The trapezoidal flap is created after a ∏ - shaped incision, which is formed by a horizontal incision along the gingivae, and two oblique vertical releasing incisions extending to the buccal vestibule. The vertical releasing incisions always extend to the interdental papilla and never to the center of the labial or buccal surface of the tooth. This ensures the integrity of the gingiva proper, because if the incisionwere to begin at the center of the tooth, contraction after healing would leave the cervical area of the tooth exposed. (Fig 1. a, b)
Fig. 1. a,b. Trapezoidal flap. a. Diagrammatic illustration. b. Clinical photograph. This type of flap is used in large surgical procedures, providing adequate access
A satisfactory surgical field is ensured when the incision extends at least one or two teeth on either side of the area of bone removal. The fact that the base of the resulting flap is broader than its free gingivalmargin ensures the necessary adequate blood supply for the healing process. The trapezoidal flap is suitable for extensive surgical procedures, especially when the triangular flap would not provide adequate access.
Advantages. Provides excellent access, allows surgery to be performed on more than one or two teeth, produces no tension in the tissues, allows easy reapproximation of the flap to its original position and hastens the healing process.
Disadvantages. Produces a defect in the attached gingiva (recession of gingiva).
Triangular Flap
This flap is the result of an L-shaped incision (Fig 2. a, b)
Fig. 2. a, b. Triangular flap resulting from L-shaped incision. a. Diagrammatic illustration. b. Clinical photograph. Indicated in surgical removal of root tips, small cysts and in apicoectomies
with a horizontal incision made along the gingival sulcus and a vertical or oblique incision. The vertical incision begins approximately at the vestibular fold and extends to the interdental papilla of the gingiva. The triangular flap is performed labially or buccally on both jaws and is indicated in the surgical removal of root tips, small cysts, and apicoectomies.
Advantages. Ensures an adequate blood supply, satisfactory visualization, very good stability and reapproximation; it is easily modified with a small releasing incision, or an additional vertical incision, or even lengthening of the horizontal incision.
Disadvantages. Limited access to long roots, tension is created when the flap is held with a retractor, and it causes a defect in the attached gingiva.
Envelope Flap
This type of flap is the result of an extended horizontal incision along the cervical lines of the teeth. The incision is made in the gingival sulcus and extends along four or five teeth. The tissue connected to the cervical lines of these teeth and the interdental papillae is thus freed. The envelope flap is used for surgery of incisors, premolars and molars, on the labial or buccal and palatal or lingual surface
Fig. 3. a, b. Single-sided (envelope) flap created by a single horizontal incision along the cervical lines of the teeth. a. Diagrammatic illustration (buccal). b. Clinical photograph (palatal). It is primarily used in surgical procedures involvingthe cervical region of teeth buccally, and palatally in cases of removal of impacted teeth, as well as apicoectomies (palatal root of molar)
and is usually indicated when the surgical procedure involves the cervical lines of the teeth labially (or buccally) and palatally (or lingually), apicoectomy (palatal root), removal of impacted teeth, cysts, etc.
Advantages. Avoidance of vertical incision and easy reapproximation to original position.
Disadvantages. Difficult reflection (mainly palatally), great tension with a risk of the ends tearing, limited visualization in apicoectomies, limited access, possibility of injury of palatal vessels and nerves, defect of attached gingiva.
Semilunar Flap
This flap is the result of a curved incision, which begins just beneath the vestibular fold and has a bowshaped course with the convex part towards the attached gingiva (Fig 4. a, b).
Fig. 4. a, b. Semilunar flap. a. Diagrammatic illustration. b. Clinical photograph. It is used in apicoectomies and removal of small cysts and root tips
The lowest point of the incisionmust be at least 0.5 cm fromthe gingivalmargin, so that the blood supply is not compromised. Each end of the incision must extend at least one tooth over on each side of the area of bone removal. The semilunar flap is used in apicoectomies and removal of small cysts and root tips.
Advantages. Small incision and easy reflection, no recession of gingivae around the prosthetic restoration, no intervention at the periodontium, easier oral hygiene compared to other types of flaps.
Disadvantages. Possibility of the incision being performed right over the bone lesion due to miscalculation, scarringmainly in the anterior area, difficulty of reapproximation and suturing due to absence of specific reference points, limited access and visualization, tendency to tear.
