Indications, clinical and laboratory stages of manufacturing solid-cast dental bridges.

1. Indications, clinical and laboratory stages of manufacturing solid-cast dental bridges.

2. Bridge prostheses. •   Bridge prostheses are most common category of prostheses in partial included defects of the dentitions. •      The dental arch consists of two symmetrical halves and in loss of one of them another one can take its function. It is considered that the periodontium of each tooth, because of the special reserve possibilities, is capable of maintaining dual masticatory load. The construction of any bridge-shaped prosthesis is based on this principle, when two and more crowns bear intermediate part, body on themselves, which compensates the defect of the absent tooth or teeth. When the tooth load, i.e., width of the intermediate part is more than the reserve possibilities of the periodontium of the teeth, on which abutment crowns are located, it will give arise to physiological irritation, the injury, which will lead to the teeth loosening.

3.   All bridge prostheses can be divided regarding the material into: plastic, metallic, combined. Metallic and combined dentures are also divided into: soldered (at first supporting crowns are made, then the intermediate part, later on all elements are soldered by the solder) and whole cast (at first all parts of the prosthesis are made of wax, and then wax is substituted by the metal by the method of precision casting). The soldered bridge prostheses become the thing of the past, preserving the major advantages - cheapness, easiness of construction, abrading of insignificant quantity of hard tissues of the teeth. The whole cast prostheses with the wide acceptance of precision casting and its significant development acquire greater popularity in dentists and dental technicians. • The following postulate is the more generalized formulation of indications to the bridge prosthesis: the partial defects of the dentition when the sum of the coefficients of the masticatory effectiveness of supporting teeth according to Agapov is more or equal to the sum of the coefficients of the masticatory effectiveness of the absent teeth.

4. Coefficients of masticatory effectiveness according to Agapov: • Teeth       1   2   3   4   5   6   7Total • the upper • jaw 2   1   3   4   4   6   525un. • the lower 2   1  3   4   4   6   5 • Jaw 25 un.

5. Kennedy's classification • 1 bilateral end defect of the dentition. • 2 unilateral end defect of the dentition. • 3 intermediate defect in the lateral parts of the dentition. • 4 intermediate defect in the region of the anterior part.

7. CLASSIFICATION BY V.I.KULAZHENKO • I class.The defect of the dentition is limited by one tooth - the continuous shortened dentition without the distal support (according to Kennedy - II class). • II class. Two defects, limited by two teeth - the shortened dentition with the bilateral defects without the distal support (according to Kennedy - I class). • III class.Two defects, limited by three teeth – bilateral defects, limited by three teeth, one defect without the distal support (on Kennedy - II class, I sub-class). • IV class.Two defects, limited by four teeth – bilateral defects with the distal supports (by Kennedy - III class, I subclass).

8. Indications for prosthetic bridges • Loss of one to four cutters • Loss of a canine • The loss of a premolar or some premolars • The loss of a two premolars and one molar • Permissible by loss on one side of the jaw of the two premolars, first and second molars when preserving and well-developed third molar • By correspondence in calculations of the coefficients of teeth chewing efficiency after N. I. Agapov, I. M. Oxman, V. K. Curlyandskiy.

9. Contraindications for prosthetic bridges • The presence of a rudimentary third molar • Lack of a canine, premolars and first molar • Periodontal disease • Low clinical crowns of teeth

10. EVALUATION OF THE WHOLE CAST PROSTHESES • - Construction of the wax reproduction of the component (wax pattern); • - Installation of sprues and creation of the casting block; • - Preparation of the mixture, utilized for formation of the covering layer of model; • - Coating of the wax reproduction of the component with a covering mass; • - Construction of the casting form; • - Melting of wax from the casting form with the subsequent drying and burning of the casting form; • - Melting of the dental alloy with the subsequent filling of the molten metal in the casting form; • - Cooling of the casting with its subsequent release from the molding mass and sprues; • - If necessary thermal processing of the cast components; • - Polishing, fitting, etc

11. Clinical stages of making solid-cast bridge prostheses include: • Preparation of the abutment teeth with preliminary retraction. • Getting the primary and secondary impressions. • Determination or fixation of occlusion. • Fitting the frame of bridge prosthesis. • Fixing bridge prosthesis.

12. Examination of the patient. Previous preparation of oral cavity for prosthesis

13. Treatment plan. Preparation of teeth.

14. Getting of double and auxiliary impressions.

15. Fixation of central occlusion.

16. Receiving combined model.

17. Modeling of solid-cast framework from wax

19. Casting and finishing of metal framework.