Ideal ridge forms using hydroxylapatite

Abstract

This clinic will present a system of diagnostic and management procedures with a view to obtaining ideal ridge forms in a predictable manner using hydroxylapatite. Success of this system is based on a thorough understanding of the changes that the basal-alveolar bone complex undergoes after dental extraction and denture wear and on a definition of objectives for functional denture design. Anatomy of the residual ridge Pathophysiology of ridge resorption (2 phenomena): Disuse atrophy: confined to ridge remodelling Pressure-resorption (unconfined): Basic mechanical factors related to others: sex, morphogenetic (quantity) and metabolic (quality) factors: osteoporosis Anatomical changes Bone changes: General: From Group I (post extraction) to II (convex), III (flat), IV (concave). Specific: Patterns of resorption along resorptive and depository zones (Enlow). Limits of basal bone. Mandible: Loss of anterior bone contour. Posterior dishing. Paralingual crest. Maxilla: Persistence of anterior slope. Reduction in width. Atypical: “Combination syndrome”. Intermaxillary changes: Posterior crossbite. Anterior pseudoprognathism Soft Tissue changes: Crestal scar band. Muscular attachments. Distribution of keratinized mucosa Facial support Clinical importance of anatomical changes on denture wear and design. Available solutions. Ridge reconstruction with hydroxylapatite Advantages over other solutions (implants): Bone preservation: No bone loss. Building over existing bone (onlay concept) Correction of deficient ridge forms and adverse inter-ridge relationships in all three planes: From narrow convex, flat or concave to broad convex ridge From crossbite to overjet. From class 2 or 3 to 1 Isolation from oral microbiotics Problems with HA (l-2-3 technic-related) Inadequate ridge form: Excessive quantity. Material dispersion and mobility. Submucosal extrusion. Incorrect placement. Posterior buccal instead of lingual. Anterior crossbite uncorrected. Neurosensory Material resorption. Need for more research. Choice of material: Particulate form: Porous or dense Soft block form with collagen. (Alveoform) Indications HA with autogenous bone. Other materials. Ideal Ridge forms Mandible: Comma-shaped, covered with keratinized tissue (skin) with lingual undercuts and fixed vestibular outline (matrix angle line). Maxilla: Inverted U-shaped covered with keratinized palatal mucosa. Technical aspects Mandible: Stage 1: Lingual and subperiosteal approach-Use of hard and soft tissues containing matrices. No splint: Reasons. HA placement: Anterior: Lingual/buccal. (cephalogram) Posterior: Lingual only Stage 2: Total lowering floor with vestibuloplasty and skin graft Maxilla: One-stage augmentation and submucous vestibuloplasty. Splint. Review of complications and specific cases