This maybe because a posterior placing of the condylar head with regard to the skull or to a steep mandibular angle resulting in an evident jaw retrusion. The acquired type of micrognathia occurs after birth and usually is an effect of a disturbance to temporomandibular joint. Growth of mandible depends on the normally developing condyles and the muscle function For example, trauma or infection that affect mastoid, middle ear or the joint will result in ankylosis of temporomandibular joint leading to mandibular micrognathia. MacronagthiaMacronagthia is a condition of abnormally large jaws. The jaw size is usually proportion to the increase in skeleton size. It is usually due to excessive growth of the mandible and can have features including reverse maxillary to mandibular relationship, reverse overjet or absence of overbite. It can also be clinically presented when the glenoid fossa and condylar head is more anteriorly placed, causing mandibular prognathism. Macronagthism can be associated with other medical conditions :-
1. Pagets disease where there is overgrowth of the maxilla, cranium and mandible2. Acromegaly, an endocrine disease, can present with enlargement of bones with growth potential such as the mandible, thickened soft tissues and facial features and spade-like hands 
Macrogenia or MicrogeniaMacrogenia and microgenia occur when there is a normal skeletal relationship but the chin, skeletal and soft tissue components, failed to develop in proportion to the skeletal base, resulting in marked protrusive (macrogenia) or retrusive (microgenia) facial profile.
Black hairy tongue  syndrome (BHT) is a condition of the tongue in which the small bumps on the tongue elongate with black or brown discoloration, giving a black and hairy appearance. The appearance may be alarming, but it is a harmless condition. Predisposing factors include smoking, xerostomia (dry mouth), soft diet, poor oral hygiene and certain medications. Management is facilitated by improving oral hygiene, especially scraping or brushing the tongue. Signs and symptoms
Hairy tongue largely occurs in the central part of the dorsal tongue, just anterior (in front) of the circumvallate papillae, although sometimes the entire dorsal surface may be involved. Discoloration usually accompanies hairy tongue, and may be yellow, brown or black. Apart from the appearance, the condition is typically asymptomatic, but sometimes people may experience a gagging sensation or a bad taste. There may also be associated oral malodor (intra-oral halitosis).The term "melanoglossia is also used to refer to there being black discolorations on the tongue without "hairs", which are also harmless and unrelated to black hairy tongue. Causes
The cause is uncertain, but it is thought to be caused by accumulation of epithelial squames and proliferation of chromogenic (i.e., color-producing) microorganisms. There may be an increase in keratin production or a decrease in normal desquamation (shedding of surface epithelial cells). Many people with BHT are heavy smokers. Other possible associated factors are poor oral hygiene, general debilitation, hyposalivation (i.e., decreased salivary flow rate), radiotherapy, overgrowth of fungal or bacterial organisms, and a soft diet.