Dental Prosthesis & Tooth-Related Factors PDF

Dental prosthesis and tooth‐related factors Dr. Tarek Mahmoud Eltayeb Lecturer of Oral Medicine, Periodontology and Diagnosis, MIU PHD of Oral Medicine, Periodontology and Diagnosis, Ain Shams University Laser Fellow-Ship, Aachen Laser Center, Germany  Student’s Learning outcomes (S...

Dental prosthesis and tooth‐related factors Dr. Tarek Mahmoud Eltayeb Lecturer of Oral Medicine, Periodontology and Diagnosis, MIU PHD of Oral Medicine, Periodontology and Diagnosis, Ain Shams University Laser Fellow-Ship, Aachen Laser Center, Germany  Student’s Learning outcomes (SLOs) By the end of this course, the student should demonstrate comprehensive knowledge and clear understanding of the following: By the end of this topic, you should be able to: 1) Determine the factors related to the presence, design, fabrication, delivery, and materials of tooth‐supported prosthesis on the periodontium. 2) Identify supracrestal attachment and their variability and methods of assessment. 3) Identify the effect of the restoration margins on the supracrestal attached tissues. 4) Identify the effect of tooth anatomy and position on plaque retention. 5) identify the role of dental calculus in the development and progression of periodontitis.  What is the aim of this lecture? To know current evidence about the role that the fabrication and presence of dental prosthesis and tooth‐related factors have on the initiation and progression of gingivitis and periodontitis. ◦ The anatomy ◦ Presence ◦ Position ◦ Design ◦ Relationships of teeth within the dental arches ◦ Fabrication, delivery ◦ Materials of tooth‐supported prosthesis localized increase in plaque accumulation and, less often, to traumatic and allergic reactions to dental materials  Dental prosthesis and tooth‐related factors to be discussed Biological Width Fixed dental restorations and prosthesis The anatomy of the periodontium of teeth Dental materials Removable dental prosthesis Tooth anatomy and position Cervical enamel projections (CEP) and enamel pearls (EP)s  1-Biological Width What is the biological width??(Supra-crestal attachment) It is defined as the cumulative apical–coronal dimensions of the junctional epithelium (JE) and supra-crestal connective tissue attachment (SCTA)  Is it fixed or variable? How to asses? Dimensions of JE and SCTA can vary ✔ Histology. (most accurate) considerably, regardless of the ✔ Transgingival probing association with other factors such as ✔ Radiographically (in standardized tooth type, surface, biotype, loss of periapical radiographs using parallel attachment, presence of restorations and technique). crown elongation so that it is Can be used to clinically measure the impossible to clearly define a dimensions of the dento-gingival “fixed” biologic width unit, but are not appropriate to measure dimension. the true biologic width. Bone sounding: han7es b resistance gamda gingival margin It is the total distance from the gingival crest to the alveolar crest. This procedure is termed bone sounding. The tissues are anesthetized, and the periodontal probe is placed in the sulcus and pushed through the attachment apparatus until the tip of the probe engages alveolar bone. ?? Supracrestal attached tissue = Bone sounding measurement – PD Kois (1996) proposed three categories of biologic width based on the total dimension of attachment and the sulcus depth following bone sounding measurements, namely: Normal Crest , High Crest and Low Crest  Bone sounding: (a) Normal crest showing biologic width on labial and interproximal (b) High crest showing biologic width on labial and interproximal site (c) Low crest showing biologic width on labial and interproximal site Accordingly, it is recommended that there be Normal crest 3 mm between the preparation margin/finish line and alveolar bone and this was found to maintain periodontal health. This 3 mm constitutes for 1 mm supracrestal connective tissue attachment, 1 mm junctional epithelium and 1 mm for gingival sulcus on an average. This allows for adequate biologic width even when the restoration margins are placed 0.5 mm within the gingival sulcus to maintain gingival health. Carranza’s Periodontology  What are the sequalae of supra-crestal tissue violation? It has been theorized that infringement on the biologic width by the placement of a margin of a restoration within its zone may result in gingival inflammation, pocket formation, and alveolar or crestal bone loss.  Comparing crowns with interproximal margins placed within varying distances from the alveolar bone crest Groups: I = < 1 mm between crown margin and alveolar crest high II = 1 to 2 mm normal III = > 2 mm) low It was observed that, while the presence of supragingival plaque was not different among groups, papillary bleeding index(PBI) was greater in group 1, which was associated with increased probing depths (PD) and a clear encroachment of the crown margins within the supra-crestal tissue attachment. Conclusion Given the limited available evidence in humans, it is not possible to determine if the negative effects on the periodontium associated with restoration margins located within the supra-crestal tissue attachment is caused by Trauma ??? Bacterial plaque?? Combination ??? 2-Fixed dental restorations and prostheses For class II restorations, gingival inflammation is significantly greater around subgingival margins compared with supragingival margins, even when supragingival plaque levels are not significantly different from pre restoration levels.  