Use of bar-clip attachments to enhance the retention of a maxillofacial prosthetic obturator: a clinical report

Precision attachments are commonly used in prosthetic dentistry but are still questioned in maxillofacial prosthetics. The aesthetic enhancement and functional rigidity provided by attachments are favourable features to many challenging clinical situations such as class-III defect (Aramany's maxillectomy classification). Surgical reconstruction is the standard treatment for this type of defect repair. However, owing to the need for dental rehabilitation and patient reserve, prosthetic rehabilitation was the modality chosen in this clinical case. The use of bar attachments is described in this paper as providing increased stability and retention of the prosthesis, and improved obturator water and airtightness.     

In vitro analysis of 'smear layer' on human dentine using ac-impedance spectroscopy

OBJECTIVE: To analyse smear layers on human dentine using ac-impedance spectroscopy. METHODS: Dentine samples were prepared from extracted, sound, third molars. Impedance measurements were carried out on dentine samples before and after etching. After measuring, samples were examined under scanning electron microscope (SEM) to correlate electrical measurements with structure. RESULTS: Marked differences in impedance before and after etching were demonstrated. SEM investigation showed that a smear layer overlies dentine surfaces before etching, but completely disappeared after etching, leaving open dentinal tubules. CONCLUSIONS: The clinical removal of smear layers is still subjective. This objective method, based on combined ac-impedance and admittance measurement in vitro, has the potential to allow development of standardised techniques and if developed further may be of use in vivo.     

Adjustment of the occlusal vertical dimension in the bite-raised guinea pig

In humans, the inappropriate occlusal vertical dimension (OVD) causes several orofacial disorders, such as bruxism and pain in the masticatory muscles and temporomandibular joint. However, it is still unclear how strictly the OVD is adjusted. To answer this question, we studied the temporal change of the OVD in bite-raised young guinea pigs. The OVD was raised by fixation of a bite-raising appliance to the lower incisors, and increased by either 3 or 1.5 mm at the first molars. After the space produced between the upper and lower molars was filled within 10 days due to eruption of the molars, the appliance was removed. In the bite-raised animals, the raised OVD was reduced until it attained that observed in the control animals, after which the OVD increased according to cranial growth. These results show that the OVD is developmentally changed and strictly controlled.     

Influence of enamel thickness on quantification of mineral loss in enamel using laser-induced fluorescence

The objective of this study was to evaluate the effect of enamel thickness on the quantification of white-spot lesions with laser fluorescence. One hundred and twenty 3-mm-diameter human ground and polished enamel specimens were used. Specimens were illuminated by a 488-nm argon laser, images were acquired through a 540-nm high-pass filter and stored on the Quantitative Light-Induced Fluorescence (QLF) program. Specimens were divided into two groups and demineralized for 48 or 96 h and QLF images were again acquired. Fluorescence radiance (FR) of both sound (FR(s)) and demineralized (FR(d)) enamel was determined using the QLF program. Change in fluorescence radiance (Delta FR, %) was determined as follows: Delta FR = FR(d)/FR(s) x 100. One thin section was obtained for transverse microradiography analysis. Enamel and dentin thickness of the thin sections were measured. There was a good correlation between QLF parameters and enamel thickness. It can be concluded that the FR observed for similar lesions depends on the actual enamel thickness.     

Three-dimensional reconstruction studies and morphometric analysis of rudimental tooth primordia in the upper incisor region of the sheep (Ovis aries,Ruminantia)

The functional dentition of the domestic sheep lacks all upper incisors and the upper canines. Nevertheless, occurrence of a dental lamina and rudimental tooth primordia had been described in the upper incisor region of the sheep. The aim of this study was to describe temporo-spatial pattern of origin and regression of these rudimental tooth primordia by light microscopy, computer-aided three-dimensional reconstruction and morphometry of the dental epithelium. Transient existence of a dental lamina in the upper incisor region of the sheep and three epithelial thickenings on its deep mesenchymal margin has been observed at day of ontogeny (DO) 48-53. They could not been identified as full-value tooth primordia, because they did not induce differentiation of tooth mesenchyme, but they could represent last remnants of functional upper incisors in early ancestors of ruminants. Additionally, a large rudimental upper canine primordium near the sutura maxilloincisiva occurred at DO43, reached early cap stage at DO52 and started to regress at DO53. Thus, our findings showed a discrepancy between the embryonic and adult dental pattern in the sheep. Similar molecular mechanisms as described for diastemal tooth rudiments in rodents could be involved during regression of rudimental tooth primordia in the upper incisor region of the sheep.     

