During which period of human prenatal development does the congenital defects occur?

 # During which period of human prenatal development does the congenital defects occur?

A. Period of ovum

B. Period of embryo

C. Period of morula

D. Period of fetus

The correct answer is B. Period of embryo.

Congenital defects can occur during the period of embryo development. This period typically spans from the third to the eighth week after fertilization. It is during this time that the major organs and body systems begin to form, making the embryo particularly susceptible to external factors that can interfere with normal development and result in congenital defects.

What are the three successive prenatal phases in human development?

 # What are the three successive prenatal phases in human development?

A. Period of ovum, embryo, morula

B. Period of embryo, ovum, foetus

C. Period of ovum, embryo, foetus

D. Foetus, embryo, ovum

The correct answer is. C.  Period of ovum, embryo, and foetus.

The three successive prenatal phases in human development are:

Period of Ovum: This phase begins with fertilization, where the sperm penetrates the egg to form a zygote. The zygote then undergoes rapid cell division through mitosis, forming a ball of cells called a blastocyst.

Period of Embryo: During this phase, the blastocyst implants into the uterine wall and undergoes further development. The cells differentiate and specialize, forming the various tissues and organs of the developing embryo. This period generally extends from the third week to the eighth week of pregnancy.

Period of Fetus: This phase starts after the eighth week of pregnancy and continues until birth. The developing organism is now called a fetus. During this period, the organs continue to mature, and the fetus grows in size and complexity until it is ready for delivery.

Who was the first surgeon to devise an obturator for the treatment of cleft palate?

 # Who was the first surgeon to devise an obturator for the treatment of cleft palate?

A. Paul Aegina 

B. Ambrose Pare

C. John Hunter 

D. Norman Kingsley

The correct answer is B. Ambrose Pare. 

Ambrose Pare, a French surgeon in the 16th century, is credited with devising the first obturator for the treatment of cleft palate. An obturator is a prosthetic device used to close the gap in the roof of the mouth caused by a cleft palate, enabling improved speech and feeding for individuals with this condition. Ambrose Pare made significant contributions to the field of surgery and is considered one of the pioneers in the treatment of cleft palate.

Who was against the extraction of teeth for the achievement of stable results?

 # Who was against the extraction of teeth for the achievement of stable results?

A. Martin Dewey 

B. Edward H. Angle

C. Calvin Case 

D. Lawrence Andrews

The correct answer is B. Edward H. Angle.

Edward H. Angle, often considered the father of modern orthodontics, was known for his strong opposition to the extraction of teeth for orthodontic treatment. He believed in the concept of "normal occlusion" and advocated non-extraction treatment approaches. Angle believed that proper alignment and positioning of the teeth could be achieved without tooth extraction, even in cases of crowding or irregularity.