|A) Brief resume of the intended work:
Need of the study
Canine guidance is disocclusion by the canines of all other teeth in lateral excursion. The basis of canine protected occlusion theory is that canines act as natural stress breakers to guide the mandible.
Reported studies on canine protected occlusion were recorded with canines in edge to edge position, ignoring the functional zone between the intercuspal & edge to edge position.
Review of literature
A study claimed that with canine guided occlusion, functional loading is directed axially by limiting the contacts of posterior teeth by steeper inclines of canine. This results in chewing stroke in more sagittal direction and mastication occurs with pounding motion1 .
A study concluded that canine guided occlusion is associated with low degree of Frankfort-mandibular plane angle and an increased biting force while group function is associated with high degree of Frankfort-mandibular angle and low biting force2 .
A study recorded the functional range of tooth contacts & the amount & nature of contact of natural teeth in lateral glide movement reported that earlier studies on similar aspects have ignored the functional zone between the intercuspal & edge to edge position 3.
A study done on classification system of canine guided & group function occlusal schemes concluded that the static contact classification system is questionable & concluded that a new classification system of occlusal guidance is required considering the dynamic contacts 4.
Objective of the study :
- To determine the range of functional zone between the intercuspal positions & edge to edge position.
-To determine the range of incomplete disocclusion of posterior teeth in canine guided occlusion.
- To determine the range of complete disocclusion of posterior teeth in canine guided occlusion.
B) Material and methods:
Source of data
A total of thirty five subjects will be selected from the student population and the subjects reporting to the out patient department of A B Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore , India.
Method of collection of data [ including sampling procedure, if any]
The study is planned as follows :
1. Selection of subjects.
2. Measuring range of incomplete & complete disocclusion.
3. Statistical analysis of the obtained data.
Criteria for selection :
Subjects showing canine guided occlusion.
Subjects with full complement of teeth excluding third molars.
No history of orthodontic treatment.
Angle’s class 1 molar & canine relation.
All subjects above the age of 18 years, as facial growth would be essentially complete.
No history of congenital facial abnormality and facial surgery.
Criteria for exclusion:
Subjects showing group function type of guidance.
Severly attrited or compromised canines.
Subjects with fixed or removable prosthesis.
Poor neuromuscular coordination.
Generalized decay or periodontal pathology.
The following armamentarium would be used
Description of the study
-Maxillary & mandibular midlines will be marked in centric occlusion with marker pen in the patient’s mouth.
-With the help of graduated scale, lines from 1mm to 5mm will be marked on maxillary central incisor with marker pen.
- A loop of dental floss will be extended from distal surface of 2nd molar to mesial surface of 1st premolar in the subject’s oral cavity.
-Subjects will be asked to make 1mm lateral movement
- Dental floss will be withdrawn anteriorly holding the two ends of the floss in this lateral excursive position.
- If the floss would hold its position, it will indicate absence of disocclusion.
- This procedure will be repeated in every 1mm lateral movement till edge to edge relation of the maxillary & mandibular canine is achieved.
- The range of incomplete disocclusion, complete disocclusion & the range of functional zone between intercuspal till edge to edge position will be recorded.
- Statistical analysis will be done by calculating the mean range and standard deviation of the obtained data.
Does the study contain any investigation or intervention to be conducted on patients or other human beings or animals?
Has ethical clearance been obtained from your institution in case of 7.3?
Yes. (Ethical Clearance Letter Enclosed)
C)List of references:
1. D Blake McAdam.Tooth loading and cuspal guidance in canine and group function occlusions. J Prosthet Dent 1976;35:283-90
2.Girard J. DiPietro. A study of occlusion as related to the Frankfort-mandibular plane angle. J Prosthet Dent 1977;38:452-58
3. A. Yaffe & J. Ehrlich. The functional range of tooth contact in lateral gliding movements. J Prosthet Dent 1987;57:730-33.
4. Takahiro Ogawa, Tatsuo Ogimoto & Kiyoshi Koyano. Pattern of occlusal contacts in lateral positions: Canine protection & group function validity in classifying guidance pattern. J Prosthet Dent 1998;80:67-74.