SATA)] in clinical practice.

Miniplates in the frontozygomatic region. An anatomic study.

A study of the frontozygomatic region (FZ) to determine an anatomic basis for the use of miniplates in this area was done. Plaster models were obtained from 35 adult skulls and were sectioned at six defined points. Osseous thickness measurements were made perpendicularly to the bone surface. Measurements to determine the risk of penetrating the cranial cavity were also done. The results show that above the FZ suture 5-mm screws should be used. At the two points below the suture, 7-mm screws can be used. The risk of penetrating to the cranial cavity occurs 10 mm above the suture. The diploe thickness at the level of the anterior cranial fossa floor indicates the use of a 7-mm screw at a distance 13.5-18.5 mm from the suture and 5-mm screws above 18.5 mm.