Geometric Outline of Teeth PDF

Physiological Significance Of the Crown outline In general, all aspects of the tooth crown except the incisal or occlusal aspects may be outlined as one of the three geometric figures of large or small size. These figures are trapezoid, triangular and rhomboi...

Physiological Significance Of the Crown outline In general, all aspects of the tooth crown except the incisal or occlusal aspects may be outlined as one of the three geometric figures of large or small size. These figures are trapezoid, triangular and rhomboid.  The labial or buccal (facial) and lingual surfaces of all teeth Trapezoid The short side is cervically and the long side is incisally or occlusally. Significances of the trapezoid outline Provides contact between the teeth at certain areas. Provides interproximal spaces. Provides spacing between the roots of neighboring teeth. 1- Provides contact between the teeth. This gives stabilization of the dental arch, protect the inter-dental soft tissue and prevent food accumulation. 2- Provides inter-proximal spaces which contain inter- proximal gingival tissues. 3- Spacing between the roots of neighboring teeth to allow sufficient supporting alveolar bone, periodontal ligament and blood and nerve supply.  The proximal surfaces of anterior teeth Triangle The base is cervical and the apex is incisal.  Significances of the triangle outline 1- A wide base adding strength to the crown. 2- A tapered labial and lingual outlines converging to the incisal ridges to facilitate cutting through food materials.  The proximal surface of maxillary posterior teeth Trapezoid The long side is cervical and the short side is occlusal.  Significances of the trapezoid outline 1- A wide base gives strength to the crown 2- The occlusal surface is constricted and so the tooth can be forced into food material more easily. 3- This form allows the tooth to be self-cleaning.  The proximal surface of mandibular posterior teeth Rhomboid For the lingual inclination of lower teeth. The occlusal surface however is constricted compared to the crown base.  Significances of the rhomboid outline 1- The occlusal surface is more constricted than the cervical so, it is similar in this part to the maxillary posterior teeth and serves all the 3 points mentioned before AND 2- The crown inclines slightly lingual to the root bases bringing the cusps into proper occlusion with the maxillary teeth. 3- Make the long axis of the upper and lower teeth parallel to each other; this will prevent hit and clash of cusps during function. ☻ Allows for establishment of the intercusp relation between the opposing teeth in centric occlusal relation. This arrangement prevents traumatic occlusion. Functional tooth form that has been lost can be approximated by restorative treatment in many cases. Restorations, crowns, bridges, partial or complete.dentures or implants may be used