Histology, dental

Mjor, I. A. (1977). Histological demonstration of bacteria subjacent to dental restorations. Scandinavian Journal of Dental Research, 85, 169-74. 

A. Thylstrup, O. Fejerskov, Clinical appearance of dental fluorosis in permanent teeth in relation to histologic changes, Commun. Dent. Oral Epidemiol. 6 (1978) 315-328. 

O. Fejerskov, A. Thylstrup, M.J. Larsen, Clinical and structural features and possible pathogenic mechanisms of dental fluorosis, Scand. J. Dent. Res. 85 (1977) 510-534. [47] T. Ishii, G. Suckling, The severity of dental fluorosis in children exposed to water with a high fluoride content for various periods of time, J. Dent. Res. 70 (1991) 952-956. B.K.B. Berkovitz, G.R. Holland, B.J. Moxham, Oral Anatomy, Histology and Embryology, 3rd edition, Mosby, Edinburgh, 2002. 

Early dental caries (incipient lesions) are non-cavitated and limited to the outer enamel surface. Clinically, these lesions are identified as visible white spots when the tooth is air-dried (Fig. 11.1). The incipient lesion is known as a subsurface lesion since the surface appears intact. However, histological investigations have shown that below the surface, there are zones that vary in porosity (voids from mineral loss) as well as biochemical composition (e.g. fluoride, water and carbonate content) [29]. The enamel caries can vary from a depth of 100-250 J.m (for incipient caries) to entirely through the enamel ( 1.5mm deep), at which point the cavitated lesion has extended into the underlying dentin [35]. The diagnostic challenge remains early caries detection and the focus has been on caries lesions that form on the tooth crown affecting the enamel. The remainder of the discussion will therefore concentrate on enamel caries. 

This rare disorder is one of the few conditions in which the diagnosis is made on the basis of low serum alkaline phosphatase activities (R6). It is characterized by radiological and histological features resembling rickets (F18, R6), but differs from the other varieties of rickets by the presence of craniostenosis, dental abnormalities (P16), and the excretion in the urine of abnormal quantities of phosphoethanolamine (F20) and inorganic pyrophosphate (R33). Alkaline phosphatase activities are low in a number of tissues, including the skeleton (Mc3), while the circulating enzyme has the characteristics of intestinal alkaline phosphatase (WIO). 

Deporter DA, Watson PA, Pilliar RM, Melcher AH, Winslow TP, Howley TP, Hansel P, Maniatopoulos C, Rodriguez A, Abdulla D, Parisien K and Smith DC (1986a) A histological assessment of the initial healing response adjacent to porous-surfaced, titanium alloy dental implants in dogs. J Dent Res 65 1064-1070. 

Cook, S.D., Kay, J.F., Thomas, K.A. et al. 1987. Interface mechanics and histology of titanium and hydroxylapatite coated titanium for dental implant applications. Int. J. Oral Maxillofac. Implants 2 15. 

Glass blowing, which uses iron pipes, often results in oral changes. Periodontitis, dental abrasion and leukoplakia, which histologically shows parakeratosis, occur most frequently (El-Hadary et al. 1972). Contact allergy has been reported from cyclohexyl thiophthal-imide used as a rubber vulcanizer in a glassblower s pipe (Kanerva et al. 1996). 

The use of fixation screws made from PL in the repair of rabbit proximal femoral osteotomies has been reported. Histologically, at the maximum 48 week follow-up time, healing was obser ed without inflammation. The implants appeared to be completely surrounded by a layer of new bone. This report also references three studies performed by other investigators wherein the incidence of localized osteitis following dental extractions was reduced by 12.7% through the use of a PL surgical dressing (Mty ola a/., 1991). 

The success rate of dental implants increased dramatically during the 1980s [9]. Improved materials, selection of appropriate materials, and advanced technology have resulted in an improved implant/bone interface attachment that is responsible for the increased success. Success of dental implants is measured by the absence of mobility, no ra-diolucency between the bone and implant, and no other adverse symptoms or problems. The most successful dental implant today is the endosseous implant where the implant is anchored into the bone and osseointegrated. Success rates can be as high as 95 % over a five-year period Titanium and Ti-6Al-4V are the most widely used materials for the implants. The effects of surface treatment on the surface oxides of titanium have been shown [72,73]. Titanium was the material of choice for Branemark, who correlated the dental implant surface preparation and purity with the histology results of the interfacial bone [74]. 

In two cases exposure to titanium in dental implants caused reactive lesions in the peri-implant mucosa, diagnosed as epulis, in which metal-like particles were observed histologically [87" ]. One involved a pyogenic granuloma and the other a peripheral giant cell granuloma. 

The two final sections are specifically concerned with aspects of Oral Biology. Section 7 on the Calcified Tissues, which includes chapters on calcium and phosphorus metabolism, biological apatite, mineralized tissues and the mineralization process, helps to bridge the gap between chemistry and dental histology. Finally in Section 8, Biology of the Mouth, consideration is given to biochemical aspects of saliva, the oral flora and the formation and properties of dental plaque. A chapter on plaque diseases completes this survey of dental biochemistry. 

Fig. 12. Histological image of an ion implanted dental implant (xl2). Reproduced with permission from Lifenova Biomedical.

Chehroudi, B., Ratkay, R, and Brunette, D.M. 1992. The role of implant surface geometry on mineralization in vivo and in vitro a transmission and scanning electron microscopic study. Cells Mater. 2 89-104. Cook, S.D., Kay, J.F., Thomas, K.A. et al. 1987. Interface mechanics and histology of titanium and hydroxylapatite coated titanium for dental implant appHcations. Int. J. Oral Maxillofac. Implants 2 ... 

---