## **Core Concept**
The Broadbent-Bolton cephalometer is a significant tool in orthodontics and oral surgery, used for analyzing the dimensions and relationships of the skull, particularly in the context of facial growth and development. It was designed to provide a standardized method for taking and analyzing lateral cephalometric radiographs. This device plays a crucial role in diagnosis, treatment planning, and research in orthodontics.

## **Why the Correct Answer is Right**
The Broadbent-Bolton cephalometer was indeed devised in **1931**. This invention was pivotal because it introduced a systematic approach to cephalometric analysis, allowing for more accurate assessments of craniofacial morphology. The device ensured that radiographs were taken with the head in a standardized position, which enabled reliable comparisons over time and between individuals. This innovation significantly advanced the field of orthodontics by providing a more scientific basis for treatment planning.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 1911 - This is too early for the Broadbent-Bolton cephalometer, as significant advancements in radiography and orthodontic diagnostics occurred in the following decades.
- **Option B:** 1921 - Still a decade before the actual invention, this period was crucial for the development of radiographic techniques but not yet for the specific cephalometric analysis tool in question.
- **Option D:** 1941 - This is a decade after the invention and does not accurately reflect the introduction of the Broadbent-Bolton cephalometer.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the Broadbent-Bolton cephalometer was a landmark invention in **1931** by Broadbent, which revolutionized the field of orthodontics by introducing standardized cephalometric analysis. This tool has since become a cornerstone in orthodontic diagnosis and treatment planning.

## **Correct Answer:** C. 1931.