Pathology of the Hard Dental Tissues 1st edition by Albert Schuurs 9781118970430 1118970438

Prior to and during the development of the teeth within the jaws

During the eruption of teeth

After the eruption of the teeth

Genetics

Interpretation of family trees

Table 0.1 Autosomal inherited hypocalcified enamel (A)

Table 0.2 Sex-chromosome (X-bound) inherited hypocalcified enamel

Table 0.3 Polygenetic heredity

Section I Developmental Anomalies

1 Anomalies of Number

1.1 Introduction

1.2 Hypodontia

1.2.1 Isolated dental agenesis

Epidemiology

Primary dentition

Permanent dentition

Third molars

Mandibular second premolar

Maxillary lateral incisor

Figure 1.1 Agenetic right permanent maxillary lateral incisor; the contralateral tooth is underdeveloped.

Maxillary second premolar

Mandibular central incisor

Figure 1.2 Agenetic permanent central incisors – the deciduous teeth are retained.

Figure 1.3 Four retained deciduous incisors in the mandible; the permanent successors are agenetic.

Other teeth

Aetiology

Evolution

Table 1.1 Teeth per quadrant of the archetypal permanent dentition, the teeth remaining in modern humans according to Bolk, and present point of view628

Heredity

Figure 1.4 Mother (A) and daughter (B) with agenetic maxillary permanent lateral incisors.

Relationships between teeth

Tooth germ-related causes

Other causes

Figure 1.5 (A) Agenetic lower second premolar with retained deciduous second molar. (B) The development of the contralateral premolar is arrested.

Consequences

Prevention and treatment

Figure 1.6 Patient with missing maxillary lateral incisors.

Figure 1.7 The canines of the patient in Figure 1.6 have been moved orthodontically into the locations of the agenetic maxillary lateral incisors. The morphology of the canines may be improved by grinding the cusps and building the lateral margins with composite so that the teeth resemble lateral incisors. Note the presence of only three lower incisors.

1.2.2 Oligodontia

Figure 1.8 Oligodont dentition with hypoplastic and conical teeth. (Courtesy of Department of Oral Surgery, University of Groningen.)

Heredity

1.2.3 Anodontia

Treatment of oligodontia and anodontia

1.3 Hyperdontia

1.3.1 Hypodontia with hyperdontia

Epidemiology

Primary dentition

Permanent dentition

Location

Sex, ethnicity

Syndromes

Non-syndromic multiple supernumeraries

Time of development

1.3.2 Supernumerary permanent teeth

Mesiodens

Figure 1.9 Two mesiodentes in the apical region of the permanent maxillary central incisors. They will not erupt because of their inverted direction.

Figure 1.10 A mesiodens between the maxillary permanent central incisors.

Figure 1.11 Inverted atypical extra tooth in the mandible. The small radiopacity visible on the root of the canine increased over time and resembled a late developing atypical extra tooth.

Table 1.2 Characteristics of conical and tuberculate supernumerary teeth251

Distomolar

Figure 1.12 Distomolar situated behind the third maxillary molar.

Paramolar

Figure 1.13 Paramolar (root and crown) attached to a decayed permanent second lower molar.

Figure 1.14 Paramolar or an atypical third premolar in the maxilla. (Courtesy of J.P. Nolte.)

1.3.3 Supplemental permanent teeth

Incisors

Figure 1.15 Supplemental incisor in the right upper quadrant.

Figure 1.16 Two supplemental teeth in the mandible.

Premolars

Figure 1.17 Late developing supplemental mandibular premolar.

Figure 1.18 Extra premolar considered to be atypical because of its small size.

Fourth molars

Figure 1.19 (A) A supplemental (fourth) molar. (B) Inverted eumorphic fourth molar in the ramus of the mandible.

Canines

Eruption issues related to hyperdontia

Aetiology

Heredity

Morphology

Consequences

Figure 1.20 An erupted mesiodens has resulted in lack of space for the lateral incisor, which has erupted palatally.

Figure 1.21 Malalignment of the teeth in the upper right quadrant as a consequence of an extra premolar.

Treatment

1.3.4 “Extra dentitions”

Natal and neonatal teeth

Figure 1.22 Neonatal teeth.

