**3.2 Theobromine and oral application**

Theobromine and caffeine contents of the average commercial sweet chocolates are approximately 8:1 ratio [28]. The half-life of theobromine and caffeine is different and that of theobromine is longer than caffeine.

**Figure 7.**

*The chemical formula of three xanthines.*

#### **Figure 8.**

*(Left) Theobromine group: 200 mg/L, Crystal size: 2* μ*m. (Right) Control group: Crystal size: 0.5* μ*m.*

*The Contrasting Effects between Caffeine and Theobromine on Crystallization… DOI: http://dx.doi.org/10.5772/intechopen.101116*

The inhibitory effect of cocoa which contains theobromine on plaque accumulation and cariostatic activity has been suggested [29]. However, its anticaries activity is not strong enough to suppress significantly cariogenic activity [30]. On the other hand, the addition of a water-soluble extract of cacao powder significantly reduced caries scores in specific pathogen-free rats infected with *Streptococcus sobrinus* 6715 [31]. Theobromine-based dentifrice had the added benefits of increasing the salivary pH and decreasing the *S. mutans* levels [32].

### **4. In vivo study exposed theobromine**

#### **4.1 In vivo crystallization studies**

The amount of theobromine added to the maternal diet in the study was 1 mg/100 g body weight. If this amount is converted by the metabolic body weight (kg0.75) [25], this corresponds approximately to slightly more than one to three bars of 1 oz milk chocolate for a 65 kg human. After raising the offspring fed with a maternal diet containing theobromine, molars were extracted and studied the following aspects.

#### *4.1.1 X-ray diffractometry*

A consistent relationship of higher crystallinity, i.e., larger crystallites, in the whole molars from the rats exposed to theobromine, compared to the control and/or caffeine group was observed in the X-ray diffractometry [27].

#### *4.1.2 Microprobe analysis*

Calcium and phosphorus concentrations were determined in the enamel of molars extracted from theobromine exposed rats or control rats by an "ARL-SEMQ"™ electron

#### **Figure 9.**

*Calcium (upper left), phosphorus (upper right) and magnesium (bottom) theobromine group were significantly*  ∗ *(P < 0.05) less than the control.*

microprobe analysis. The instrument was operated at an acceleration potential of 15 kV and a beam current of 1.0 × 10−7 A. Fluorapatite from Cerro de Mercado, Mexico, was used as a standard. The results obtained are shown in our previous report [26, 27].

This study was conducted to see whether the composition of crystallites of the enamel formed by theobromine is different from the control group. The overall content of CaO and P2O5 appears to be comparable within the expected margin of error. This suggests that the composition of crystallites of the enamel between control and experimental groups are the same.

#### **4.2 Dissolution studies**

The same experimental procedures, as was in the caffeine study [16], were conducted. The molars from the offspring whose dams were fed with the diet supplemented with theobromine were extracted. The dissolution studies were done. The result showed decreased dissolution (Ca, P, and Mg) of the ions from this group due to the larger crystal size (**Figure 9**) [27].
