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Maxillofacial Trauma
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
Avulsed teeth may also be displaced into the soft tissues, particularly of the lip and lip lacerations should be carefully explored before closure in the presence of missing or broken front teeth. A fracture of the crown of a tooth may expose the tooth pulp which can be extremely painful and is frequently the main complaint of a patient with a facial injury.
Stainless Steel Crowns for Primary Molars
Published in M S Duggal, M E J Curzon, S A Fayle, K J Toumba, A J Robertson, Restorative Techniques in Paediatric Dentistry, 2021
M S Duggal, M E J Curzon, S A Fayle, K J Toumba, A J Robertson
Recent research has shown that stainless steel crown restoration of primary molars is superior to that achieved with amalgam, composite resin or glass ionomer cement. Once fitted, the crowns seldom need replacing. Our own research has shown that five years after placement over 80% of stainless steel crowns are still in place (Figure 1.9).
Impacted Maxillary Canines: A Review
Published in Niall MH McLeod, Peter A Brennan, 50 Landmark Papers every Oral & Maxillofacial Surgeon Should Know, 2020
Alice Cameron, Serryth Colbert
Natural eruption may follow surgical exposure, or auxiliary attachments can apply orthodontic force. Different forms of orthodontic traction may be applied including fixed and removable appliances. Only enough bone should be removed to enable visualisation of the crown, as increased bone removal is noted to reduce later alveolar bone support. The auxiliary attachment may be placed immediately or following placement of a healing dressing, with the latter suggested to allow more favourable placement of the attachment and vector control. Apically repositioned flaps are recommended for labially placed canines to ensure there is keratinised mucosa at the cementoenamel junction to optimise periodontal health and minimise recession.
Periapical status transitions in teeth with posts versus without posts: a retrospective longitudinal radiographic study
Published in Acta Odontologica Scandinavica, 2022
Marika Koutsouri Haereid, Lina Stangvaltaite-Mouhat, Vibeke Ansteinsson, Ibrahimu Mdala, Dag Ørstavik
Teeth restored with crowns or fixed dental prostheses constituted the ‘Endo-crown’ group. All crowns and fixed dental prostheses included in this study were metal ceramic crowns made of cast gold alloys. The final impression material was polyether (Permadyne, Impregum Penta; 3M) combined with retraction cord. The entrance of the root canals was usually covered with IRM (Intermediate Restorative Material; Dentsply) and the cavity was filled with composite or glass-ionomer cement. Temporary restorations used were made in dimethylmethacrylate (Luxatemp Automix; DMG) or bismethylene-bismethacrylate (Protemp; Espe) using prefabricated celluloid, polycarbonate crown forms or alginate impressions taken before preparation procedures. Marginal adaptation of the crowns and fixed partial prostheses was verified both clinically and radiographically before final cementation.
Inner marginal strength of CAD/CAM materials is not affected by machining protocol
Published in Biomaterial Investigations in Dentistry, 2021
Julia Lubauer, Renan Belli, Fernanda H. Schünemann, Ragai E. Matta, Manfred Wichmann, Sandro Wartzack, Harald Völkl, Anselm Petschelt, Ulrich Lohbauer
In the present study, the mechanical test method developed in Ref. [15] was employed to assess the inner marginal strength of the evaluated materials. To provide for the standardization of the geometrical shape to be machined, a model crown was designed using CAD software based on a metallic abutment with a specific form of a half-sphere with elongated cylindrical margins (Figure 1(a)) to render a sphero-cylindrical object (Figure 1(b,c)) as a crown-like specimen geometry. This shape differs from a dental crown by having a rotational symmetry around its long axis, a 0.5 mm internal margin radius, and a sharp external angle in 90° degrees. This was intended to allow a uniform loading contact around the internal axial wall just below the internal rounded margin and a homogeneous stress state over the inner margin’s circumference. The thickness of the specimens was set to 1.65 mm so to induce the highest marginal stress in the inner margin, the region where clinical marginal fractures are usually located [3,4]. Thinner margins tend to magnify the stress at the outer margins, where chippings at the 90° angle rim affect the failure mode [15].
Marginal and internal fit of crowns based on additive or subtractive manufacturing
Published in Biomaterial Investigations in Dentistry, 2021
Yasser Haddadi, Bahram Ranjkesh, Flemming Isidor, Golnosh Bahrami
The marginal and internal fit of the crowns were measured before cementation using the replica technique, and after cementation by sectioning the crown and tooth. In order to measure the marginal and internal fit of the crowns before cementation, silicone replicas of the gap between the abutment teeth and the crowns was obtained using the replica technique, as described by Molin and Karlson [19], and Boening et al. [20], Thus, all crowns were fully seated using firm finger pressure, with light-body silicone (Extrude, Kerr) applied internally in the crowns. After setting of the light-bodied material, the internal impression was stabilized with a heavy-body material (Extrude, Kerr) in a different colour. The light-body replica impression was assessed under loupes (2.3× magnification) and if any defects were observed, the impression was retaken. A scalpel (10 A, Swann Morton) was used to section the replicas. Replicas were sectioned in mesiodistal and buccolingual directions, resulting in four cross-sections for each restoration. The span of the cement space corresponding to light-body silicone material thickness was measured at four predetermined locations. Marginal fit was assessed as the marginal gap (MG) as defined by Holmes et al. [21]. The internal fit was assessed at three different points; the axial wall (AW), the cusp tip (CT), and the occlusal surface (OC) on each cross-section (Figure 1), resulting in 16 measurements per replica.