Epidemiological study on periodontal diseases and some other dental disorders in dogs.

The prevalence of dental disorders in dogs was studied by applying index systems for human with some modifications. A total of 251 mongrel dogs including 143 stray dogs kept in the Animal Protection Offices in Tokyo and Hokkaido and 108 pet dogs visiting veterinary clinicians in Chiba Prefecture and Hokkaido were used. Periodontitis was prevalent among these dogs regardless of their sources and its incidence was increased with age. The lesion was more severe and more frequent in the premolar and molar regions than in the maxillary and mandibular incisor regions. Missing of teeth was observed at a high and increasing incidence with age. The tooth most commonly lost was the first premolar, followed by the other premolars and molars, where severe periodontitis was frequently found. Calculus was seen on many teeth, and aging agravated its prevalence and severity. Dental caries was observed in stray dogs, but neither to a serious degree nor at a significant level. These findings emphasize the necessity of dental hygiene, proper dental care and continuous periodical survey for dogs.

Morphology and chemical composition of dental calculi mainly composed of whitlockite.

The morphology and chemical composition of two subgingival calculus samples, which were composed of magnesium-whitlockite with a Mg/Ca molar ratio of approximately 0.1 as shown by X-ray powder diffraction, were analyzed semiquantitatively using energy-dispersive spectroscopy (EDS) combined with scanning electron microscopy (SEM). The Ca/P molar ratio values for 33 EDS-analyzed materials ranged from 1.24 to 2.03 with an average of 1.49, and the (Mg+Ca)/P molar ratio values ranged from 1.43 to 2.28 with an average of 1.63. The average Mg/Ca molar ratio was 0.10, a value very close to that obtained by X-ray diffraction analysis. The EDS-analyzed materials were grouped morphologically into three types; Type A materials were typical rhombohedral crystals, Type B were crystals of ill-defined form or small crystallite aggregations and Type C materials had a small granular structure or were amorphous. The values of (Mg+Ca)/P molar ratio for Type A ranged from 1.57 to 2.28 and averaged 1.81, those for Type B ranged from 1.43 to 1.56 and averaged 1.48, and those for Type C ranged from 1.46 to 2.06 and averaged 1.62. Type A crystals had higher molar ratios while Type B crystallites had values similar to that of whitlockite. Type C materials covered the ranges of both Type A and Type B. These results show that the materials resembling whitlockite morphologically did not have the (Mg+Ca)/P ratio of whitlockite and vice versa. This suggests that whitlockite crystals may substitute some ions for PO4 as well as Mg for Ca to a larger extent than thought previously, and that care is needed in the identification of these materials.

Adhesion of stainable, calcium-rich deposits on substrata with different surface free energies. An in vivo study in beagle dogs.

Calculus plays an important role in chronic inflammatory periodontal disease and tooth loss. Patients can suffer from calculus formation despite good oral hygiene. The strength of adhesion between calculus and the enamel surface, though not determinant for the formation of calculus itself, determines whether calculus remains on the teeth during eating and toothbrushing. In this study, the amount and the strength of adhesion of calcium-rich deposits formed in vivo on different materials are related to substrate surface free energies (sfe). In 4 beagle dogs, fenestrated crowns were made on the upper fourth premolars. Smooth facings of glass (sfe 120 mJ.m-2), polished bovine enamel (sfe 85 mJ.m-2), polymethylmethacrylate (PMMA sfe 56 mJ.m-2) and polytetafluorethylene (PTFE sfe 20 mJ.m-2) were inserted in the crowns for 1, 3, 7, 14 or 28 days. The amount of deposit was evaluated both gravimetrically and planimetrically using Alizarin Red S for staining. Adhesion of calcium-rich deposits was evaluated planimetrically by studying their removal in a brushing machine. Dry weight increased linearly with time (approximately 0.18 mg.cm-2 per day) and was slightly less on PTFE than on the other materials. After 1 to 3 days, staining already revealed a 100% coverage by calcium-rich deposits. The number of strokes required to reduce the planimetric scores by 63% was extremely small on PTFE and PMMA and related with substrate surface free energies. This study shows that a possible way to reduce calculus formation in vivo is to decrease the surface free energy of the enamel using appropriate surfactants in, e.g., toothpastes.

[Effect of local application of NaF on the content of calcium, phosphorus and fluorine in young dental calculus]. / Wplyw miejscowego stosowania NaF na zawartosc wapnia, fosforu i fluoru w mlodym kamieniu nazebnym.