Helicobacter pylori and Campylobacter rectus share a common antigen

AIM: The aim of this study was to investigate the presence of antigens with immunological cross-reactivity in periodontopathogenic bacteria and Helicobacter pylori, the pathogen associated with gastritis and peptic ulcers in human. MATERIALS AND METHODS/RESULTS: Among the putative periodontopathogens tested (Actinobacillus actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola), cross-reactive bands were only detected in C. rectus by SDS-PAGE/Western immunoblotting analysis using a polyclonal antibody directed to H. pylori cells. One of these cross-reactive antigens, a 64-kDa band antigen, also reacted with a monoclonal antibody directed to the human heat shock protein (HSP) 60. The N-terminal amino acid sequence of this C. rectus protein revealed a high degree of homology with corresponding regions of other HSPs belonging to the HSP60 family, indicating that the 64-kDa antigen was a GroEL protein. The nucleotide sequence of the C. rectus GroEL protein coded for a 547 amino acid protein with a predicted size of 57.8 kDa. Comparison of the alignment of the deduced amino acid sequence of the GroEL protein of C. rectus with that of H. pylori showed a high degree of similarity throughout its length (76.8%). GroEL protein from C. rectus possessed the ability to stimulate production of IL-6 by a confluent monolayer of human gingival epithelial cells and was cytotoxic when used at a high concentration. CONCLUSIONS: This study reveals an immunological relationship between H. pylori and C. rectus, and clearly indicates that one of the shared antigens is a GroEL protein possessing a biological activity that might play a role in the initiation and progression of periodontal disease.     

Mineral trioxide aggregate (MTA) and calcium hydroxide as pulp-capping agents in human teeth: a preliminary report

AIM: To compare mineral trioxide aggregate (MTA) with calcium hydroxide when used as pulp-capping materials in human teeth. METHODOLOGY: Eleven pairs of maxillary third molars in subjects between 20 and 25 years of age were subjected to mechanical pulp exposure. The exposed pulps were capped with MTA or calcium hydroxide, covered with ZOE and restored with amalgam. A total of 14 teeth were extracted after periods of 1 week (two molars) 2 months (three molars), 3 months (five molars), 4 months (two molars) and 6 months (two molars). RESULTS: Histological evaluation demonstrated less inflammation, hyperaemia and necrosis plus thicker dentinal bridge and more frequent odontoblastic layer formation with MTA than calcium hydroxide. CONCLUSIONS: Although the results favour the use of MTA, more studies with larger samples and a longer follow up are suggested.     

The effectiveness of bonded composite restorations in the treatment of painful,cracked teeth: six-month clinical evaluation

This study investigated the clinical efficacy of a bonded resin composite restoration with and without cuspal coverage for the treatment of painful, cracked teeth. Patients in a private dental practice who presented with complaints were selected. Inclusion criteria were sensitivity to cold, biting and a clinically-visible crack after removal of the existing restoration. All 40 teeth were restored with a three-step total etch system (Phosphoric acid/Clearfil SA primer/PhotoBond), 20 with cuspal coverage and 20 without. Patients were interviewed at one week, five weeks and six months regarding the presence of pain. In addition, the teeth were clinically examined after six months to reveal any sensitivity. At one week, patients reported that 12 teeth (30%) were free of pain and 28 teeth (70%) still had symptoms. At five weeks, patients reported that 25 teeth (62.5%) were free of pain and 13 teeth (32.5%) still had symptoms. Two teeth (5%) needed endodontic treatment after two and five weeks. At six months, patients reported that 30 teeth (75%) were functioning without any complaints. Upon clinical examination, only 20 teeth (50%) were free of symptoms. No statistically significant difference between the results of the teeth treated with and without cuspal coverage could be shown (Fischer's exact test at p<0.05).     

Eruption of teeth associated with a dentigerous cyst by only marsupialization treatment: a case report

The purpose of this case report was to describe the management of a mandibular dentigerous cyst in a 10-year-old male patient. Without any clinical symptom, the lesion was detected in a routine panoramic radiograph showing a well-defined osteolytic lesion that measured 3 cm in diameter, partially surrounding the crown of the canine, first molar, and second premolar displacing the teeth to the mandible's lower border. The apex of the teeth were still open. Under local anesthesia, the patient was treated by: extraction of the left deciduous canine and first and second deciduous molars; and marsupialization of the cystic cavity. After 30 months, the premolar had erupted and an orthodontic therapy was started to maintain space for the canine.