Orthodontics II: Main Exam, 14 December 2018
Mount Kenya University · Department of Dental Sciences · Diploma in Dental Technology · BDS2205
Orthodontics II past paper from Mount Kenya University 2018-2019 with model answers for BDS2205 unit.
Instructions: Answer ALL questions in section A and answer ANY TWO questions from
Section A ANSWER ALL THE QUESTIONS
1.
- a) Outline two requirements of an orthodontic spring. (2 marks)Model answer
- Requirements of an orthodontic spring
- a. Force magnitude – must be sufficient to move teeth but not exceed tissue tolerance.
- b. Directionality – must act in the desired vector to achieve the planned tooth movement.
- b) Explain five factors which may affect anchorage in removable orthodontics. (4 marks)Model answer
- Factors affecting anchorage in removable orthodontics
- a. Tooth selection – number and type of teeth used for anchorage.
- b. Occlusal contacts – inter‑arch contacts that resist movement.
- c. Soft tissue resistance – lip, cheek, and tongue forces.
- d. Appliance design – shape and fit of the retainer.
- e. Patient compliance – consistent wear of the appliance.
- c) Give four types of retentive components in removal orthodontics. (4 marks)
- d) Outline four types of active components in removal orthodontic appliances. (4 marks)
- e) Enumerate five advantages of removable orthodontic appliances. (5 marks)Model answer
- Convenience – can be removed for eating, brushing and cleaning.
- Reduced plaque accumulation – easier oral hygiene compared to fixed appliances.
- Cost‑effective – generally cheaper to produce and replace.
- Patient compliance – patients can control wear time, improving treatment adherence.
- Versatility – suitable for a wide range of malocclusions and age groups.
- f) Give five requirements for an ideal clasp for use in orthodontic appliances. (5 marks)
- g) Outline five modifications of the Adam's clasp. (5 marks)
Section B ANSWER ANY TWO QUESTIONS
2. Describe the procedure of trimming a mandibular and a maxillary orthodontic models. (20 marks)
3. After receiving impressions, describe the procedure of fabricating an orthodontic appliance with Adam's clasps and a labial bow. (20 marks)
Model answer
- Impression taking – obtain accurate maxillary and mandibular impressions.
- Model pouring – cast the impressions in dental stone.
- Model trimming – prepare the models as per standard protocol.
- Clasp fabrication – design and fabricate Adam’s clasps on the prepared models.
- Labial bow placement – bend and position the labial bow on the maxillary model.
- Assembly – attach the clasps and labial bow to the appliance framework.
- Trial fit – check the appliance in the patient’s mouth and make adjustments.
4.
- a) Explain disadvantages of orthodontic appliances. (10 marks)Model answer
- Limited retention – removable appliances may not hold as firmly as fixed ones.
- Patient compliance required – success depends on patient’s willingness to wear.
- Esthetic concerns – visible appliances can affect appearance.
- Potential for irritation – can cause soft tissue soreness if not fitted properly.
- Reduced force control – less precise force application compared to fixed brackets.
- b) Compare functional and fixed orthodontic appliances. (10 marks)Model answer
- Functional appliances – designed to modify jaw growth and function; removable or fixed.
- Fixed appliances – brackets bonded to teeth; continuous force application.
- Retention – functional often rely on patient compliance; fixed provide constant retention.
- Treatment duration – functional may take longer; fixed often faster for alignment.
- Esthetics – functional can be less visible; fixed may be more noticeable.
- Cost – functional generally cheaper; fixed can be more expensive.
- Maintenance – functional requires regular cleaning; fixed needs professional adjustments.
- Patient suitability – functional for growth modification; fixed for complex malocclusions.