Jean-Daniel Orthlieb
Prof Em, DDS, MSc, PhD
Aix-Marseille University, Marseille, France
FRANCE
Session 23 · DAY 2 (Nov. 6, 2026) · 16:00–16:30 CET
The Forgotten Curve of Spee: Why Does It Matter?
Abstract
The curve of Spee is a fundamental feature of human occlusal architecture, yet it is frequently overlooked in contemporary dentistry. Orthodontic treatments and prosthetic reconstructions often tend to flatten the occlusal architecture, raising a simple question: why does the curve of Spee exist, and does it really matter?
The curve of Spee is not an arbitrary dental arrangement. Its geometry is closely related to mandibular morphology and therefore varies among individuals. Understanding these anatomical relationships provides a rationale for individualized occlusal design rather than systematically adopting a flat or standardized occlusal plane.
Restoring an appropriate curve of Spee may contribute to occlusal stability and functional efficiency by providing a posterior tooth arrangement consistent with mandibular anatomy and functional guidance.
The challenge is therefore not only to recognize the importance of the curve, but also to determine and reproduce it clinically. Individualized morphometric parameters can be used to estimate its radius. SPEE-Doc, a simple, free digital calculation tool, facilitates this process and provides a patient-specific reference for occlusal reconstruction from a simple photograph. The calculated curve can then be transferred to the digital workflow using a virtual template to guide posterior tooth positioning.
This presentation proposes a practical journey from anatomy to digital reconstruction. Restoring an individualized curve of Spee promotes treatment stability and functional efficiency without making treatment more complex. It is primarily a matter of knowledge: understanding the curve makes it simple to reproduce.
Learning Objectives
- Understand the anatomical basis of the curve of Spee and its relationship to individual mandibular morphology.
- Recognize the role of the curve of Spee in occlusal stability and functional efficiency.
- Apply the SPEE-Doc digital tool to calculate and clinically transfer an individualized curve of Spee, using a virtual template within the digital workflow.
Biography
Prof. Jean-Daniel Orthlieb received his DDS degree from Aix-Marseille University, France, in 1978. He obtained postgraduate qualifications in Anthropology in 1979 and in Fixed Prosthodontics and Occlusodontology in 1980, followed by a PhD in 1990.
He became Associate Professor at Aix-Marseille University in 1993 and Full Professor in 2007. He retired from the University in September 2021.
His main fields of expertise are comparative anatomy, occlusion, temporomandibular disorders (TMDs), and prosthodontics. He has authored or co-authored 8 books and more than 170 scientific publications in these fields.