The aim of this study was to evaluate the effect of platelet-rich plasma (PRP) on remodeling of autologous bone grafts used for augmentation of the floor of the maxillary sinus. In five edentulous patients suffering from insufficient retention of their upper denture related to a severely resorbed maxilla, the floor of both maxillary sinus was augmented with an autologous bone graft from the iliac crest. Randomly, PRP was added to the bone graft used to augment the floor of the left or right sinus (split-mouth design). Three months after the reconstruction, bone biopsies were taken with a trephine from the planned implant sites (N=30). Subsequently, three implants were placed in the left and right posterior maxilla. Microradiograms were made of all biopsies (N=30), whereafter the biopsies were processed for light microscopic examination. In addition, clinical parameters were scored. Wound healing was uneventful, clinically no difference was observed between the side treated with PRP or not. Also microradiographical and histomorphological examination of the biopsies revealed no statistical difference between the PRP- and non-PRP side. One implant placed in the PRP side of the graft was lost during the healing phase. Implant-retained overdentures were fabricated 6 months after implantation. All patients functioned well (follow-up 20.2+/-4.3 months). In this study, no beneficial effect of PRP on wound healing and bone remodeling was observed. It is posed that PRP has no additional value in promoting healing of grafted non-critical size defects.

This fMRI study investigated the human somatosensory system, especially the secondary somatosensory cortex (SII), with respect to its potential somatotopic organization. Eight subjects received electrical stimulation on their right second finger, fifth finger and hallux. Within SII, the typical finding for both fingers was a representation site within the contralateral parietal operculum roughly halfway between the lip of the lateral sulcus and its fundus, whereas the representation site of the hallux was found more medially to this position at the fundus of the lateral sulcus, near the posterior pole of the insula. Somatotopy in SII seems to be less fine-grained than in primary somatosensory cortex (SI), as, in contrast to SI, no separate representations of the two fingers in SII were observed. A similar somatotopic representation pattern between fingers and the hallux was also observed within ipsilateral SII, indicating somatotopy of contra- as well as ipsilateral SII using unilateral stimulation. Further areas exhibiting activation were found in the superior and inferior parietal lobule, in the supplementary and cingulate motor area, and in the insula.

This study aimed at evaluating the effect of 1 and 4% titanium tetrafluoride (TiF₄) gels, amine fluoride (AmF) 1 and 0.25% and a fluoride varnish (FP) on the prevention of dental erosion. Two experimental groups served as controls, one with no pretreatment and another one pretreated with a fluoride-free varnish (FP-blanco). Dental erosion was modelled using bovine enamel samples submitted to alternate cycles of acid exposure in citric acid and remineralization in artificial saliva. Calcium loss of all samples involved in the study was quantified by atomic absorption spectroscopy and erosion depths were estimated. Two samples of each experimental group were also analyzed by white light confocal microscopy. The cumulative erosion depth (in µm) after 72 min was: TiF₄ gel 1% 8.29 ± 0.39; TiF₄ gel 4% 8.27 ± 0.55; AmF 1% 8.69 ± 0.66; AmF 0.25% 8.86 ± 0.33; FP 3.43 ± 1.07; FP-blanco 14.86 ± 1.59 and control 9.77 ± 0.49. A statistically significant protective effect (p ≤ 0.001) was found only for the group pretreated with the fluoride varnish. Within the limitations of an in vitro study it may be concluded that topical applications of the fluoride varnish tested have a protective effect on the prevention of dental erosion.

No abstract

Medial-to-lateral somatotopy is a well-established feature of the human primary somatosensory cortex (SI); however, it is unknown whether, similarly to non-human primates, a rostral-to-caudal somatotopic arrangement exists as well. Therefore, in this functional magnetic resonance imaging (fMRI) study on eight healthy human subjects, five circumscribed skin areas sequentially located on the third finger and the palm of the hand were stimulated with innocuous electrical pulses. Within area 3b of contralateral SI, successive cortical representation sites ordered in a rostral-to-caudal fashion were seen in the group analysis and in six individual subjects. The fingertip was located most rostrally, whereas the proximal parts of the finger as well as the distal palm were represented at more caudal locations. Within area 1, the group analysis revealed a similar pattern of discrete representations. However, in contrast to area 3b, the fingertip was located most caudally, whereas the more proximal parts of the finger were found to be represented rostrally within area 1. Thus, the representation pattern of area 1 appeared as a 'mirror image' of that of area 3b. In comparison to the representations of the finger and the distal palm, the proximal palm was found to be represented at a more medial position of the postcentral gyrus.

