Garrett, JS. Cementum in Periodontal Disease. Perio. Abstr. 23:6, 1975. [Review Article]

Overview

• Cementum previously exposed to the oral cavity interfere with healing after periodontal surgery in terms of new connective tissue attachment.
• Findings by Hart, Black, Hartzell and Skillen suggested that bacteria were able to penetrate in cementum to different extents; by proliferating and releasing toxins, bacteria kept the periodontal membrane inflamed and also made cementum incompatible with the overlying tissues. On the other hand, Stones observed that cementum becomes impermeable from pulp or PDL at adult life. Gottlieb in 1942, concluded that continual cementum deposition was necessary to maintain periodontal health, once periodontal disease is a disease of cementum.

Literature on cementum can be divided in 4 topics

1. Cytotoxic effects of exposed root surfaces: diseased root specimens placed in tissue culture will induce irreversible morphologic changes in the cells of the culture. Also, extracted cementum endotoxins were able to decrease fibroblast growth in tissue culture media. It has not been shown if endotoxins really invade cementum or if they are just present as part of bacterial plaque trapped in areas of cementum decalcification but, endotoxins are inflammatory agents that do not allow eradication of disease.
2. Light microscope descriptions: granules are present within the exposed cemental layer. They are more numerous in calculus deposit areas. It was speculated that they may be the bacterial portion of the calculus attachment. Granules disappear when decalcification processes are applied. Granules appeared in 4 basic morphologic patterns: (1)grape-like structures; (2) long chain aggregates; (3) small isolated vacuoles; and (4) a very long fissure-like area. The vacuoles follow intact collagen fibers orientation and may be where the collagen fibers degenerated.
   Cementum apposition increases throughout life; teeth with periodontal disease have a thinner cementum. Lacunar resorption has been observed to be increased in periodontally diseased teeth, although the mechanism by which it happens has not been elucidated.
3. Transmission electron microscope descriptions, microradiographic descriptions, and chemical analysis: exposed cementum has a decrease or loss of collagen crossbanding at or near the cemental surface and a hypermineralized cemental surface. The possible mechanisms for the collagen decrease or loss are: (1) action of the factors responsible for the breakdown of collagen in surrounding connective tissue before the cementum is exposed (collagenase and proteolytic enzymes) and (2) action of bacteria and salivary enzymes would produce the changes after cementum is exposed.
   Exposed cementum can present areas no change, surface demineralization, and hypermineralization (most common). Hypermineralized cementum has disorganized, disoriented, thicker crystals; this probably happens by further mineralization of the original crystals. Hypermineralization may occur by the presence of higher concentrations of Ca and phosphate of plaque in contact with cementum when compared to their concentration in the saliva. Also, change in the organic matrix (less collagen) can play a role and may be enough to induce changes in the mineralization pattern. Other investigators think that calcium and phosphate concentrations in saliva itself are enough to produce a hypermineralized zone.
   Hypermineralization comes from surrounding fluids and not from adjacent mineral tissues, once no decrease in mineralization was observed in areas under the hypermineralized areas. Hypermineralization can reach 50 µ in depth (half cementum thickness).
   Cementum exposed to the oral environment has higher mineral content (increases in calcium-?, magnesium, fluoride and phosphorus).
4. Scanning electron microscopic descriptions: projections above the normal surface plane and some depressions were demonstrated. At the base of the pocket, spaces between projections were partially filled; cementum exposed longer to the oral surface seemed to be covered by calculus with no holes where Sharpey's fibers used to insert.

Back: Cementum Articles
Menu: Literature Review Topics
Home: PIC Homepage