What D7991 means

D7991 covers a coronoidectomy. "D" is dental, "79" is this oral surgery area, and "91" is this coronoidectomy. The 'coronoid process' is a thin, triangular projection of bone at the top of the mandibular ramus (the upright back portion of the lower jaw), at the front (anterior to the condyle, which is the other top projection that forms the jaw joint). The temporalis muscle (a major chewing/jaw-closing muscle) attaches to the coronoid process. '-ectomy' means surgical removal. So a coronoidectomy is the surgical removal of the coronoid process. So D7991 is removing the coronoid process of the lower jaw.

So it's surgically removing the coronoid process — a bony projection of the lower jaw — done when it's restricting the jaw's movement.

A coronoidectomy is performed when the coronoid process is causing a problem — typically restricting the mouth from opening (limiting jaw movement). The main indications include: coronoid hyperplasia — an overgrowth/enlargement of the coronoid process (it grows too long); the enlarged coronoid impinges against the zygomatic bone/arch (cheekbone) when the mouth opens, mechanically blocking jaw opening — causing progressively limited mouth opening; removing the overgrown coronoid (coronoidectomy) relieves this impingement and improves opening; restricted opening from other causes — situations where the coronoid contributes to limited movement (e.g., after trauma, with scarring/ankylosis involving the coronoid, or other conditions causing the coronoid to restrict motion) — removing it improves jaw mobility; and as part of other procedures — a coronoidectomy is sometimes done as part of a larger procedure (e.g., to improve access or release the jaw in TMJ ankylosis surgery, or in conjunction with reconstruction). Removing the coronoid process releases the restriction (and detaches the temporalis muscle's pull at that point), improving the jaw's ability to open and move. It's performed by an oral and maxillofacial surgeon. These procedures treat a functional condition (restricted jaw movement), so medical coverage may apply. This code is in the oral surgery area (D7900-D7999). Documentation supports the claim.

When it's typically used

D7991 is reported for a coronoidectomy — surgically removing the coronoid process of the mandible — done to treat conditions where the coronoid restricts jaw movement, most notably coronoid hyperplasia (overgrowth impinging on the cheekbone and blocking mouth opening) or other situations where the coronoid limits opening, to improve jaw opening/movement. It's sometimes done as part of a larger procedure.

How much does D7991 cost?

A coronoidectomy is a surgical procedure (often under general anesthesia) — its cost reflects the surgical removal (and varies with whether it's done alone or as part of a larger procedure). Sample fee-schedule values are in the mid-three-figure to four-figure range (varying by region/case). As it treats a functional condition (restricted jaw movement), medical coverage may apply. Verify your specific coverage.

Is D7991 covered by insurance?

A coronoidectomy treats a functional condition (a restriction of jaw movement, e.g., from coronoid hyperplasia limiting mouth opening), so it may be covered under medical benefits (check both medical and dental plans). Documentation of the condition (the coronoid hyperplasia/impingement or other cause, the limited opening — often with imaging and opening measurements) and the procedure supports the claim. When done as part of a larger procedure, it's coded in that context. Verifying coverage helps.

What the coronoid process is

It's a bony jaw projection where a chewing muscle attaches, and understanding this clarifies the code.

Understanding the coronoid process clarifies D7991. The mandible's ramus (the upright back portion of the lower jaw) has two projections at its top: the condyle (posterior) — the rounded projection at the back that forms the temporomandibular joint (TMJ) with the skull; and the coronoid process (anterior) — a thin, triangular, pointed projection at the front-top of the ramus. The temporalis muscle — a large, fan-shaped chewing muscle on the side of the head — attaches to the coronoid process; this muscle elevates (closes) and helps position the jaw. The coronoid sits just behind the cheekbone (zygomatic arch); when the mouth opens, the coronoid normally moves without hitting the cheekbone.

A coronoidectomy removes this coronoid process. Because the coronoid is a projection that the temporalis attaches to (rather than a part of the main jaw body or the joint), it can be removed to relieve a restriction it's causing — detaching the temporalis at that point and eliminating the bony projection. (Removing the coronoid doesn't remove the jaw joint, which is the condyle — a separate structure.) So the coronoid process is a removable jaw projection. Understanding this helps patients see that the mandible's ramus (the upright back portion of the lower jaw) has two projections at its top — the condyle (posterior, the rounded projection at the back forming the TMJ with the skull) and the coronoid process (anterior, a thin, triangular, pointed projection at the front-top of the ramus) — the temporalis muscle (a large, fan-shaped chewing muscle on the side of the head) attaching to the coronoid process (this muscle elevating/closing and helping position the jaw), the coronoid sitting just behind the cheekbone/zygomatic arch (so when the mouth opens, the coronoid normally moves without hitting the cheekbone) — so a coronoidectomy removes this coronoid process (which, being a projection the temporalis attaches to rather than a part of the main jaw body or the joint, can be removed to relieve a restriction it's causing, detaching the temporalis at that point and eliminating the bony projection, without removing the jaw joint/condyle, a separate structure).

