Lecture Notes: Enlow's V Principle and Counterpart Principle

Enlow's V Principle

Overview

• Concepts proposed by Enlow, under growth and development in Orthodontics.
• Craniofacial bones commonly follow a V shape configuration.
• Bone Deposition: Inner aspect (endosteal surface).
• Bone Resorption: Outer aspect (periosteal surface).

Bone Surfaces

• Endosteal Surface: Lined by osteoblasts (bone-forming cells).
• Periosteal Surface: Lined by osteoclasts (bone-resorbing cells).

Implant Study Evidence

• Implants placed on periosteal and endosteal surfaces.
• Periosteal Surface: Bone resorption and implant detachment observed.
• Endosteal Surface: Bone deposition and no complete implant detachment.

Bone Growth

• Continuous deposition and resorption move bone from a narrow V position to a wider V position.

Examples Demonstrating Enlow's V Principle

Palate

• V-shaped deposition on the palatal side, resorption on the nasal side.
• Leads to descent of the palate.

Mandible

• Growth in posterior and lateral directions.
• Condyle grows upward and backward, causing mandible displacement downward.
• Continuous inner bone deposition and outer resorption.

Enlow's Counterpart Principle

Overview

• Proposes that growth of facial/cranial bones is interrelated with their structural counterparts.
• Aims to maintain balance and functional equilibrium.
• This principle is not widely accepted.

Examples of Counterpart Relationships

• Nasomaxillary complex and anterior cranial fossa.
• Width of ramus and maxillary/mandibular arches.
• Maxillary tuberosity and lingual tuberosity.

Summary

• Enlow's V Principle: Most accepted for craniofacial bone growth.
• Enlow's Counterpart Principle: Less accepted, suggests interrelated growth for balance and equilibrium.