PMC

(A) Tooth width and lamellar frequency in the occlusal surface of the upper jaw (r =  − 0.558, t =  − 7.699, p < 0.05). (B) Tooth width and lamellar frequency in the buccal side of the upper jaw (r =  − 0.476, t =  − 6.201, p < 0.05). (C) Tooth width and enamel thickness (ET) of the upper jaw (r = 0.531, t = 7.179, p < 0.05). (D) Width and lamellar frequency in the occlusal surface of the lower jaw (r =  − 0.649, t =  − 7.915, p < 0.05). (E) Width and lamellar frequency in the buccal side of the lower jaw (r =  − 0.453, t =  − 7.523, p < 0.05). (F) Width and ET of the lower jaw (r = 0.457, t = 4.759, p < 0.05).

(A) Coronal section of the jaw and tooth of a juvenile specimen of P. vitticeps ROM R8510 showing minimal ossification of the jaw bone, and pleurodont tooth attachment; (B) close up of a juvenile specimen’s (ROM R8510) dentition, showing unworn morphology; (C) coronal section of a juvenile specimen (ROM R8234) showing pleurodont implantation, and remodeling; (D) closeup of the attachment site in ROM R8234, showing the labial side of the dentition being resorbed by an osteoclast; (E) coronal section of the coronoid process (ROM R8234) showing a tooth developing lingually inside the coronoid and dentary; (F) a close up of the tooth in the jaw bone, showing the resorption of the jawbone around newly developing tooth. Abbreviations: ab, alveolar bone; ac, acellular cementum; cb, cancellous bone; cp, coronoid process de, dentine; dt, developing tooth; lb, lamellar bone; en, enamel; ost, osteocyte lacunae; oc, osteoclast; rb, resorption bay; rl, reversal line. All un-labeled scale bars = 1 mm.

(A) Coronal section of the jaw and tooth of an adult specimen of P. vitticeps (ROM R8507) showing the maintained vasculature and worn enamel on the labial side, in cross polarized light; (B) Coronal section of ‘A’ in normal transmitted light; (C) Coronal section of the jaw and tooth of an adult specimen of P. vitticeps ROM R8507 showing the extensive remodeling of the tooth attachment site as well as the tooth, in cross polarized light; (D) Coronal section of ‘C’ in normal transmitted light. Abbreviations: de, dentine; lb, lamellar bone; en, enamel; vc, vascular canals; rz, remodeling zone. Scale bar = 500 um.

Alveolar tooth socket thickened due to formation of torus. The torus consists entirely of lamellar bone. At the left side the periodontal ligament space with the tooth surface are shown.

Histological anatomy of the dentary and associated dentition. (A) A cross‐section of ROM77312, TS00303, showing the dentary with associated dentition, tooth is in the 2^nd position; (B) close‐up of the attachment tissues on the labial side of TS00303; (C) the attachment tissues on the lingual side TS00303; (D) a close‐up of the lamellar bone structure of the dentary in TS00303; (E) incomplete ankylosis shown in TS01110, ROM77323; (F) a longitudinal section of the dentary and associated dentition showing plicidentine ROM77317 TS01108; (G) close‐up of plicidentine structure showing canals and infoldings TS01108. ab, alveolar bone; ac, acellular cementum; c, canal; cr, crown; de, dentine; en, enamel; jb, jaw bone; ia, incomplete ankylosis; lb, lamellar bone; rl, reversal line; rt, root.

Representative section of a T2 site after a) 4 weeks (Mc Neal staining of M1 (dog #2, left jaw) where the circle indicates new woven bone formation on the pre-existing alveolar bone and also a thick fibrous tissue band on the outer surface of the newly formed bone; relative bone height recovery for this tooth was 0.71 assessed by µ-CT and 0% new functional periodontal ligament assessed by histologic evaluation), b) 12 weeks (Mc Neal staining of P2 (dog # 7, left jaw) where the square shows a tooth defect covered by a thick layer of acellular cementum and mesenchymal cells as well as lamellar bone filling the tooth defect; the circle indicates good integrated newly formed lamellar bone and the arrow indicates a thick fibrous band crossing between the old and newly formed lamellar alveolar bone; relative bone height recovery for this tooth was 0.75 and the new functional periodontal ligament was assessed as 100%)

Intraoperative and pathological findings of the bilocular lesion in the mandible. (a) Bicameral bone resorption after resection of the bilocular lesion. After total resection of the bilocular lesion and extraction of the 1st premolar, bicameral alveolar bone resorption was observed. (b) The resected bilocular lesion. The left half is the proximal part of the lesion and the right side is the distal part. The proximal part is in bright red and the distal part is in dark red. (c) Pathological findings of the proximal part of the lesion. The components of hard tissue in the proximal part of the lesion represented lamellar structures of cementum (arrowheads). (d) Pathological findings of the distal part of the lesion, which showed severe inflammation without tooth structure components inside.

