3D assessment of damaged bicycle helmets and corresponding craniomaxillo-mandibular skull injuries: A feasibility study.

OBJECTIVES: In the Netherlands, cyclists continue to outnumber other road users in injuries and deaths. The wearing of bicycle helmets is not mandatory in the Netherlands even though research has shown that wearing bicycle helmets can reduce head and brain injuries by up to 88%. Therefore, the aim of this study was to assess the feasibility of using 3D technology to evaluate bicycle-related head injuries and helmet protection. METHODS: Three patients who had been involved in a bicycle accident while wearing a helmet were subjected to multi-detector row computed tomography (MDCT) imaging after trauma. The helmets were separately scanned using the same MDCT scanner with tube voltages ranging from 80kVp to 140kVp and tube currents ranging from 10mAs to 300mAs in order to determine the best image acquisition parameters for helmets. The acquired helmet images were converted into virtual 3D surface hence Standard Tessellation Language (STL) models and merged with MDCT-derived STL models of the patients' skulls. Finally, all skull fractures and corresponding helmet damage were visualized and related. RESULTS: Imaging bicycle helmets on an MDCT scanner proved to be feasible using a tube voltage of 120kVp and a tube current of 120mAs. Merging the resulting STL models of the patients' skull and helmet allowed the overall damage sustained by both skull and helmet to be related. CONCLUSION: Our proposed 3D method of assessing bicycle helmet damage and corresponding head injuries could offer valuable information for the development and design of safer bicycle helmets.

Dental treatment need and dental general anesthetics among preschool-age children with cleft lip and palate in northern Finland.

Cleft lip and palate incidence is high in northern Finland. This study aimed to investigate the proportion of children in need of restorative dental treatment among cleft lip and palate patients in northern Finland, as well as their need for dental treatment under general anesthesia. The records of 183 cleft lip and palate patients, treated in Oulu University Hospital from 1997 to 2013, were reviewed. Data on dental caries were analyzed in association with cleft type, considering also the presence of syndromes. The frequency of dental general anesthetic (DGA) use, and of treatments, were also analyzed. Dental treatment need was most frequently observed, in this rather limited study population, in patients with the most severe deformities, namely bilateral cleft lip and palate, of whom 60% had caries. Among the study population, 11.5% (n = 21) had a syndrome. Of those, 57.1% had dental caries at the age of 3 or 6 yr, and only four could be treated without a DGA. Dental treatment under general anesthesia was performed in 14.8% of cleft patients without a syndrome, but in 38.1% of those with a syndrome. General anaesthesia is required for the provision of dental care more often in cleft (17.5%) than in non-cleft (0.2%) patients, and especially for those with a syndrome.

Microcomputed tomography-based assessment of retrieved dental implants.

PURPOSE: The aim of this study was to demonstrate the potential of microcomputed tomography (micro-CT) technology in the assessment of retrieved dental implants. Cases are presented to illustrate the value of micro-CT imaging techniques in determining possible mechanical causes for dental implant failures. MATERIALS AND METHODS: Eight retrieved dental implants were randomly selected from a pool and imaged using a micro-CT device. Source voltages (80 to 100 kV) and source-to-detector distances (65 to 70 mm) were based on signal quality requirements with an additional criterion of achieving the highest resolution with the sample entirely in the field of view in the projection plane. One additional sample was chosen for histology and tomographic imaging so that the information contained therein could be compared. RESULTS: The micro-CT images displayed high contrast between the implant, bone, and background, with negligible metal artifacts. The micro-CT technology used in this study delivered excellent images of the retrieved implants. As a result of the quality and resolution (pixel size: 5.52 to 6.15 µm) of the images, surface morphology as well as internal structures of the retrieved implants could be observed in great detail. The majority of the retrieved implants had increased wear, dents, pits, regular shallow scratches, and deep scratches in the implant-to-abutment engagement area. Furthermore, plastic deformations, microcracks, and brittle implant fractures were observed in two implants. CONCLUSION: The mechanical competence of dental implant components plays a major role in the success of implant treatment. When failures do occur, a nondestructive three-dimensional assessment of such failed implants and their components is helpful in understanding the underlying factors. Micro-CT was found to be a useful tool for the morphologic assessment of retrieved dental implants.

Assessment of removed dental implants in Finland from 1994 to 2012.

