View source for Commonly used terms of relationship and comparison in dentistry



==Overview==
There are numerous '''commonly used terms of relationship and comparison''' that refer to different aspects of teeth and are frequently utilized in articles about [[dentistry]].  Many of them are included below as a sort of glossary to assist with understanding the many articles that include these types of words. 

==Terms==
[[Image:Directions.jpg|300px|thumb|right|This [[radiograph|X-ray film]] depicts the teeth in the lower right quadrant.  The arrows point in the following directions: red-distal, blue-mesial, yellow-coronal, peach-apical.]]
'''Anterior''' refers to the direction towards an individuals lips, as opposed to ''posterior'', which refers to the directions towards the back of an individual's head.  The term ''anterior teeth'' refers to [[incisor]]s and [[Canine tooth|canines]].

'''Apical''' refers to the direction towards the root tip(s) of a tooth, as opposed to ''coronal'', which refers to the direction towards the crown.  It may also refer to something relating to the roots, such as ''apical support''. his term is nearly synonymous with both ''cervical'' and ''gingival''.

'''Axial''' refers to a plane parallel to the surface of a tooth. For example, if a drill bur would be inserted into a tooth from any side (''proximal'', ''facial'' or ''lingual'', the depth of the hole is defined by the axial wall of the hole.

'''Buccal''' refers to the side of a tooth that is adjacent to (or the direction towards) the inside of the [[cheek]], as opposed to ''lingual'' or ''palatal'', which refer to the side of a tooth adjacent to (or the direction towards) the [[tongue]] or [[palate]], respectively. Although technically referring only to posterior teeth (where the cheeks are present instead of lips, use of this term may extend to all teeth, anterior and posterior), this term may be employed to describe the ''facial'' surface of (or directions in relation to) anterior teeth as well.

'''Cervical''', which simply means ''neck'' in [[Latin]] (as in [[cervical vertebrae]]), refers to the narrowing of the contours of the tooth surface at or near the [[cementoenamel junction|CEJ]], where the crown meets the root. When referring to direction in relation to entities on or of the crown, it is nearly synonymous with both ''apical'' and ''gingival''.

'''Coronal''' refers to the direction towards the crown of a tooth, as opposed to ''apical'', which refers to the direction towards the tip(s) of the root(s). It may also refer to something relating to the crown, such as ''coronal forces''.

'''Distal''' refers to the direction towards the last tooth in each quadrant of a dental arch, as opposed to ''mesial'', which refers to the direction towards the anterior [[dental midline|midline]]. Each tooth can be described as having a distal surface and, for ''posterior'' teeth, a ''distobuccal (DB)'' and a ''distolingual (DL)'' corner or [[cusp (dentistry)|cusp]].

[[Image:Occlusal of Mr. M's Complete Denture - mod.jpg|300px|thumb|right|This photo shows an occlusal view of a [[denture|complete maxillary denture]].  The green line, indicating the [[dental midline]], is the defining line when it comes to mesial-distal direction.  The blue arrow, which indicates a mesial direction, applies to the opposite side as well up until the green line.  The red arrow is directly buccal to the left first maxillary molar, and the patient's name (Martin) label is embedded in the [[resin]] directly palatal to the same tooth.]]
'''Facial''' refers to the side of a tooth that is adjacent to (or the direction towards) the inside of the [[cheek]] or [[lip]]s, as opposed to ''lingual'' or ''palatal'', which refer to the side of a tooth adjacent to (or the direction towards) the [[tongue]] or [[palate]], respectively.  This term is an [[umbrella term]] for both the term ''buccal'' and ''labial''.

'''Gingival''' refers to the direction towards the [[gingiva]], synonymous with ''cervical'' and similar to apical.  However, locations on teeth already more ''apical'' to the interface of the crown and root, referred to as the [[cementoenamel junction|CEJ]], tend not to be described using this term, as it would lead to confusion, as the exact definition is ambiguous.  Additionally, this term would not be used when referring to a tooth ''[[ex vivo]]''.

'''Incisal''' refers either to the direction towards the biting edge of ''anterior'' teeth or to something relating to this edge, such as the terms ''incisal guidance'' or ''incisal edge''. This is the sister term to ''occlusal'', which related to the analogous location on ''posterior'' teeth.