For Direct restorations Overhangs greater than 0.2 mm are associated with crestal bone loss. Overhanging margins PD, gingival inflammation interproximal bone loss. How to Manage?? The removal of the overhangs during scaling and root debridement causes a resolution of the gingival inflammation and a decrease in PD due to : ✔ Gingival recession (GR) similar to the resolution of gingivitis. ✔ From a microbiologic standpoint the elimination of amalgam overhangs during periodontal therapy caused a decrease of Aggregatibacter actinomycetemcomitans and increase of Streptococcus mutans.  For Indirect restorations Overhangs 〉0.2mm (0.5-1mm) are associated with an increase in gingival inflammation and a more apical crestal bone level Other studies showed that subgingival margins were associated with increased signs of gingival inflammation and, increases in PD. These changes are likely caused by the overhang acting as a plaque‐retentive factor and causing a qualitative shift toward a subgingival cultivable microflora more characteristic of periodontitis. Patient Compliance ◦A clear association is found between periodontal health and patient compliance with self‐performed plaque control and periodontal maintenance after prosthodontic therapy with fixed dental prostheses.  Prosthodontic procedures Tooth preparation ◦ Prosthodontic procedures Impressions May be contributing factors required for the for the development of fabrication of fixed gingivitis, gingival recession, prostheses can negatively Luting agents and periodontitis. affect the periodontium. Provisional restorations increases plaque retention The available literature supports the conclusion that a direct restoration with subgingival margins can be associated with localized gingivitis and increases in PD. A direct or indirect restoration with overhanging margins can be associated with localized gingivitis, increase in PD, and interproximal bone loss, especially for larger overhangs. Permanent changes to the periodontium, such as gingival recession, could occur when subgingival margins are adopted for prosthesis design; however, they appear to be mostly related to trauma to the periodontium exerted by the procedures, instruments, and materials required to place and record the margins in a subgingival location, rather than the position of the margin. 3-The Anatomy of the periodontium of teeth The anatomy of the periodontium of teeth receiving crowns should be evaluated to minimize the likelihood of gingival recession because the presence of an initial shallow PD and narrow band of gingiva negatively influenced the level of periodontal attachment after crown delivery. These studies point out the critical importance of including a complete periodontal assessment prior to prosthodontic manipulations  4-Dental Materials Material Surface Type characteristics Different alloys used to Roughness fabricate onlays and other types of prosthesis showed A minimum roughness threshold similar levels of plaque and (Ra < 0.2 μm) has been suggested gingival inflammation Therefore, available evidence demonstrates that different dental materials act similarly to enamel as plaque‐retentive factors to initiate gingivitis. Metal ions and metal particles can also be released from dental alloys and can be found locally within plaque, the periodontium, and in several organs and tissues. Metal ions and particles, especially Ni and Pd, have also been associated with hypersensitivity reactions which might clinically appear as gingivitis, localized in the area of gingival Gingivitis contact with the dental material. 5-Removable dental prostheses Distal extension RDPs indicate that a favorable periodontal prognosis may be expected provided the following conditions are satisfied: 1) Periodontal disease, if present, is treated and an adequate preprosthetic plaque control regimen established 2) Periodontal health and oral hygiene are maintained through self‐performed plaque control measures and periodic maintenance appointments 3) Patient's motivation is reinforced to enhance compliance to self‐performed plaque control and periodontal maintenance. ❖ In addition, especially distal extension RDPs, when not properly maintained and relined, have the potential to apply greater forces and torque to the abutment teeth, causing a traumatic increase in mobility. 6-Tooth anatomy and position: Cervical enamel projections (CEP) Have been associated with: ✔ Furcation invasion betzawed el PD ✔ Increased PD ✔ Loss of clinical attachment. The extent of CEP extension toward the furcation area can be classified into three classes Grade I described as “distinct change in cemento‐enamel junction (CEJ) attitude with enamel projecting toward the furcation Grade II, “the CEP approaching the furcation, but not actually making contact with it;” Grade III, “CEP extending into the furcation proper. Enamel pearls (EP) Enamel pearls are generally spheroidal in shape, occur in roughly 1% to 5.7% of all molar teeth, vary in dimension from 0.3 to 2 mm, and occur most often isolated on a tooth, potentially localized in the furcation area of molars. EP can act as a plaque‐retentive factor when periodontitis progresses to the point that they become part of the subgingival microbial ecosystem. Developmental grooves The most frequent developmental groove appears to be the palatal groove, most often located in the maxillary lateral incisor 40% of grooves do not extend more than 5 mm apical to the CEJ and only 10% are present 10 mm or more apical the CEJ. The mechanism suggested for developmental grooves to initiate periodontal disease is related to plaque retention that causes localized gingivitis and periodontitis. Grooves are also present on other teeth and mostly in the interproximal areas, with few of these grooves extending to the tooth apex Tooth and root fractures Root