The　development　of　an　accurate　and　robust　positioning　system　for　oral　and　maxillofacial　surgery　(OMS)　is　a　challenging　task,　primarily　due　to　the　oral　space　limitations　and　line-of-sight　occlusions.　This　paper　presents　a　novel　lightweight　integrated　positioning　system　for　OMS,　which　can　provide　practical　guidance　utilizing　only　a　micro　camera　installed　on　the　end　of　the　surgical　instrument.　An　efficient　region-based　pose　tracking　method　for　texture-less　teeth　is　proposed,　which　can　use　search　lines　around　the　object　contour　and　simple　local　region　partitioning　strategy　to　improve　pose　accuracy.　Besides,　to　deal　with　the　possible　partial　occlusions　of　target　during　surgery,　an　occlusion-aware　weight　function　is　presented　and　utilized　seamlessly　in　the　pose　optimization　pipeline.　This　function　calculates　the　pixel-wise　occlusion　probability　using　object　contour　and　distance　constraint,　helping　to　improve　the　tracking　robustness.　Pivot　calibration　evaluation　reveals　that　the　tracking　accuracy　of　the　proposed　camera-based　handpiece　is　higher　than　the　marker-based　handpieces.　Comparative　experiments　demonstrate　that　proposed　pose　tracking　method　has　higher　accuracy　than　existing　state-of-the-art　methods　and　ablation　study　confirms　the　effectiveness　of　the　occlusion　handling　strategy.　The　overall　positioning　experiment　indicates　that　the　proposed　system　has　satisfactory　static　poses　stability　and　positioning　accuracy.　Furthermore,　the　main　advantage　of　our　system　is　that　it　is　lighter　and　more　integrated　than　other　systems,　which　can　reduce　the　system　complexity,　decrease　the　risk　of　line-of-sight　occlusion,　and　lower　the　surgery　cost.