Rationale ● Advantages ● Disadvantages ● Indication and contraindication

A removable partial denture or complete that covers and rests on one or more remaining natural teeth roots and/or dental implants

Root Retaining ….. Why??? (Rationale of Overdentur)

Functional and biological Preservation of sensory input from the periodontal receptors the masticatory performance Preservation of Alveolar bone

● Refers to information provided about the position and movements of the body and its parts by receptors

● A sensory nerve terminal that respond to stimuli of various kinds

● Those receptors located in the muscles, tendons, ligaments, joints, and periodontal ligaments which give input regarding movement and position

The periodontal ligament is richly innervated by proprioceptors

The neuromuscular function of the masticatory system depends on the integration of sensory feedback and motor neuron response

The function of the masticatory system (motor responses) is dependent on the sensory input of various components, such as periodontal ligaments, salivary glands, the epithelial surface of oral cavity, muscles, and TMJ

Preservation of one of the major sensory input in the oral cavity

1.The sensory input from periodontal receptors is more precise than that of the oral mucosa 2.Natural anterior teeth exhibit more sensitivity and discrimination (load detection #1 gm) than the posterior teeth (load detection #8-10 gm)

3) The dimensional perception (discrimination of different thickness of objects) is more in patients with natural teeth than edentulous patients 4) The receptors in the periodontal ligament were directionally sensitive

5. The canines are the most sensitive of all oral structures (it had more neurons than all teeth) 6. Vital and devitalized teeth equal sensory input

7. Periodontal receptors indirectly regulate the range and the type of masticatory strokes determined muscle activity controlled parotid secretion

8. Perception of teeth with reduced alveolar support almost that same as with those with normal bone support 9. Generalized decrease in sensory capacity including oral cavity as age increased Use of overdenture is an attempt to retain every possible sensory element

Overdentur patient had chewing efficiency one-third higher than complete-denture patients

Tooth mobility will reduce 60% if the teeth reduced in vertical height up to the gingival level

Overdenture patients could discriminate measured occlusal forces better at the higher levels than patients with conventional denture.

● The use of overdenture preserved the alveolar bone in both height and width because the protective effect of the PDL receptors With excessive load Send signals to the muscles which will decreases the contractions

● Stability ● Patients acceptance ● Retention ● Decrease trauma to ● Esthetic supporting tissues ● Reasonable cost ● Preservation of ● Simplicity and familiarity existing structures of construction ● Minimal adjustment ● Maintenance ● Transitional or training ● Equally effective or superior denture method of treatment ● Reversibility ● Using of attachments ● Conversion to complete denture ● Ease in cleaning ● Possibility of roofless denture ● Ease in VD measurements ● Occlusion

1.Cost 2.Bulkness 3.It is removable 4.Possibility of caries and periodontal diseases

1.Presence of few remaining teeth 2.Poor prognosis for complete denture 3.When pronounced vertical overlap of anterior teeth is required 4.When the remaining teeth were of questionable value as conventional abutments

1.Patient refuse this type of treatment 2.Patient can not maintain good oral hygiene 3.When another method promises to give superior results than overdenture