PURPOSE: The National Institute for Health and Welfare in Finland (THL) has maintained the Finnish Dental Implant Register since April 1994. The aim of this study was to use the Dental Implant Register to assess the influence of patient characteristics and background factors on dental implant removals in Finland from 1994 to 2012. MATERIALS AND METHODS: THL granted permission to access the Finnish Dental lmplant Register (1994 to 2012) and assess the following factors: total implant placements, total implant removals, time from implant placement to removal, implant types, implant lengths, placed and failed implants by jaw and tooth type, and patient sex and age. RESULTS: A total of 198,538 dental implants (51 different types) were placed between 1994 and 2012. A total of 3,318 (1.7%) of the placed implants were removed during the observation period. A total of 1,856 (1.8%) of the placed implants were removed from the maxilla and 1,462 (1.5%) from the mandible (P < .001). A slight difference in the sex distribution concerning implant failures (3.1% in men vs 2.3% in women) was observed. The median removal time was 247 days postoperatively (range 0 to 11,383 days), and one-third of the implants were removed within the first 142 days. Most of the placed implants were 10 mm or longer (93.3%) with 12 mm being the most commonly used length (23.9%). Shorter implants (8 mm or less) were removed more often (2.5% removal rate) than 9 mm or longer implants (1.5% removal rate). The IMZ Implant system demonstrated the highest overall removal rates (8.5%), while Brånemark Nobel Direct (0.6%) demonstrated the lowest removal rates. Of the most commonly placed implant types (together comprising 60.9% of all implants placed), the Straumann (1.2%) and the Astra Implant (1.2%) systems demonstrated equally low removal rates. CONCLUSIONS: The overall dental implant removal rates in Finland are low. Only slight differences in gender and implant position were observed.

Magnetic resonance imaging assessment of airway status after orthognathic surgery.

OBJECTIVE: The purpose of this study was to determine whether orthognathic surgical procedures create significant objective postoperative airway compromise or edema. STUDY DESIGN: A pilot magnetic resonance imaging (MRI) study was performed on 10 patients undergoing orthognathic surgical procedure to determine the time of maximum postoperative swelling, optimum time for scanning, and the anatomical sites of maximum swelling. Anatomical landmarks within the upper airway were determined. A prospective clinical study was then designed to assess the amount of postoperative airway edema in 40 patients undergoing orthognathic surgical procedure at the Toronto General Hospital. All patients received standard anesthetic and postoperative care. Magnetic resonance imaging scan of the upper airway from the hard palate to the subglottis was performed to assess the cross-sectional areas and volumes 24 to 48 hours postoperatively. The anteroposterior and transverse dimensions of the airway were measured at 3 anatomical points: the hyoid bone, the arytenoid cartilages, and the cricoid cartilage. One staff neuroradiologist assessed all MRI scans. RESULTS: The study group consisted of 24 female and 16 male patients, with a range of 15 to 36 years of age, and a mean of 23 years of age. A total of 56 Le Fort I osteotomies (25 advancements, 27 impactions, and 4 extrusions) and 30 bilateral sagittal split osteotomies (13 advancements, 17 setbacks) were included. Seven patients received single-jaw surgical procedures, 16 patients received double-jaw surgical procedures, and 17 patients received double-jaw as well as chin osteotomies. There was no clinical or radiological evidence of postoperative airway edema in any of the 40 patients irrespective of the type or number of osteotomies performed. CONCLUSIONS: Orthognathic surgical procedure involving osteotomies of the maxilla, mandible, and/or chin did not cause significant airway compromise or edema in the 40 patients studied. Once patients undergoing orthognathic surgical procedure fulfill postoperative extubation criteria, they can be safely extubated.

The osteoinductive activity of bone morphogenetic protein (BMP) purified by repeated extracts of bovine bone.

Native bone morphogenetic proteins (BMPs) extracted from bone have been used clinically to stimulate bone regeneration and repair. However, preparation of purified BMP is a laborious process. This study investigated the yield, activity and cost effectiveness of repeatedly extracting the same bone matrix to produce purified BMP. While repeated extraction was able to increase the yield 62% the activity of the partially purified BMP in later extracts decreased both in vitro and in vivo. This decline in activity appears to be due to an increase in non-BMP contaminants, such as collagen, in the extracts. When the first three extracts were combined and processed together activity was equivalent to that of the first extract. A simple analysis based on the cost of reagents used and the time required for purification indicates that separate processing of the extracts is inefficient while combining the first and second extracts and processing them together would result in a small cost saving. Based on this study we would recommend that the demineralized bone matrix be extracted no more than twice and that the extracts be combined for further processing.