Coronoid hyperplasia and restricted opening

An overgrown coronoid blocks jaw opening, and understanding this clarifies the main indication.

Understanding coronoid hyperplasia clarifies the main indication for D7991. Coronoid hyperplasia is an overgrowth (enlargement/elongation) of the coronoid process — the coronoid grows abnormally long. The problem this causes is mechanical: as the coronoid enlarges, when the mouth opens, the overgrown coronoid impinges against (bumps into) the zygomatic bone/arch (the cheekbone) — and this bony collision blocks the jaw from opening further. The result is progressively limited mouth opening (a restriction that often develops gradually, can be bilateral, and limits how wide the patient can open) — a mechanical obstruction from the coronoid hitting the cheekbone.

This is distinct from TMJ problems or muscle problems — here the limitation is from the coronoid bone itself impinging. The treatment is a coronoidectomy — removing the overgrown coronoid process (on the affected side(s)) eliminates the impingement, so the jaw can open freely again — restoring/improving the mouth opening. (Post-operative physiotherapy/jaw exercises help regain and maintain the opening.) Beyond hyperplasia, the coronoid can also restrict opening in other settings (trauma, scarring, ankylosis), where removing it similarly helps. So coronoid hyperplasia restricts opening, and coronoidectomy relieves it. Understanding this helps patients see that coronoid hyperplasia is an overgrowth (enlargement/elongation) of the coronoid process (the coronoid growing abnormally long), causing a mechanical problem — as the coronoid enlarges, when the mouth opens the overgrown coronoid impinges against (bumps into) the zygomatic bone/arch (the cheekbone), and this bony collision blocks the jaw from opening further, resulting in progressively limited mouth opening (a restriction that often develops gradually, can be bilateral, and limits how wide the patient can open, a mechanical obstruction from the coronoid hitting the cheekbone) — distinct from TMJ or muscle problems (here the limitation being from the coronoid bone itself impinging) — so the treatment is a coronoidectomy (removing the overgrown coronoid process on the affected side(s) eliminates the impingement so the jaw can open freely again, restoring/improving the mouth opening, with post-operative physiotherapy/jaw exercises helping regain and maintain it), and beyond hyperplasia the coronoid can also restrict opening in other settings (trauma, scarring, ankylosis) where removing it similarly helps.

Improving jaw movement

Removing the coronoid restores opening, and understanding this clarifies the goal.

Understanding the goal clarifies D7991. The purpose of a coronoidectomy is to improve the jaw's movement — specifically the mouth opening — by removing the coronoid process that's restricting it. When the coronoid is the cause of (or contributor to) limited opening — whether by overgrowth/impingement (hyperplasia) or by other mechanisms (scarring, ankylosis involving the coronoid, etc.) — removing it eliminates that restriction: the bony impingement/obstruction is gone (so the jaw can move past where the coronoid was blocking it); and the temporalis muscle's pull at the coronoid is released (which, if a tight/restricting temporalis was contributing, also helps free the jaw).

The result is improved jaw opening and movement. Because regaining function also depends on the soft tissues and the patient's effort, post-operative jaw physiotherapy/exercises are typically important — to stretch and maintain the improved opening as healing occurs (otherwise scarring could limit the gain). So the coronoidectomy, combined with rehabilitation, improves the mouth opening. So removing the coronoid improves jaw movement. Understanding this helps patients see that the purpose of a coronoidectomy is to improve the jaw's movement (specifically the mouth opening) by removing the coronoid process that's restricting it — when the coronoid is the cause of (or contributor to) limited opening (whether by overgrowth/impingement in hyperplasia or by other mechanisms like scarring or ankylosis involving the coronoid), removing it eliminating that restriction (the bony impingement/obstruction gone, so the jaw can move past where the coronoid was blocking it, and the temporalis muscle's pull at the coronoid released, which, if a tight/restricting temporalis was contributing, also helps free the jaw) — the result being improved jaw opening and movement — and because regaining function also depends on the soft tissues and the patient's effort, post-operative jaw physiotherapy/exercises typically being important (to stretch and maintain the improved opening as healing occurs, otherwise scarring could limit the gain), so the coronoidectomy combined with rehabilitation improves the mouth opening.