fractures ◦ If tooth fractures occur coronal to the Root fractures can be classified based on the : gingival margin and do not extend to parts of the tooth surrounded by Trajectory of the fracture (vertical or oblique), periodontal tissues, they do not initiate gingivitis or periodontitis, unless the surface their Extent (complete or incomplete), characteristics of the fracture area predispose Location (apical, midroot and cervical regions) to greater plaque retention. While fractures located within the midroot and apical regions were shown to have a very favorable prognosis Fractures located within the cervical one‐third of the root had a significantly worse prognosis for tooth retention Since fractures located within the cervical third of a root have a more likely possibility of being colonized by subgingival plaque, they can act as plaque‐retentive factors and indirectly cause gingivitis and periodontitis. In addition, they can directly traumatize the surrounding periodontium due to mobility of the fractured tooth surfaces. Vertical root fractures are defined as longitudinal fractures that might begin on the internal canal wall and extend outward to the external root surface. They occur most often on, endodontically treated teeth although they can be present on non‐endodontically treated teeth, especially molars and premolars, as a result of apical extensions of coronal tooth fractures. A localized pocket, is usually associated with the fractured tooth and extends to variable lengths along the fracture line. Narrow, deep osseous defects are generally seen during surgical exposure of the fractured area with bone resorption and inflammation related to bacterial infection from the gingival margin and root canal system Root resorption Root resorption can be classified depending on its location, as internal or external, cervical or apical. When root resorption is located within the cervical third of the root, it can easily communicate with the subgingival microbial ecosystem. Plaque retention at such sites can cause gingivitis and periodontitis. Cemental tears Are localized areas of cementum detachment from the underlying dentin and can potentially lead to localized periodontal breakdown.  Tooth position ◦ Cross‐bite, misalignment/rotation of a tooth, and crowding of the maxillary and mandibular anterior sextant have been shown to be associated with increased plaque retention and gingivitis, greater PD, and bone and clinical attachment loss. ◦ Tooth position and periodontal biotype and their interaction can also be factors that influence the likelihood of mucogingival deformities, as it has been shown that a thin periodontal biotype has a significantly thinner labial bone plate. In subjects who exhibit trauma related to tooth brushing or tooth malposition within the alveolar process, a greater risk for gingival recession can be present. Tooth anatomy, and specifically the shape of the tooth and their approximation, have been shown to affect the height of the interproximal papilla. Open contacts The presence of adequate proximal tooth contacts is considered important to prevent food impaction between teeth. From a periodontal standpoint, while the presence of open contacts was not a factor directly associated with increased gingival inflamation and PD, the statistically greater occurrence of food impaction at sites with open contacts was associated with increased PD in these areas  Role of Dental Calculus in the development and progression of periodontitis. The primary cause of gingival inflammation is bacterial plaque. Other predisposing factors include calculus, faulty restorations, complications associated with orthodontic therapy and the use of tobacco. ❖ Calculus can be defined as a hard deposit that is formed by mineralization of dental plaque on the surfaces of natural teeth and dental prosthesis which are usually covered by a layer of unmineralized plaque  Classification Dental calculus is classified by it’s location on a tooth surface as related to the adjacent free gingival margin: Supragingival Calculus Dental calculus Subgingival Calculus Supragingival calculus Location: ▪ On the clinical crown, coronal to the margin of the gingiva and visible in the oral cavity Distribution. ▪ Most frequency are on the lingual surfaces of the mandibular anterior teeth opposite to Warton’s duct, and on the buccal surfaces of the maxillary molars opposite to Stenson duct. ▪ Crown of teeth out of occlusion and non-functioning, or teeth that are neglected during daily plaque removal Subgingival calculus Location: ▪On the clinical crown apical to the gingival margin usually in periodontal pockets ▪Not visible upon direct oral examination ▪Extends to bottom of the pocket and follows contour of the soft tissue attachment ▪Occurs with or without associated supra gingival deposits Non-mineralized dental biofilm entraps particles from the oral cavity, including large amounts of oral bacteria, human proteins, viruses and food remnants, and preserves their DNA. contour As a mechanical effect of mineralization of biofilms and spreading, the epithelium is displaced around the gingival line and allows bacteria from living, nonmineralized biofilms to move closer to the alveolar bone. The presence of calculus may limit the ability to perform optimal oral hygiene practices and hence may increase the rate of biofilm deposition. primary - dental plaque biofilm Moreover, subgingival calculus may serve as a secondary retentive site for toxic bacterial products. Dental calculus is an ideal breeding environment for bacterial biofilm and it is accepted as an important secondary etiological factor in the development and progression of periodontitis.