Pocket-Dentist

Benchmarking Compact Vision-Language Models
for Dental Image Understanding

Kai Bian*1, Xucheng Guo*2, Yiran Shen2, Ting Dang3, Hong Jia†1
1The University of Auckland   2Shandong University   3The University of Melbourne
*Equal Contribution   Corresponding Author
6,000+
Patients
71,000+
Images
14
VLMs Evaluated
7
Dental Datasets
6.67s
On-Device Latency

Abstract

Dental image understanding is emerging as an important application area for VLMs, but current evaluation remains fragmented across modality-specific datasets, isolated task definitions, and metrics that rarely account for deployment constraints. As a result, it remains unclear whether VLMs can provide reliable dental image understanding across heterogeneous modalities and tasks while remaining practical for resource-constrained deployment. We present Pocket-Dentist, a large-scale multimodal benchmark and deployment pipeline for dental VLMs. We curate and standardize seven dental datasets into a unified vision–language benchmark comprising more than 6,000 patients, 71,000 images, four imaging modalities, six task types, and 14 evaluation metrics. On this benchmark, we evaluate 14 VLMs under zero-shot, few-shot, and LoRA fine-tuning settings, including 12 open-weight models under a uniform LoRA adaptation budget. The results show that zero-shot and few-shot performance is fragmented across modalities and tasks, whereas dental-domain LoRA adaptation enables compact VLMs to become competitive with substantially larger models. In particular, Qwen3-VL-4B achieves the strongest overall performance among compact models and matches or outperforms larger open-weight models (7B–32B) on most primary task metrics. We further deploy a LoRA-tuned Qwen3-VL-4B (Pocket-Dentist-4B) on a commodity smartphone, achieving 6.67s per-sample inference while keeping all computation local to the device.

Benchmark Overview

Pocket-Dentist Benchmark Overview

Figure 1: Overview of the Pocket-Dentist benchmark datasets and task formulations.

Evaluation Pipeline

Pocket-Dentist Pipeline

Figure 2: Deploy-aware evaluation pipeline of Pocket-Dentist.

Zero-Shot Benchmark Results

Bold blue = best in tier. ↑ higher is better; MAE ↓ lower is better.

Tier Model BRAR Acc↑ BRAR F1↑ DR F1w↑ Meta VQA↑ Meta Cap↑ Meta Cls↑ Aariz VQA↑ Aariz CVM↑ COde Cls↑ DenPAR Arch↑ DenPAR Site↑ DenPAR MAE↓ Caries Det↑ Caries Cls↑
Large VLMs
(≥7B)
Lingshu-32B 0.49 0.39 0.60 0.63 0.18 0.34 0.26 0.13 0.48 0.59 0.53 0.88 0.56 0.16
MedMO-8B-Next 0.26 0.19 0.53 0.49 0.09 0.08 0.21 0.05 0.26 0.61 0.29 2.90 0.59 0.84
Qwen2.5-VL-7B 0.27 0.17 0.32 0.45 0.15 0.23 0.20 0.00 0.50 0.40 0.35 1.01 0.63 0.14
gemini-2.0-flash 0.57 0.37 0.00 0.63 0.18 0.36 0.29 0.25 0.54 0.84 0.45 0.42 0.50 0.12
gemini-2.5-flash 0.27 0.26 0.62 0.66 0.14 0.24 0.23 0.12 0.58 0.99 0.51 0.47 0.54 0.13
Compact VLMs
(≤4B)
Qwen3.5-4B 0.17 0.10 0.54 0.82 0.10 0.16 0.17 0.04 0.11 0.40 0.19 3.02 0.49 0.18
Qwen3-VL-4B 0.44 0.37 0.24 0.58 0.20 0.22 0.23 0.08 0.54 0.44 0.23 0.42 0.63 0.58
gemma-4-E4B-it 0.56 0.24 0.61 0.59 0.18 0.31 0.31 0.04 0.51 0.40 0.51 0.52 0.43 0.30
medgemma-4b-it 0.44 0.33 0.57 0.54 0.14 0.16 0.40 0.03 0.27 0.40 0.23 0.89 0.52 0.11
paligemma2-3b 0.10 0.06 0.00 0.00 0.00 0.00 0.20 0.03 0.00 0.00 0.18 0.89 0.64 0.00
SmolVLM2-2.2B 0.56 0.35 0.56 0.00 0.10 0.15 0.23 0.05 0.10 0.60 0.10 0.89 0.44 0.92
InternVL3.5-2B 0.50 0.27 0.09 0.15 0.00 0.00 0.37 0.00 0.14 0.40 0.22 3.21 0.36 0.12
gemma-4-E2B-it 0.56 0.24 0.24 0.48 0.15 0.25 0.39 0.03 0.50 0.27 0.23 0.73 0.61 0.11
InternVL3.5-1B 0.26 0.14 0.62 0.34 0.00 0.00 0.21 0.07 0.14 0.28 0.19 2.27 0.61 0.11

On-Device Deployment

LoRA-tuned VLMs deployed on iPhone 17 Pro (A19 Pro, 12 GB) via Metal-accelerated inference. 100% local.

Model Latency (s) ↓ TTFT (s) ↓ OTPS (t/s) ↑ RAM (GB) ↓
Pocket-Dentist-4B 6.67 1.22 17.07 4.09
InternVL3.5-2B 4.74 0.78 29.47 2.62
Qwen2.5-VL-7B 24.06 2.29 9.60 6.22
Pocket-Dentist-4B achieves a 3.6× latency reduction vs. the 7B baseline while maintaining competitive accuracy.
Pocket-Dentist iOS app

Key Findings

  • 🔍 Zero-shot fragmentation — No single model dominates across all dental tasks.
  • 📈 LoRA adaptation closes the gap — Compact VLMs become competitive with larger models.
  • 🏆 Qwen3-VL-4B is the strongest compact model — Matches or outperforms 7B–32B models after LoRA.
  • 📱 Pocket-Dentist-4B runs locally — 6.67s latency, 4.09 GB RAM, 100% offline on iPhone 17 Pro.
  • 🏥 Medical pre-training ≠ dental performance — Dental-domain LoRA is more effective.