Where D7991 fits in the codes

D7991 is a distinct jaw-bone procedure code, and understanding this clarifies the coding.

Understanding where D7991 sits clarifies the coding. D7991 is among the later oral surgery codes (in the D7900s). It addresses a specific bony procedure of the mandible — removing the coronoid process. It's distinct from the nearby codes: the salivary codes (D7980-D7983); emergency tracheotomy (D7990); coronoidectomy (D7991, this code); and the implant/graft/appliance and unspecified codes (D7993-D7999). It's also distinct from the orthognathic osteotomies (D7940-D7949, which cut/reposition the jaws) and the TMJ procedures (D7810-D7899, which address the jaw joint) — a coronoidectomy specifically removes the coronoid process (a different bony structure, for a different purpose — relieving a restriction).

Note it's related conceptually to jaw-movement problems: while TMJ procedures address the joint and the orthognathic codes reposition the jaws, the coronoidectomy addresses a coronoid-related restriction of opening — and it may be done alone (e.g., for isolated coronoid hyperplasia) or as part of a larger procedure (e.g., in TMJ ankylosis release or reconstruction, where freeing the coronoid helps restore movement). The surgeon codes D7991 for removing the coronoid process. So D7991 is the coronoidectomy among the oral surgery codes. Understanding this helps patients see that D7991 is among the later oral surgery codes (in the D7900s), addressing a specific bony procedure of the mandible (removing the coronoid process), distinct from the nearby codes (the salivary codes D7980-D7983, emergency tracheotomy D7990, coronoidectomy D7991 this code, and the implant/graft/appliance and unspecified codes D7993-D7999) and from the orthognathic osteotomies (D7940-D7949, which cut/reposition the jaws) and the TMJ procedures (D7810-D7899, which address the jaw joint) — a coronoidectomy specifically removing the coronoid process (a different bony structure, for a different purpose — relieving a restriction) — related conceptually to jaw-movement problems (while TMJ procedures address the joint and the orthognathic codes reposition the jaws, the coronoidectomy addresses a coronoid-related restriction of opening), done alone (e.g., for isolated coronoid hyperplasia) or as part of a larger procedure (e.g., in TMJ ankylosis release or reconstruction, where freeing the coronoid helps restore movement), coded for removing the coronoid process.

Frequently asked questions

What is the D7991 dental code?

It's a coronoidectomy — the surgical removal of the coronoid process of the mandible (a thin, triangular bony projection at the top-front of the lower jaw's ramus, where a chewing muscle attaches). It's done to treat conditions where the coronoid restricts jaw movement — most notably coronoid hyperplasia (overgrowth) — removing it to improve mouth opening/movement.

What is the coronoid process?

A thin, triangular, pointed projection of bone at the top-front of the mandibular ramus (the upright back part of the lower jaw), in front of the condyle (which forms the jaw joint). The temporalis muscle (a chewing/jaw-closing muscle) attaches to it. The coronoid sits just behind the cheekbone (zygomatic arch). Removing it doesn't affect the jaw joint (the condyle, a separate structure).

What is coronoid hyperplasia?

An overgrowth/elongation of the coronoid process — it grows abnormally long. The problem is mechanical: as it enlarges, when the mouth opens the overgrown coronoid bumps into the cheekbone (zygomatic arch), blocking the jaw from opening further. This causes progressively limited mouth opening. Removing the overgrown coronoid (coronoidectomy) relieves the impingement.

How does removing it help?

It eliminates the restriction the coronoid was causing — the bony impingement/obstruction is gone (so the jaw can open past where the coronoid was blocking it), and the temporalis muscle's pull at the coronoid is released. The result is improved jaw opening and movement. Post-operative jaw physiotherapy/exercises are typically important to regain and maintain the opening.

Is it done alone or with other procedures?

Either. It can be done alone — e.g., for isolated coronoid hyperplasia causing limited opening. It's also done as part of a larger procedure — for example, in TMJ ankylosis release or jaw reconstruction, where removing/freeing the coronoid helps restore the jaw's movement. The surgeon decides based on the condition.

What does it cost, and is it covered?

It's a surgical procedure (often under general anesthesia) — cost in the mid-three-figure to four-figure range, varying by case (and whether it's alone or part of a larger procedure). As it treats a functional condition (restricted jaw movement), medical coverage may apply (check both plans; documentation of the limited opening and cause helps). Verify your specific coverage.

This page is an independent, plain-language explanation for general information only. It is not billing, coding, or clinical advice. For the official CDT descriptor and current-year wording, refer to the American Dental Association.