'''Inferior''', as usual, refers to the direction towards the feet of an human's body, as opposed to ''superior'', which refers to the direction towards the head.  However, use of these terms should enjoy only limited usage when discussing features of a tooth, as, for example, something more inferior on a [[mandible|mandibular]] tooth will be situated more superior on a [[maxilla]]ry tooth, as they exhibit an inverted relationship.  It is for this reason that the terms ''coronal'' an ''apical'' are substituted.

'''Labial''' refers to the side of a tooth that is adjacent to (or the direction towards) the inside of the [[lip]], as opposed to ''lingual'' or ''palatal'', which refer to the side of a tooth adjacent to (or the direction towards) the [[tongue]] or [[palate]], respectively.  Although technically referring only to anterior teeth (where the lips are present instead of cheeks, use of the term ''buccal'' may extend to all teeth, anterior and posterior.)

'''Lingual''' refers to the side of a tooth adjacent to (or the direction towards) the tongue, as opposed to ''buccal'', ''labial'' or ''facial'' which refer to the side of a tooth adjacent to (or the direction towards) the inside of the cheek or lips, respectively.  Although this term is technically specific to the [[mandible]], it enjoys extensive use in reference to the [[maxilla]] as well.

'''Mandibular''' refers to entities related to the [[mandible]].

'''Marginal''' may be used to refer to a number of different 'margins' that are involved in dentistry. The edge of tooth structure that is prepared to meet the edge of a prosthetic [[crown (dentistry)|crown]] is called a margin, as is the aforementioned edge of the crown; an example of this usage would be "a poorly fitting crown might exhibit ''marginal'' leakage."  The [[gingiva]] and [[alveolar bone|bone]] that abut the teeth are referred to as 'marginal', as in ''marginal'' [[periodontitis]].  The bulk of tooth structure on the ''occlusal'' surface at the point of contact of posterior teeth is referred to as the ''marginal'' ridge.

'''Maxillary''' refers to entities related to the [[maxilla]].

[[Image:MO inlay of 3.jpg|200px|thumb|right|This photo shows teeth #2-5. Tooth #3, the upper right first [[molar (tooth)|molar]], has an MO (mesial-occlusal) [[gold]] [[inlays and onlays|inlay]].  This molar is both posterior, as well as distal, to than the [[premolar]]s in front of it.]]
'''Mesial''' refers to the direction towards the anterior [[dental midline|midline]] is a dental arch, as opposed to ''distal'', which refers to the direction towards the last tooth in each quadrant. Each tooth can be described as having a mesial surface and, for ''posterior'' teeth, a ''mesiobuccal (MB)'' and a ''mesiolingual (MB)'' corner or [[cusp (dentistry)|cusp]].

'''Occlusal''' refers either to the direction towards the biting surface of ''posterior'' teeth or to something relating to this surface, such as the terms ''occlusal interference'' or ''occlusal surface''. This is the sister term to ''incisal'', which related to the analogous location on ''anterior'' teeth. Restorations are designated by their location on a tooth, and abbreviated as such. Thus, for example, an [[amalgam]] restoration on the distal-occlusal of a tooth would be termed a ''DO amalgam''.

'''Palatal''' refers to the side of a tooth adjacent to (or the direction towards) the [[palate]], as opposed to ''buccal'', ''labial'' or ''facial'' which refer to the side of a tooth adjacent to (or the direction towards) the inside of the cheek or lips, respectively.  This term is strictly used in the [[maxilla]].

'''Posterior''' refers to the direction towards the back of an individual's head, as opposed to ''anterior'', which refers to the directions towards an individuals lips.  The term ''posterior teeth'' refers to [[premolar]]s and [[Molar (tooth)|molars]].

'''Proximal''' is an [[umbrella term]] which includes both ''mesial'' and ''distal'', such as when referring to the ''proximal surfaces'' of teeth.

'''Superior''', as usual, refers to the direction towards the head of an human's body, as opposed to ''inferior'', which refers to the direction towards the feet. However, use of these terms should enjoy only limited usage when discussing features of a tooth, as, for example, something more superior on a [[mandible|mandibular]] tooth will be situated more inferior on a [[maxilla]]ry tooth, as they exhibit an inverted relationship. It is for this reason that the terms ''coronal'' and ''apical'' are substituted.

==References==
Major M. Ash, Stanley Nelson. WHEELER'S DENTAL ANATOMY, PHYSIOLOGY AND OCCLUSION, 8th edition.

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[[Category:Dentistry definitions]]

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