[A study on alveolar ridge augmentation guided by orthodontic forced eruption in patients with severe periodontitis]

Objective: To evaluate the clinical effect of alveolar bone augmentation in teeth with severe periodontitis using orthodontic forced eruption. Methods: Twelve patients (5 males and 7 females) with severe periodontitis and malocclusion who visited the Department of Orthodontics and Department of Periodontology, Peking University School and Hospital of Stomatology from October 2018 to May 2022 were included in this retrospective study. The age was (38.8±6.6) years (24-49 years). A total of 16 maxillary incisors that could not be retained due to severe periodontitis were included. The orthodontic fixed appliance was used to extrude the teeth. Cone-beam CT (CBCT) images of the patients before and after orthodontic forced eruption were collected. The voxel-based registration was used to superpose the images before and after orthodontic forced eruption. The height, thickness, and apical alveolar bone area were measured on the sagittal plane. The alveolar bone volume before and after orthodontic forced eruption was measured using three-dimensional reconstruction technique, and the influencing factors related to the alveolar volume change were analyzed. Results: The results of this study showed that the eruption distance of the teeth was (2.37±0.82) mm, and the alveolar bone height increased by (1.11±0.79) and (0.98±0.79) mm (t=3.73, P=0.010; t=4.85, P<0.001). The proximal and distal alveolar bone height increased by (1.10±0.78) and (0.86±1.08) mm, respectively (t=5.59, P<0.001; t=3.18, P=0.006). The alveolar bone thickness decreased (0.30±0.31) mm (t=-3.75, P=0.002) and alveolar bone area increased (6.84±5.86) mm2 (t=3.71, P<0.001). The alveolar bone volume increased (53±49) mm3 (t=4.38, P<0.001). The alveolar bone volume was moderately positively correlated with eruption distance, apical and mesial alveolar bone thickness (r=0.55, P=0.028; r=0.63, P=0.008; r=0.67, P=0.005). Conclusions: Orthodontic forced eruption results in a favorable increase of the alveolar bone in the upper incisor that cannot be retained due to severe periodontitis, which provides better periodontal hard tissue conditions for subsequent dental implant.

[Clinical and radiographic effect of simultaneously labial and lingual augmented corticotomy: a prospective case series study]

Objective: To investigate soft-and hard-tissue changes after simultaneously labial and lingual augmented corticotomy in patients with insufficient alveolar bone thickness of lower anterior teeth both in labial and lingual side during orthodontic treatment. Methods: From January 2021 to June 2022, 10 patients [2 males and 8 females, (26.2±3.1) years old] who received orthodontic and orthognathic combined treatment from the Fourth Clinical Division, Peking University School and Hospital of Stomatology were selected. The alveolar bone thickness of lower anterior teeth both in labial and lingual side in these patients was less than 0.5 mm according to cone-beam CT examination before or during treatment, and 60 lower anterior teeth were included. The 10 patients were treated with simultaneously labial and lingual augmented corticotomy. The differences in gingival recession, papilla index and the differences in labial and lingual alveolar bone thickness of lower anterior teeth were compared. Results: Six months after surgery, the alveolar bone thicknesses at the 4 mm under cemento-enamel junction (CEJ), 8 mm under CEJ and at the apical level [labial side: (1.02±0.39), (2.22±0.89) and (4.87±1.35) mm; lingual side: (1.07±0.46), (2.31±1.04) and (3.91±1.29) mm] were significantly higher than that before surgery [labial side: (0.02±0.09), (0.06±0.21) and (2.71±1.33) mm]; lingual side: (0.14±0.29), (0.40±0.52) and (2.13±1.02) mm] (P<0.001), respectively. The increases in alveolar bone thickness of central incisors [apical level on labial side: (2.53±1.20) mm, 8 mm under CEJ on lingual side: (2.27±1.24) mm, apical level on lingual side: (2.66±1.49) mm] and lateral incisors [apical level on labial side: (2.42±1.30) mm, 8 mm under CEJ on lingual side: (2.28±0.92) mm, apical level on lingual side: (1.94±1.15) mm] were significantly higher than that of canines [apical level on labial side: (1.52±1.47) mm, 8 mm under CEJ on lingual side: (1.17±1.09) mm,apical level on lingual side: (0.74±1.37) mm] (P<0.01). There were no significant differences in the degree of gingival recession [labial side before surgery: (0.72±0.88) mm, lingual side before surgery: (0.80±1.09) mm; labial side 6 months after surgery: (0.72±0.81) mm,lingual side 6 months after surgery: (0.89±0.21) mm] and gingival papilla index [before surgery: 1.00(0.75, 2.00); 6 months after surgery: 1.00(1.00, 2.00) ] between pre-operation and 6 months after surgery (P>0.05). No serious complications occurred. Conclusions: The method used in this article for simultaneously labial and lingual augmented corticotomy was safe and feasible. This surgery has positive clinical significance for the stability of the periodontal tissue in orthodontic treatment for patients with alveolar bone thickness less than 0.5 mm of lower anterior teeth both in labial and lingual side.

Conformation change of bovine serum albumin induced by bioactive titanium metals and its effects on cell behaviors

The conformation change of bovine serum albumin (BSA) induced by bioactive titanium surfaces, including acid-alkali-treated titanium (AA-Ti) and alkali-heat-treated titanium (AH-Ti), was studied, and its effects on the activity of MC3T3-E1 cell were evaluated. Pure titanium metal (P-Ti) was used as control. The AA-Ti could adsorb more BSA on its surface than AH-Ti and P-Ti. The α-helix part of the protein adsorbed on P-Ti has weakly decreased compared with native BSA, and it dramatically decreased on AA-Ti and AH-Ti. The β-sheet segment of proteins adsorbed on P-Ti and AH-Ti had obviously increased. Much more tryptophan residues were exposed after the protein conformation changed when it interacted with AH-Ti, and some tryptophan residues were enveloped after it interacted with AA-Ti and P-Ti. AA-Ti has more tryptophan residues enveloped than P-Ti. All titanium surfaces induced tyrosine residues exposed, especially for the P-Ti. The higher ratio of COO(-)/NH3(+) for the proteins on P-Ti and AA-Ti indicated an orientation of proteins on P-Ti and AA-Ti, which makes more COO(-) exposed. The lower ratio of COO(-)/NH3(+) on AH-Ti indicates that more NH3(+) is exposed on its surface. The cell proliferation ability on different treated titanium surfaces coated with BSA followed by the order: P-Ti > AA-Ti > AH-Ti, which indicated that the protein conformation change on different bioactive titanium surfaces has great effect on the cell activity. Our results showed that the different biological response of bioactive titanium metals might depend on the protein conformation change induced by the surface structure.

The chemical properties of silica particle surface in relation to silica-cell interactions

Although silicosis has been studied extensively, the mechanism is still not fully understood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are thought to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free-radical interactions.