Epidemiology

Appearance

Aetiology

Consequences

Treatment

Third dentition

1.4 Fusion and partial schizodontia

Figure 1.23 Schematic presentation (lower row) of partial schizodontia (A), complete schizodontia or twinning (B), fusion (C) and concrescence (D). The top panel shows a partially split tooth germ (A), a tooth germ split in two (B), two tooth germs pressed together, presumably resulting in fusion (C), and two tooth germs situated too close together (D).

Figure 1.24 Two broad central double teeth; the incisal notches indicate existence of two components.

1.4.1 Diagnosis

Figure 1.25 Possible fusion of a mesiodens with a regular maxillary central incisor.

Diagnostic criteria: fusion versus partial schizodontia

Morphology

Figure 1.26 (A, B) Examples of permanent posterior double teeth from the upper and lower dentitions. The mirror image-like appearances of the occlusal left and right halves of the tooth (Figure 1.26A) possibly indicate partial schizodontia.

Anatomy

Location by jaw

Crowding

Number of teeth in the dentition

Conclusion

1.4.2 Epidemiology

Figure 1.27 Bilateral mandibular fused anterior teeth, suggestive of fusion between the lateral incisors and canines (see text).

Sex

Syndromes

Bilateral double teeth

Posterior double teeth

Triple and quadruple teeth

Figure 1.28 Two mandibular triple teeth (A). The maxillary triple tooth (B) was functional until its shedding. (Courtesy of M.A.C.J. Wevers.)

Solitary symmetrical median central incisor

1.4.3 Aetiology

Evolution

Trauma

Environment

Heredity

Twins

1.4.4 Pathogenesis

1.4.5 Consequences

1.4.6 Treatment

Figure 1.29 (A–D) A double tooth, consisting of conjoined crowns with a common pulp chamber. After hemisection, the mesial part of the tooth was removed and the exposed pulp was treated with direct pulp capping. The resulting diastema was closed orthodontically. (Courtesy of M.H. Ree.)

Figure 1.30 Crown of a first molar fused with a second lower molar.

1.5 Concrescence

Figure 1.31 Concrescence of a second and third molar and a rare case of concrescence of three molars. The left maxillary first molar in the top panel was extracted because of extensive caries; but unexpectedly, the two other molars were extracted as well.

2 Deviations in Tooth Morphology and Size

2.1 Introduction

Figure 2.1 Underdeveloped lingual half (the “deuteromere”) of a maxillary second premolar.

Figure 2.2 Palatal surface of a lobodont maxillary canine (lower panel) and another viewed from labial aspect (upper panel).

2.2 Compression

2.2.1 Appearance and aetiology

Crown

Figure 2.3 (A,B) Compression: a third molar with an underdeveloped mesial aspect due to the already calcified crown of the upper second molar being pressed against the uncalcified mesial side of the third molar during its development. Note the large enamel pearl. (C) The shape of this maxillary second molar crown – broad buccolingually but small mesiodistally – is not a result of compression, but represents the rhomboid crown type.

Root

Figure 2.4 Sickle-shaped root of a permanent upper incisor.

Figure 2.5 Corkscrew root form of a premolar.

Figure 2.6 Curved root of the third molar as a consequence of erupting around the second molar.

2.2.2 Epidemiology

2.3 Dens invaginatus

Figure 2.7 Schematic drawings of dens invaginatus: green represents the enamel, yellow the dentine and pink-red the pulp cavity. The left panel shows a lingual foramen caecum. A deepening of the foramen caecum leads to formation of dens invaginatus: if restricted to the crown of the tooth the anomaly is considered to be dens invaginatus type I (middle panel). The right panel illustrates a deep invagination (type II).

2.3.1 Coronal

Figure 2.8 Dens invaginatus in a permanent maxillary right lateral incisor (A); and the sectioned tooth (B).

Figure 2.9 Dens invaginatus in the mandible.

Association with other anomalies

2.3.2 Apical

2.3.3 Lateral

2.3.4 Epidemiology

2.3.5 Aetiology

2.3.6 Consequences

Caries

Pulpitis

Periodontal problems

2.3.7 Prevention of complications and treatment

2.4 Palato-gingival groove

2.4.1 Appearance

Figure 2.10 Lingual groove running from the enamel onto the root.

