The non-collagenous dentin matrix proteins are involved in dentinogenesis imperfecta type II (DGI-II)

Dentinogenesis Imperfecta type II (DGI-II) is a localized form of mesodermal dysplasia of the dentin affecting both the primary and permanent dentitions. This is an autosomal-dominant disease in which there is a disorder in dentin mineralization. Several studies have localized DGI-II to human chromosome 4 in the region 4q 12-21. Many ECM genes-such as OPN, DMP1, DMP2, DMP3 (DSPP), and BSP-have been mapped to the same locus. Biochemical studies indicated that dentin phosphophoryn (DMP2) might be a candidate gene in DGI-II. In this study, we have used histological and RFLP analyses of tissues from a DGI-II-affected patient, as compared with two normal controls, to determine if DMP1, 2, or 3 was linked to DGI-II. The histology of the affected tooth was very different in the DGI-II patient as compared with the normals. In particular, the dentinal tubules in the DGI-II patient were very irregular, which could be the result of perturbations in the process of dentin formation. Patient and control DNA samples were digested with EcoRI or PstI and Southern-hybridized with the DMP1, DMP2, and DMP3 cDNAs. Few differences in the restriction pattern were observed between affected and normal samples for DMP1 and DMP3-3' region (phosphophoryn-like sequences) probes. On the other hand, DMP2 showed a dramatic shift in the restriction pattern in DGI-II. This study suggests that the different restriction enzyme digestion profiles of the DNA from the DGI-II patient, as probed by DMP2, might be related to the defective mineralization of dentin in DGI-II.     

In vitro study of the inactivation by dentine of some endodontic medicaments and their bases

Background: The aim of this study was to investigate the antimicrobial effect of endodontic medicaments and their bases in the presence of dentine powder. Methods: The medicaments tested were Ledermix paste, Pulpdent paste, a 50:50 combination of the Pulpdent:Ledermix and their bases. The test organism was Enterococcus faecalis ATCC 29212. The presence or absence of dentine was examined as well as the effect of autoclaving dentine. Serial dilutions of samples at 1 hour, 1 day and 3 days were used for colony counting. The effects of dentine powder on pH for saturated Ca(OH)₂ solution and Pulpdent paste at 1 hour and 24 hours were also measured. Results: Pulpdent and the 50:50 combination of Pulpdent:Ledermix completely inhibited the growth of E. faecalis from 1 hour onwards, and these results were not affected by the presence/absence of dentine powder, pre‐incubation period, timing of autoclaving, or exposure time. Saturated solutions of Ca(OH)₂ are prone to inactivation by dentine powder unlike Pulpdent paste. Ledermix paste took 3 days to exert a significant effect on the growth of E. faecalis. Conclusions: In this laboratory study, both Pulpdent and the 50:50 mixture of Pulpdent with Ledermix were effective medicaments against E. faecalis in the presence of dentine powder.     

A comparative study of sialic acid-rich proteins in rat bone and dentin

Four sialic acid-rich (SA-rich) proteins found in bone and dentin, osteopontin (OPN), bone sialoprotein (BSP), bone acidic glycoprotein-75 (BAG-75), and dentin matrix protein 1 (DMP1), share some common features. We used SDS-PAGE and Western immunoblots to analyze and compare SA-rich proteins in bone and dentin extracts from rats with a single chromatographic procedure. OPN was detected in dentin extracts, with a relative level less than one-seventieth of that in bone. Both bone and dentin BSP demonstrated an extremely broad distribution pattern, probably due to a high degree of heterogeneity in post-translational modifications. BAG-75 in both bone and dentin was detected as an 83 kDa band, dramatically distinct from that of DMPI. Using a polyclonal antibody raised against a purified bone 57 kDa protein (a portion of DMPI), we detected 150 kDa protein bands in bone fraction; the same bands were recognized by antirecombinant rat DMPI antibody. Bands from dentin migrating at about 150 kDa in earlier fractions and progressing to 200 kDa in later fractions showed a clear immunoreactivity to the anti-57 kDa antibody. We conclude that the majority of DMPI in rat bone is processed into fragments, whereas that in dentin remains intact.     

A Rationale For Not Connecting Implants to Natural Teeth

When restoring partially edentulous arches with implants, there are some practitioners who believe it is occasionally beneficial to connect implants to natural teeth. This connection is performed to gain shared support from the natural tooth and implant, prevent rotation of the restoration, or sometimes merely to retain the natural tooth. A discussion and review of the literature concerning this connection is presented, and a patient treatment is shown to illustrate potential complications.     

Factors influencing the cost-effectiveness of community health center dental programs in the U. S. A.

abstract The community health center has been viewed by many Americans as an important mechanism for the improvement of health of the urban poor. The millions of dollars allocated for a relatively small percentage of the population, however, has led to some criticisms of the concept. This paper deals with factors influencing the cost of dental services in a community health center and an analysis of several existing programs. The major factors affecting the cost effectiveness of the clinics appear to be the (1) broken appointment rate, (2) age distribution of the population served, (3) mixture of services rendered, and (4) additional community services rendered. Programs which have low broken appointment rates and which treat both adults and children seem to maintain a higher revenue-cost ratio. This ratio was in the range of 0.78 to 1.10 for the three dental programs studied.