(a) Sagittal histologic slice of scaffold in continuity with rabbit mandible (b) High magnification from 4a demonstrating porous ingrowth (c) Highly cellular and vascularized woven bone structure, as well as newer, organized lamellar bone formation depicted by arrows. (I=Incisor, T= tooth, IAN= inferior alveolar nerve)

The bone distal to the erupting M₁ in the 13 week pigs consisted mainly of reticular fibrolamellar bone adjacent to the tooth roots in all cervical through apical locations (). The mineralized woven bone matrix formed thin trabeculae interspersed with immature primary osteons with large diameter vascular marrow canals. The primary osteons were oriented obliquely throughout the matrix and the vascular canals anastomosed irregularly, agreeing with the category definition for reticular fibrolamellar bone (). In some samples, the most cervical regions were reticular fibro lamellar bone adjacent to the root but laminar bone more distal from the root. Throughout the length of the tooth root, thin trabeculae projected into the periodontal ligament tissue. The diastema region appeared similar to the bone adjacent to the developing tooth root, including mainly fibrolamellar bone ().

The bone distal to the erupting M₁ in the 13 week pigs consisted mainly of reticular fibrolamellar bone adjacent to the tooth roots in all cervical through apical locations (). The mineralized woven bone matrix formed thin trabeculae interspersed with immature primary osteons with large diameter vascular marrow canals. The primary osteons were oriented obliquely throughout the matrix and the vascular canals anastomosed irregularly, agreeing with the category definition for reticular fibrolamellar bone (). In some samples, the most cervical regions were reticular fibro lamellar bone adjacent to the root but laminar bone more distal from the root. Throughout the length of the tooth root, thin trabeculae projected into the periodontal ligament tissue. The diastema region appeared similar to the bone adjacent to the developing tooth root, including mainly fibrolamellar bone ().

Twenty-four months of evaluation with highly lamellar bone around dentin particles.

Immature bone was observed in some areas with lamellar bone around particles.

Morphological characteristics of Trigonioidacea. (a–d,f) Right valve, (e,g,h) left valve, (a,c,e,g) external view and (b,d,f,h) internal view. Scale bar, 1 cm (adapted from , fig. 1). aa, anterior adductor sca; aarv, angle of anterior revised V-shaped ribs; apc, anterior pseudocardinal(s); apr, anterior pedal retractor scar; aprv, angle of posterior reversed V-shaped ribs; arvr, anterior reversed V-shaped ribs; asmv, angle of submedian V-shaped radial ribs; cgl, commarginal (concentric) growth line; hcr, hinge crenulation; imcr, internal marginal crenulation; pa, posterior adductor scar; pl, pallial line; plt, posterior lamellar tooth (teeth); prvr, posterior reversed V-shaped ribs; rr, radial rib; smvr, submedian V-shaped radial ribs; smt, submedian tooth (teeth).

Histological thin sections showing odontode overgrowth. (a) Representative heterostracan Drepanaspis showing region sampled. (b) Sampled heterostracan Psammolepis sp. dermal armour fragment section. (c) Magnified inset showing multiple odontodes overgrown with acellular bone. (d–f) Glyptolepis sp., skull roof fragment. (f) Magnified inset of (e), multiple odontodes stacked on one another overlain by bone tissue; dentine tubules indicate location of dentine. (g–i) Laccognathus sp., skull roof fragment. (i) Magnified inset of (h), two odontodes overlaying one another with bone tissue in between. (j–l) cf. Cacops, palatine. (k) Oblique section through the palatine shows a fragment of a tooth at the oral surface and at least two generations embedded within lamellar bone. (l) Magnified inset of (k), a palatal tooth fully embedded in lamellar bone showing enamel, dentine, pulp cavity. (m–s) Captorhinus sp., pterygoid. (n–p) Organized lamellar bone overlaying and embedding teeth along the antero-medial edge of the bone; pulp cavity still visible in partially embedded teeth. (q–s) Transverse flange of the pterygoid embedding multiple generations of teeth. The arrows (a–i) point dorsally and (j–s) point orally. Labels are as follows: de, dentine; en, enamel; lb, lamellar bone; pc, pulp cavity; wb, woven bone. Broken line arrows = the direction of the dorsal surface. Solid line arrows = oral surface. Scale bars = 500 µm. Line drawings redrawn from the following sources: psammosteid heterostracan Drepanaspis gemuendenensis []; Glyptolepis []; Laccognathus []; Cacops []; Captorhinus [D. Scott].

a) Low (insets) and high resolution light micrographs of ultrasectioned surface blocks illustrated narrowed PDL-space (arrows) between alveolar bone (AB) and tooth. All micrographs illustrate AB, which is a combination of bundle bone (asterisks) and lamellar bone. Bundle bone is significantly closer to cementum (C). b) Hematoxylin and eosin staining (H&E) of AB coupled with polarized light microscopy demonstrated dominant collagen fibers of different dimension and orientation within bundle bone (mainly radial fibers, straight arrows) compared to lamellar bone (mainly circumferential fibers, curved arrows). It should be noted that both types of bone within AB contain interwoven fabric-like structure.

