Molars

Permanent molars are the most posteriorly placed posterior teeth of the permanent dentition, distinguished by their position distal to the premolars.
These molars are the largest teeth in the dentition, allowing significant functionality during mastication.
Typically, each dental arch has six molars, with three in each quadrant, assuming all have erupted.
Three types of molars:
First molars (commonly known as 6-year molars)
Second molars (known as 12-year molars)
Third molars (commonly referred to as wisdom teeth)
The eruption of the third molars typically signifies the conclusion of jaw growth, occurring around ages 17-21.

The eruption sequence for all three types of molars occurs in order, distal to the primary second molars, following the eruption and functionality of primary teeth.
Permanent molars are classified as nonsuccedaneous because they do not replace any primary teeth.

Permanent molars have the largest and strongest crowns in the permanent dentition, and work closely with premolars to grind food efficiently during mastication.
Their grinding function is facilitated by wide occlusal surfaces with prominent cusps, which are notably more numerous than those found in other teeth.
Crown outline characteristics:
Viewed from the buccal or lingual, molars' crown outlines are trapezoidal or four-sided.
Proximally, maxillary molars display a trapezoidal outline while mandibular molars exhibit a rhomboidal outline.

The first molar is the largest, with the second and third molars being progressively smaller.
Molars possess an exceptionally large crown compared to other permanent teeth, though their crowns are shorter occlusocervically than the crowns of anterior teeth.

Each buccal surface of a molar features a prominent cervical ridge in the cervical one-third that runs mesiodistally (MD).
The occlusal surface has three or more cusps, with at least two being buccal cusps; however, no buccal developmental depressions are present.
The occlusal table of molars is bordered by cusp ridges and marginal ridges, and grooves/pits appear on the occlusal surfaces of both maxillary and mandibular molars, as well as on the lingual surfaces of maxillary molars and buccal surfaces of mandibular molars.

Molars possess multi-rooted structures, with maxillary molars typically having three roots (trifurcated) and mandibular molars having two roots (bifurcated).
The teeth originate with a single root structure at the base of the crown, known as the root trunk, from which the roots branch out, enhancing periodontal support due to multiple roots.

The removal of third molars is common during adolescence, yet remains a source of controversy. Approximately 25% of patients require extraction of their third molars before age 25, often despite lacking awareness of potential complications.
More than 40% of adults without childhood extractions of third molars may face infections, caries, cyst formation, or periodontal disease by age 45 necessitating extraction.
Surgical removal risks increase by 30% in adults compared to adolescents, thus an evaluation of third molars at age 25 is advisable.

In periodontitis, molar root features such as furcations and root concavities can lose periodontal support, resulting in varying degrees of furcation involvement.
Biofilm deposits may accumulate in exposed furcations leading to further periodontal diseases, with molars exhibiting a higher incidence of loss to periodontal disease compared to single-rooted teeth.

Mulberry Molars: Children with congenital syphilis may exhibit molars with abnormally shaped occlusal surfaces characterized by berry-like nodules (enamel tubercles) rather than defined cusps.
Enamel Pearl: Found chiefly on the buccal surfaces of second molars, these enamel deposits are tapered and extend into root furcation areas, present in over 28% of maxillary molars and 17% of mandibular molars; they cannot be removed through traditional instrumentation.
Dilaceration: This condition of root bending or distortion complicates extractions and endodontic treatments.
Root Fusion: Causes deep developmental grooves where molar roots fuse, which can trap deposits inaccessible to periodontal treatments or homecare. Post-third molars, the highest prevalence of root fusion occurs primarily in maxillary second molars, with women showing a higher incidence than men.

Permanent maxillary molars typically erupt between 6 months and 1 year after the corresponding permanent mandibular molars, making them often the first permanent teeth to appear in the maxillary arch.
They are the largest and strongest teeth in the maxillary arch but are shorter occlusocervically compared to the crowns of anterior teeth.

Eruption & Characteristics: Table indicates the universal and international numbers, general/crown features, and distinct characteristics of maxillary first, second, and third molars, including:
First molar: Largest tooth; four major cusps; oblique ridge present.
Second molar: Smaller than first; three or four cusps, heart-shaped or rhomboidal crown outline.
Third molar: Smallest, variable in form, often has a heart-shaped crown outline with less furcation development.