**Figure 2.** Relationship between teeth shade and age groups. A2 was the most frequent shade in all age groups.


**Table 3.** Relationship between teeth shade and age groups showed a statistical significance.

\* *p* < 0.05.


**Table 4.** Pearson Chi-Square test shows the significant level between shade and age groups.

<sup>a</sup> 68 cells (85.0%) have expected count less than 5. The minimum expected count is 0.07.

**Table 5.** Relationship between shade and skin types. Skin color type IV appeared to be the most dominant type.


\* *p* < 0.05.

Shade A1 was related to type I skin color in 57.1% of individuals. Skin color type II had A2 as a dominant shade by 34.1%. A2 and A3 shades were equally observed in skin color type III by 20.3%. A3 shade was observed in 26.9% with skin color IV, while A1 and A2 shared the most observed shade in skin color V by 17.6% (Table 5). The relationship between tooth shade and skin color is exhibited in (Figure 3). The results showed statistically significant differences between shade and skin color groups (*p* < 0.05) (Table 6).

**Figure 3.** Relationship between teeth shade and skin color. Skin color type II had A2 as a dominant shade type.

**Table 6.** Pearson Chi-Square test shows the significant level between shade and skin type.


<sup>a</sup> 81 cells (84.4%) have expected count less than 5. The minimum expected count is 0.01.

#### **4. Discussion**

Selecting a proper tooth shade is considered a complex process during prosthetic rehabilitation, which requires fundamental knowledge of color and esthetic. The dentist's skills in determining the right shade play a role in the success of treatment and patient satisfaction. Multiple factors such as light and background affect tooth color [21]. Some studies prefer using conventional shade tabs, while others consider digital devices for more accuracy and precision [22,23]. Digital devices can detect more data about tooth shade, such as lightness, Chroma, and Hue, which can aid in mimicking the color of adjacent natural teeth.

According to the present study, there was a relation between shade, gender, and skin type. The participants of this cross-sectional study belong to a specific ethnic group (Middle eastern) in a specific country (Saudi Arabia). Considering the regional limitation of the

data collection and sample size, the most dominant tooth shade observed was shape A2. Labban et al. studied the Saudi population's perception of their preference for the desired tooth shade. In the above-mentioned study, the researchers provided the participants with a questionnaire consisting of images that had been modified digitally to illustrate different skin and tooth shade combinations. It was found that people with lighter skin preferred to have lighter teeth shade [9]. On the contrary, data on the participants' skin type and tooth shade were obtained directly without involving participants' subjectivity in the data acquisition. Skin color might be valuable when selecting teeth shade for edentulous patients. In this study, an observation of shade relation to skin color groups was statistically significant. People with type I skin tones possess lighter tooth shade (A1 type). Furthermore, darker skin tones such as type IV and V possess darker tooth shade (A3, A3.5 types). This finding contradicts the previous work of Jahangiri et al. and Al-Nsour et al., who reported that individuals with dark skin color have lighter teeth in comparison to individuals with light skin color [6,12]. This might contribute to different ethnic populations and regional limitations.

The hypothesis that males tend to have darker shades than females was reported in previous studies. Gómez-Polo et al. study showed that 25.4% of females had A2 shade while 18% of males had B3 Shade [9]. Kim et al. reported that females' teeth are lighter and less chromatic than males' teeth [15]. In the current study, females tend to have a lighter shade and less Chroma than males, which was in agreement with previous studies.

Based on our study, aging affects tooth color. Older participants tend to have darker teeth than younger individuals. Haralur observed that teeth become darker with age due to multiple factors such as enamel thickness reduction due to wear and secondary dentin deposition [16]. Furthermore, Karaman et al. reported that a statistically significant difference between age groups was valid for central and lateral incisors [24].

### **5. Conclusions**

Within the limitations of this study, it can be assumed that females tend to have a lighter teeth shade than males. Younger individuals have lighter teeth shades than older people in the Saudi population. The process of shade selection should reflect on the relation between skin color and teeth shade. In terms of skin type, type IV was the most common among the Saudi population. Moreover, people with type I skin tones possess lighter teeth.

**Author Contributions:** Conceptualization and manuscript write-up, H.A. and R.A.; Formal analysis, A.A.; Investigation, N.A.; Methodology, M.A., F.A. and A.B.O. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was conducted in accordance approved by the Institutional Review Board at King Saud University (Ref. No. 21/0010/IRB on 4 January 2021).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data that support the findings of this study are available from the corresponding author upon reasonable request.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

