|AIMS OF THE STUDY
To investigate whether or not there is association between the facial form and the form of the upper dental arch in adult males and females.
To find out the most frequent facial type (lateral and frontal) and dental arch form in Mosuli adults.
To obtain data in three dimensions (posterior-anterior and lateral) of craniofacial skeleton of Iraqi adults in Mosul city with normal class I occlusion, and to define the possible sex differences in craniofacial skeleton in the three dimensions.
Materials and Methods
The sample of this study involved students from Mosul University selected randomly from the following colleges (College of Dentistry, College of Law, College of Education, College of Agriculture and College of Arts). 448 clinically examined adult subjects, 100 were selected, and those who fit the criteria of clinical sample selection. Then cephalometric radiographs and impression were taken for them and only 95 (58 female 61%, 37 male 39%) were selected. The age of the sample ranged between (18 – 25) years old, They were normal healthy individuals of Mosul origin.
Criteria for Sample Specification:
Full complement of permanent dentition (excluding the third molars).
Bilateral Class I molar and canine occlusion
There are no:
History of previous orthodontic treatment.
Clinical detectable massive interproximal or occlusal caries.
Heavy dental restorations.
Fractured or crowned teeth or fixed prosthodontic therapy.
History of bad oral habits.
Facial disharmony (deformation).
Materials and Supplies:
A- Diagnostic Instruments : Dental mirrors, Kidney dishes , Cotton & Disinfectant solution
B-Impression and Cast Materials and Instruments : Wide bladed plaster spatula ,Rubber bowel ,Upper and lower perforated plastic orthodontic trays ,Irreversible hydrocolloid impression material & Dental stone.
C-Digitizing Equipments : Sharp pen, Metal ruler, Lab Top (hp) (Pentium IV), Compact disc ,Computer scanner (hp),.Software Planmeca dimaxis program .
The History and Clinical Examination:
The selected students were asked to tell information concerning their names, ages, history and then subjected to a thorough clinical examination to reassure the fulfillment of the required sample specifications
Construction of the Study Models:
Individual impression of the both dental arches was taken while the student was seated on a dental chair after instructing him / her about the procedure in order to cooperate with the researcher.
The Radiographic Technique:
Under standardized condition, two digital Cephalometrics were taken for each selected subject, one for lateral view and the other for frontal view. The subject was set in a standing position with his head fixed by two ear rods laterally and a locking nasal positioner was then secured against the bridge of the patient's nose to eliminate the possibility of rotation around ear rods in the sagittal plane and for future reference in subsequent exposures. Also it acts as a ruler caliber for the measurement to avoid magnification in the image, so the Frankfort horizontal plane is kept parallel to the floor. The subject was in centric occlusion during exposure.
1-Incisal Point: The midway point between the incisal edges of the two central incisors .
2-Canine Point: The cusp tip of the right and left permanent canines .
3- First Molars Point: The mesiobuccal cusp tip of the right and left permanent first molars .
4- Second Molars Point: The distobuccal cusp tip of the right and left second permanent molars .
Dental Arch Dimensions
Linear distances were measured on the copy of the study models for the maxillary dental arches to determine the dental arch width and length.
The linear dimensions are: (Figure 3)
Dental Arch Width
The breadth of dental arch is determined by measuring distance between the corresponding contralateral teeth Daskalogiannakis (2000)that includes:
1-Intercanine Distance (ICD): The linear distance between the cusp tip of the right and left permanent canines ( Warren and Bishara, 2001; Murad, 2008).
2-Inter First Molar Distance (IMD): The linear distance between the mesiobuccal cusp tip of the right and left permanent first molars (Salem, 2003).
3-Inter Second Molar Distance (I2MD); the linear distance between the distobuccal cusp tip of the right and left permanent second molars (Al-Shalabi, 2002).
B. Dental Arch Length:
1-Anterior Arch Length (Canine Vertical Distance) (C.V.D):
The vertical distance from the incisal point perpendicular to the intercanine distance at the cusp tip (Salem, 2003).
2-Posterior Arch Length (Molar Vertical Distance) (M.V.D):
The vertical distance from the incisal point perpendicular to the intermolar distance at the mesiobuccal cusp tip of permanent first molars (Ramdan, 2000; Salem, 2003).
3-Total Arch Length (TAL):
The vertical distance from the incisal point to the line joining the distobuccal cusp tips of the second permanent molars (Al-Shalabi, 2002).
Anterior arch length
Total arch length
Molar – vertical distance
Inter – canine distance
Inter – first molar distance
Inter – second molar distance
Figure (3) Dental Arch Measurements
Dental Arch Form: The size and shape of the arches have considerable implications in orthodontic diagnosis and treatment planning, affecting the space available, dental esthetics, and stability of the dentition (Uysala et al, 2005).
Computer Analysis of the Study Models
The models were directly placed on the glass window of the flat bed computer scanner with a metal ruler (Haralabakis et al , 2006). Distortion caused by the scanning procedure was corrected by the use of metal ruler that was scanned with each dental cast then corrected automatically by the software Dimaxis program (Mutinelli et al, 2004).
Figure(4) Scanning of the Dental Cast
Lateral Cephalometric Landmarks:
The following landmarks were used in this study
Point N (Nasion): The most anterior point of nasofrontal suture in the midsagittal plane.
Point Or (Orbitale): The lowest point in the inferior margin of the orbit.
Point Po (Anatomical Porion): The highest point on the bony external acoustic meatus.
Point ANS (Anterior Nasal Spine): The anterior tip of the sharp bony process of the maxilla at the lower margin of the anterior nasal opening .
Point Ba (Basion): The lowest point on the anterior rim of the foramen magnum in the mid-sagittal plane.