2.4.2 Epidemiology

2.4.3 Aetiology

2.4.4 Consequences and treatment

2.5 Dilaceration

Figure 2.11 (A) Dilacerated crown of a mandibular permanent lateral incisor; the lingual surface is visible instead of the labial surface. (B) X-ray showing a dilacerated tooth.

Figure 2.12 Dilacerated root of a lower first premolar.

2.5.1 Aetiology

2.5.2 Prevalence

2.5.3 Consequences

2.5.4 Treatment

2.6 Enamel pearls and enamel extensions

2.6.1 Enamel pearls

Epidemiology

Figure 2.13 Enamel pearl.

Histology

Aetiology

Consequences and treatment

2.6.2 Enamel extensions

Figure 2.14 Cervical enamel extension.

Figure 2.15 Enamel projection with a thick spherical end.

Epidemiology

Aetiology

Consequences

2.7 Fused roots

2.7.1 Aetiology

2.7.2 Epidemiology

2.7.3 Consequences

2.8 Macro- and microdontia

2.8.1 Normal tooth size

2.8.2 Macrodontia

Aetiology

Figure 2.16 Macrodont permanent upper canine (38 mm) and some microdont third molars.

2.8.3 Microdontia

Figure 2.17 Microdont teeth (the partly visible matchstick is of regular size).

Aetiology

Epidemiology

Rhizomicry

Figure 2.18 Permanent upper central incisors with microdont roots (rhizomicry) and an incisor (top) with average root length.

Figure 2.19 Radiograph of upper premolars with “ogee” roots.

Aetiology

Treatment

2.9 Other developmental anomalies of the tooth crowns

2.9.1 Shovel-shaped incisor

Figure 2.20 Shovel-shaped maxillary lateral incisor with a central amalgam filling.

Epidemiology

Treatment

2.9.2 T-shaped, Y-shaped and stellate incisors

Figure 2.21 T-shaped permanent maxillary lateral incisor.

Figure 2.22 Y-shaped permanent maxillary lateral incisor. The combination of the T- with the Y-shape results in a crown resembling a crosshead screwdriver.

Treatment

2.10 Extra cusps

Figure 2.23 Carabelli cusps on the mesio-palatal surface of the permanent maxillary first and second molars.

2.10.1 Dens evaginatus

Appearance

Figure 2.24 (A) Bilateral dens evaginatus. (B) A conical evagination.

Epidemiology

Pathogenesis

Consequences

Treatment

2.10.2 Talon

Appearance

Figure 2.25 (A) Talon. (Courtesy of Gregori M. Kurtzman.) (B) Double semi-talon.

Aetiology

Epidemiology

Consequences

Treatment

2.10.3 Carabelli’s cusp

Treatment

2.10.4 Paramolar tubercle/cusp, paramolar roots, paramolars

Figure 2.26 Paramolar tubercle (arrow) at the mesio-buccal surface of the permanent upper second molar.

Treatment

2.11 Supernumerary roots

2.11.1 Bifid roots

Figure 2.27 (A) Permanent upper lateral incisor (left) and lower canine (right) with bifid roots. (B) Deciduous lower left canine with three roots (in microsomia type I).

Figure 2.28 The buccal roots of these second upper premolars are split into mesial and distal parts.

Figure 2.29 A lower second premolar with a root split into mesial and distal parts.

Figure 2.30 Permanent first upper molar with two mesio-buccal roots, united by a thin sheet of dentine.

Table 2.1 The proportion of teeth with cleft roots

Table 2.2 Teeth showing incidental bifid roots

Figure 2.31 A permanent upper central incisor with an additional small-sized root.

Treatment

2.11.2 Additional roots

Figure 2.32 Paramolar root (left) and a lingual molar root (right).

Radix distomolaris

Radix entomolaris

Figure 2.33 X-ray of first molar with a lingual molar root, originating distally.

Accessory roots

2.12 Taurodontism

2.12.1 Appearance

Figure 2.34 (A) A sectioned taurodont molar. (B) X-ray of an extracted taurodont upper premolar. Note the cylindrical form and the broad apex. (C) X-ray of an extracted taurodont lower premolar. (D) An extracted taurodont upper molar. (E) X-ray of the tooth shown in (D). (F) Endodontically treated taurodont upper molar.