Yasuhiko Hiranuma

Strain distribution during separation of the pterygomaxillary suture by osteotomes: Comparison between Obwegeser's osteotome and Swan's neck osteotome

In the Le Fort I type osteotomy, separation of the pterygomaxillary suture is a dangerous manoeuvre which must be carried out during the surgical procedure. To determine the osteotome best suited for safe separation of the pterygomaxillary suture, we measured the strain distribution over the surrounding bone structures during the osteotomy, employing two types of osteotomes. In both the Obwegeser osteotome group and swans neck osteotome group, a large strain was measured at the medial pterygoid plate on the side of osteotome application. The intensity of the strain at the medial pterygoid plate was higher in the Obwegeser osteotome group than in the swans neck group. With the Obwegeser osteotome which is routinely and commonly used in orthognathic surgery, safe separation of the suture cannot be accomplished unless the blade is correctly applied to the suture and superoposterior compression of the pterygoid process is avoided.

Calcifying odontogenic cyst immunohistochemical detection of keratin and involucrin in cyst wall.

Calcifying odontogenic cysts (COC) were immunohistochemically described using different keratin proteins and involucrin as well as histopathology. The cystic lining epithelium was composed of calcifying, keratinizing, squamous, and columnar epithelial cells, and included calcified masses of irregular shape and various size as well as ghost cells. Calcifying epithelium gave negative or only trace staining for keratins detected with low molecular keratin (PKK1), but were regularly positive with high molecular keratin (KL1) and polyclonal antibody for keratin (TK). They were occasionally positive for involucrin. The cells located in the periphery of the calcified masses had a particular abundance of high molecular weight and total keratins (KL1 and TK). Calcified bodies and ghost cells were devoid of any immunoreactivity. Squamous epithelium was relatively similar to that of normal squamous cell epithelium in the oral mucosa. It were most commonly found in columnar cystic epithelial cells which displayed intense staining with all immunoreagents. It is postulated that such epithelial cells may have a strong potentiality to transform into ghost cells or to undergo metaplasia. They may develop altered synthesis of homogenous acellular materials and finally become transformed into calcifying epithelium containing dystrophic calcified masses.