Kure City Pediatric Orthodontic Data Revealed: 'Underbite (Class III Malocclusion)' Accounts for 41.7%, Surpassing National Average. Uehara Dental Clinic Analyzes Regional Traits and Importance of Early Treatment.

Uehara Dental Clinic Kure General and Orthodontic Dentistry (Medical Corporation United, Director: Ryo Uehara), a community-based dental provider in Kure City, Hiroshima Prefecture, has independently compiled data on malocclusion classifications and treatment device adoption (NeoCap Bimler, Invisalign First) for 201 pediatric patients (all under 12 years old) who began orthodontic treatment at our clinic between January 2021 and May 2026.

This survey was conducted to verify a hypothesis formed through daily clinical practice: "Are children in Kure City relatively more likely to have an underbite (Class III malocclusion), where the lower front teeth protrude beyond the upper front teeth?" The goal is to raise local awareness about children's dental alignment, particularly the importance of early treatment.

Survey Results: Pediatric Orthodontic Data at Uehara Dental Clinic (January 2021 – May 2026)

The treatment (contract) outcomes by malocclusion classification for patients under 12 years old at our clinic are as follows:

【Total Number of Cases by Malocclusion Classification】

· Class III Malocclusion (Underbite, Mandibular Prognathism): 84 cases (41.8% of total)

· Class II Malocclusion (Overjet, Maxillary Prognathism): 59 cases (29.4% of total)

· Class I Malocclusion (Crowding, Irregular Alignment): 58 cases (28.8% of total)

※ Total: 201 cases

【Treatment Breakdown by Device (Annual Detailed Data)】

Our clinic offers optimal treatment plans combining "NeoCap Bimler (palatal orthodontics)" and "Invisalign First (clear aligner orthodontics)" tailored to each child’s condition.

Malocclusion

Classification and Treatment Method

2021

2022

2023

2024

2025

2026

Until May

Total by Device

Class I:

NeoCap Bimler

8

15

3

5

5

0

36

Class I:

Invisalign First

2

6

6

4

3

1

22

Class II:

NeoCap Bimler

9

5

8

10

4

2

38

Class II:

Invisalign First

2

5

5

3

4

2

21

Class III:

NeoCap Bimler

12

16

13

10

6

3

60

Class III:

Invisalign First

3

4

3

4

6

4

24

Analysis: The Hypothesis of "More Children in Kure Have Underbites (Class III)" and Regional Trends

Generally, among Japanese people, the most common malocclusion is Class I (crowding, irregular alignment), followed by Class II (overjet), and then Class III (underbite) (based on the Ministry of Health, Labour and Welfare’s Survey on Dental Diseases)

※ Source: Ministry of Health, Labour and Welfare, 23rd Survey on Dental Diseases

https://www.mhlw.go.jp/toukei/list/dl/62-23-02.pdf

However, aggregating our clinic’s five-year data revealed a significant reversal of national trends: Class III (underbite) accounted for over 40% (41.8%) of cases, making it the most prevalent. Two key factors are considered behind this:

Skeletal Regional Characteristics (Genetic Background)

Underbite (Class III malocclusion) is strongly influenced by skeletal genetic factors, such as vigorous lower jaw growth. It is speculated that this skeletal trait has been inherited across generations within the Kure City community.

Recent dental genomics research in Japan (※) has scientifically demonstrated that East Asians, including Japanese people, possess specific genetic traits (e.g., growth hormone receptor gene) related to jaw development, making them skeletally predisposed to a more developed lower jaw and thus a higher potential for underbite (mandibular prognathism) compared to Western populations. The fact that Class III malocclusion is most prevalent in Kure City suggests that these inherent Japanese genetic factors have been strongly preserved as a skeletal characteristic within the local community.

(※ Example note: Findings from research reports such as the Grant-in-Aid for Scientific Research on "Exploration of Susceptibility Genes for Mandibular Prognathism" by Showa University and Kanagawa Dental University)

Additionally, internationally recognized and textbook-level evidence classifies skeletal Class III malocclusion as a typical case where genetic predisposition plays a stronger role than environmental factors (habits, etc.). A famous historical example is the underbite (Habsburg jaw) seen in the European Habsburg royal family, which was inherited across generations.

Parents’ Awareness and High Priority on Early Treatment

Compared to overjet or irregular alignment, underbite (dish-face, protruding chin) directly affects facial appearance (e.g., E-line profile), making it easier for parents to notice changes at an early stage. Furthermore, this reflects the high level of awareness established among Kure City parents through our clinic’s long-standing pediatric orthodontic education initiatives—the belief that "underbite should be treated early."

Uehara Dental Clinic’s Two Pediatric Orthodontic Approaches

For children’s malocclusions, including underbite (Class III), our clinic has introduced two systems that utilize natural growth and development to ensure a healthy future with minimal discomfort.

① NeoCap Bimler Orthodontics (134 cases over 5 years)

A non-removable base called "NeoCap" is attached to the teeth, and the "Bimler" device is worn only during nighttime sleep. It promotes natural jaw growth and creates a foundation for aligning teeth neatly without extractions. In this survey, it was the most selected treatment method, particularly for Class III (underbite) cases, with 60 cases—proving its reliability and track record.

② Invisalign First (67 cases over 5 years)

A transparent, removable clear aligner system designed for children. It is discreet, allowing normal eating and easier brushing at school, reducing the risk of cavities. Demand for this treatment has been rapidly increasing in Kure City in recent years.

Director’s Message: "Consultation at the Right Time—Ages 7 to 9—Creates a Brighter Smile for the Future"

Many parents wonder, "When should I start orthodontic treatment for my child’s teeth?" Especially for underbite (Class III), a child’s jaw growth speed is deeply involved, so initiating treatment during the appropriate window—ages 7 to 9, when front teeth are changing—is the key to avoiding future tooth extractions or major surgical procedures.

"We want the smiles of Kure City’s children to be even more beautiful and healthier."

Based on this data, we will continue to support our local community by offering each child the optimal timing and method of treatment. If you have even a slight concern—"Could this be an underbite?"—please consult us before it’s too late.

★ Free orthodontic consultations are also available via LINE.

https://page.line.me/mpu8918p?openQrModal=true

【About Medical Corporation United Uehara Dental Clinic Kure General and Orthodontic Dentistry】

Clinic Name: Uehara Dental Clinic Kure General and Orthodontic Dentistry (Medical Corporation)

Director: Ryo Uehara

Address: 2-4-8 Yakeyama Central, Kure City, Hiroshima Prefecture

Access: 2-4-8 Yakeyama Central, Kure City, Hiroshima 737-0935

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