You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["AnatomicalEntity"].

Please return the output as a JSON object of the format: {"AnatomicalEntity": ["tumor cells", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Cigarette smoking and alveolar bone height in subjects with a high standard of oral hygiene.
Smokers and non-smokers were compared with respect to alveolar bone height. The study covered 235 subjects aged 21-60 years, 72 of whom were smokers. Oral hygiene status and dental care habits were above average and of equal standard in both groups (PlI = 0.9). Alveolar bone height was assessed on radiographs and expressed as % of the root length. Alveolar bone height was significantly reduced in smokers as compared to non-smokers, the mean +/- SEM being 77.9 +/- 1.3% and 82.8 +/- 0.6%, respectively (P less than 0.001). Regression analysis suggested that periodontal breakdown judged from loss of alveolar bone over time was more accelerated in smokers than non-smokers. The lower bone height in smokers remained when age and oral hygiene were allowed for. It is concluded that smoking is a risk factor for periodontal health.
{"AnatomicalEntity": ["Alveolar bone", "dental", "periodontal", "Oral", "alveolar bone", "lower bone", "oral", "root"]}