Mature lamellar bone showing orange red component under polarizing microscope.

Periapical and panoramic radiographs and histopathological microphotographs of our case of idiopathic osteosclerosis (IO). (A) Initial periapical radiograph before the orthodontic treatment revealed an IO lesion between teeth 33 and 34 and impaction of tooth 34. (B) Periapical radiograph taken 2 years after extraction of tooth 35 and orthodontic treatment showed the persistence of the IO lesion, the eruption of tooth 34 to the occlusal level, and a 2-mm space between teeth 33 and 34. (C, D and E) Low-power (C; original magnification, 4×), medium-power (D; original magnification, 10×), and high-power microphotographs (E; original magnification, 20×) demonstrated trabeculae of dense lamellar bone and fibrotic marrow tissues without a chronic inflammatory cell infiltrate. (F) Panoramic radiograph showed the closure of the space between teeth 33 and 34 by orthodontic treatment and the recurrence of the IO lesion 5 months after surgical removal of the lesion. (G and H) Two-year and 8-year follow-up panoramic radiographs showed the persistence of the IO lesion 2 years (G) and 8 years (H) after surgical excision of the IO lesion.

(a) Scanning electron microscopic (SEM) images of natural tooth (upper), the engrafted osseo-integrated implant (middle) and the engrafted bio-hybrid implant (lower) at 30 days post transplantation was performed. Scale bar, 20 μm and 1.0 μm in the lower and higher magnification, respectively. D, dentin; AB, alveolar bone; PDL, periodontal ligament; Imp, implant. (b and c) Transmission electron microscopic (TEM) observation of a natural tooth (left) and the engrafted bio-hybrid implant (right). Formation of lamellar cementum (b, arrowhead) and invasion of Sharpey's fibres into the cementum (c, arrowhead). Scale bar, 500 nm. C, cementum; PDL, periodontal ligament. (d) Amounts of calcium (Ca, red), phosphorus (P, green), and titanium (Ti, blue) in a natural tooth (top), the engrafted osseo-integrated implant (middle) and the engrafted bio-hybrid implant (bottom), as determined by SEM. The amounts of elements were measured in the area between dotted lines. AB, alveolar bone; PDL, periodontal ligament; Imp, implant. (e) Elemental mapping superposition of the natural tooth (top), osseo-integrated implant (middle) and bio-hybrid implant (bottom). Calcium (Ca, red), phosphorus (P, green), titanium (Ti, blue) and merged images are shown. AB, alveolar bone; PDL, periodontal ligament; Imp, implant.

Regular (A) and polarized (B) histological image of the specimen from the dog with an ORNJ lesion of the mandible (Case 3). (A) The alveolar bone comprises primarily lamellar, osteonal bone with limited interstitial woven bone. The bone is necrotic, as evidenced by diffuse, empty osteocyte lacunae, and attached basophilic to eosinophilic biofilm (top of image). Multifocal, irregularly spaced, and shaped resorption bays are present within the alveolar bone (clear spaces/osteoporosis). Tooth dentin and a thin rim of cementum are evident at the bottom of the image. These eosinophilic matrices are more evident in the polarized image (B). A periodontal ligament is absent between the cementum and adjacent alveolar bone, consistent with ankylosis of the tooth.

Representative section of a T1 site after a) 4 weeks (Mc Neal staining of P2 (dog #1, right jaw) where the arrows show new woven bone formation that overgrowths also pre-existing lamellar alveolar bone (cross); relative bone height recovery for this tooth was 0.80 assessed by µ-CT and 35% new functional periodontal ligament (25% tip, 10% cranial) assessed by histologic evaluation (note: old bone is visible, PDL functionality was assessed regarding new bone only)), b) 12 weeks (Picrosirius red staining of M1 (dog # 7, left jaw) which shows good integrated newly formed lamellar bone (arrow) on top of the pre-existing alveolar bone (cross) and the scalloped pattern on the tooth surface due to the bur is good visible; relative bone height recovery for this tooth was 0.94 and the new functional periodontal ligament was assessed as 100%), c) inlet of b) showing functional periodontal ligament (arrows) under polarization light