The prevention of dental erosion with fluoride is still largely unknown territory. It was the aim of this study to determine the erosion-inhibiting effect of topical neutral 1% sodium fluoride (NaF) application and an application of a 4% titanium tetrafluoride (TiF4) solution compared with no treatment. Ten bovine incisors were selected and three enamel samples prepared from each tooth. One sample from each tooth was assigned to one of three experimental groups. The experimental treatments were: no fluoride application (control); 4 min application of neutral 1% NaF gel; and 4 min application of 4% TiF4 solution. All of the specimens were repeatedly exposed to 50 mm citric acid solution containing 0.4 mm CaCl2, and 2.2 mm KH2PO4 at pH 3.0 over four consecutive days. The acid exposure was performed in intervals and the intensity was increased over the days of the experiment. Enamel dissolution was determined by calcium content measurement of the acid solution after exposure, using atomic absorption spectroscopy. A statistically significant erosion-inhibiting effect was found for both NaF and TiF4 treatments compared with the control group from an erosion exposure time of 3 min. The reduction of calcium loss, however, was higher for the TiF4-treated specimens than the NaF-treated. From 16 min of erosion exposure, the erosion-inhibiting effect was significantly stronger in the TiF4 than the NaF group. The relative reduction of calcium loss compared with the control group remained stable for the TiF4 group, whereas for the NaF group the relative reduction decreased with cumulative erosion time. It is concluded that topical TiF4 application provides a potential treatment option in erosion prevention.

Human dentin mineral has been investigated by using micro-Raman spectroscopy. Fluorescence and thermal problems were largely avoided by preparing dentin samples by grinding and ultrasonic agitation in acetone. The Raman spectral features were consistent with those of impure hydroxyapatite containing CO3 and HPO4. While spectral differences between enamel and dentin were clearly observable as changes in the bandwidth of the PO4(3-)V1 band and the intensities of the OH-, CO3(2-) and HPO4(2-) bands, the technique could not detect spectral differences between coronal and root dentin. NaOCl, NaF and APF-gel treatments caused measurable changes in intensities of the bands due to CO3(2-) and HPO4(2-); the results were found to be useful for band assignments. After NaOCl treatment, the Raman bands, presumably due to amide and HPO4(2-), were lost, but the band intensity of the CO3(2-)V1 bands increased by 35-60%. This increase coincided with the appearance of a new broad band (250-300 cm-1). The same treatment on enamel caused no increase in the CO3(2-)V1 band intensity. This NaOCl-induced carbonate could be removed within 20 h in a 1000 ppm NaF solution. These findings indicate that the carbonate ions induced by the NaOCl treatment are presumably in or on the mineral surface. After 3 min of APF-gel treatment on NaOCl-pretreated dentin, the intensities of the hydroxyapatite phosphate bands dropped by approximately 20%, and newly formed CaF2 and HPO4 bands became observable.

Topical fluorides have been proposed for the prevention of erosive dental wear. This study evaluated the in vitro effect of a single professional application of 4% titanium tetrafluoride (TiF₄), 1% amine fluoride (AmF) and 0.1% difluorosilane varnish (FV) in preventing wear due to combined erosion and brushing abrasion. One hundred and eight bovine enamel samples were used. Control groups were not pretreated with any product (C), pretreated with a fluoride-free varnish (FV-bl) or pretreated with fluoride varnish and subsequently submitted to varnish removal (FV-r). Wear was modeled by submitting the fluoride-treated and control groups to 3 cycles of the following regimens: erosion/remineralization (er/remin), abrasion/remineralization (abr/remin) or erosion/abrasion/remineralization (er/abr/remin). Erosion was simulated by immersion of the samples for 10 min in citric acid 50 mM (pH 3). Abrasion was carried out for 1 min (200 strokes, load 150 g) in a wear device. Remineralization (2 h artificial saliva) took place between the cycles. Two-way ANOVA showed that there was a significant interaction (p ≤ 0.001) between the fluoride treatments and the wear regimens. Under er/remin a significant wear protective effect was found for the FV, FV-r and FV-bl groups. Abr/remin resulted in some enamel loss for the TiF₄ and AmF groups, but the amounts lost were not statistically significant (p = 0.185 and p = 1.000, respectively). Under er/abr/remin all products showed a significant protective effect, except for TiF₄. It was concluded that FV and AmF protected bovine enamel against erosion followed by brushing abrasion in vitro.