The purpose of the study was determination of changes in the content of calcium, phosphorus and fluorine in young dental calculus developing in vivo in case of not using a rinsing solution of 1% NaF or after its use. The studied material comprised tartar deposited on a foil fastened to the lower incisor in 6 women aged 23-28 years. They were divided into two groups of 3 women in each, one of the groups had a high tendency for mineralization of tartar, while in the other group this tendency was small. The study was carried out in two stages. In the first, control, stage at the time of foil wearing the women rinsed mouth with a placebo solution, in the experimental stage they used 1% sodium fluoride solution for this purpose. The analysis of the superficial distribution of various elements showed a greater density of impulses in the case of calcium and fluorine, and lower density in the case of phosphorus in the deposits formed in the experimental stage as compared to the control stage. Using X-ray microanalysis a statistically significant rise was found of the concentration of calcium and fluorine, and reduced content of phosphorus in the deposits formed after NaF application. The per cent in weight of fluorine in young supragingival tartar from the control stage was 0.2-3.1, while in the experimental stage it rose to 3.0-27.7. The statistical analysis showed that the rise of fluorine content in tartar in cases with low tendency for mineralization of tartar (group II) was statistically significantly higher than in the group with a high tendency for tartar development (group I). The Ca/F ratio calculated on the basis of the results in the control stage was 1.35 to 2.68. After application of fluoride rinsing solution this value rose to 1.96 to 4.34 in the studied women.

[Study on mercury in dental calculus].

It has been reported that dental calculus contains trace elements of mercury besides lead, cadmium and zinc. The mercury is one of the hazardous metal elements from the environmental point of view. The purpose of this study was to clarify the mechanism of the accumulation of mercury in the dental calculus. The results were as follows: 1. The concentration of mercury was 1.6 ppm in the dental calculus collected from the subjects with no amalgam fillings. 2. The most of the mercury was found in the organic fraction of the dental calculus. 3. In the culture study of Bacterionema matruchotii in vitro, with the increase of Bacterionema matruchotii the uptake of mercury by the bacteria increased. And the maximum uptake of mercury was seen between 7 to 14 days of the culture period. 4. After 7 days of culture, the bacterial cells were destroyed into several fractions and the quantity of the mercury in the respective fractions was assayed. About 90% of mercury was found in the cell wall. From these results, it was suggested that the uptake of mercury by the bacteria was the cause of mercury accumulation in the dental calculus.

[Composition and properties of calculus under specific and job-specific viewpoints]. / Zusammensetzung und Eigenschaften von Zahnstein unter umwelt- und berufsspezifischen Gesichtspunkten.

Resulting from phase-analytical and chemical examinations there are characteristically habitual differences in the consistency of dental calculus. Very obvious are sex (gender) specific and job specific differences concerning the contents of heavy metals like lead, cadmium, copper, and zinc. Characteristics concerning the quantity, consistency and temper of dental calculus as well as the peal-homogeneous value (pH-value) of the saliva are obvious with miners working in salt-mines.

Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi.

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed. Identification of the crystalline components were made based on the combined information of the morphology (SEM) and Ca/P molar ratios of the crystals with the morphology and Ca/P molar ratio of synthetic calcium phosphates (brushite or DCPD; octacalcium phosphate, OCP; Mg-substituted whitlockite, beta-TCMP; CO3-substituted apatite, (CHA); and calcite. SEM showed similarities in morphological features of human and animal dental calculi but differences in the forms of crystals present. Microanalyses and crystal morphology data suggested the presence of CaCO3 (calcite) and CHA in the animal (cat, dog, tiger) and of OCP, beta-TCMP and CHA in human dental calculi. X-ray diffraction and infrared (IR) absorption analyses confirmed these results. This exploratory study demonstrated that by taking into consideration what is known about the crystalline components of human and animal dental calculi, combined SEM and microanalyses can provide qualitative identification.

Electron microprobe and microradiographic studies of carious enamel lesions covered with dental calculus.

From a large number of posterior teeth with arrested natural carious lesions some 0.56 percent were found to have arrested approximal lesions with a superficial layer of calculus. The lesions were examined using quantitative microradiography for mineral content and by electron microprobe analysis for Ca, Na, Cl, Mg and P. The conditions in the plaque, which caused the formation of calculus, might also be expected to cause a remineralization of the lesions. However, the lesions examined were found to have a low mineral content in their body, and moreover, had a lower Na/Ca ratio and a higher Cl/Ca ratio than sound enamel; these are characteristics also found in carious lesions not covered with dental calculus. On the assumption that the lesions developed before any plaque calcification occurred, it is concluded that conditions which favour the calcification of plaque do not favour the remineralization of carious lesions in vivo. As only 0.5% of the carious lesions in extracted teeth were covered with calculus, it must be admitted that consecutive periods of lesion formation followed by calculus formation on the same tooth face are rare.

Purification of a protein component in extracts from supragingival dental calculus.

In the present study supragingival dental calculus of unknown age was collected from the mandibular incisors of three individuals and solubilized by EDTA. The extracts were examined by gel filtration, ionic exchange chromatography and amino acid analysis. A protein component with similar characteristics to the main protein component of the acquired enamel pellicle was a regular constituent of the calculus extracts from the three subjects.