# 126 RESTORATIVE / PERIODONTICS                                    

HOME PERIO TOPICS 

Rapid Search Topics

Oral Surgery – Perio

Restorative Dentistry- Perio

# 125 ORAL SURGERY / PERIODONTICS

1. Should the recommendation for third molar removal be made to every patient? Are these teeth more susceptible to periodontal breakdown? What affect does third molar removal have on the periodontium of adjacent teeth?

1. Osborne WH, Snyder AJ, Tempel TR. Attachment levels and crevicular depths at the distal of mandibular second molars following removal of adjacent third molars. J Periodontol. 53:93-95, 1982.

2. Kugelberg CF, et al. Periodontal healing two and four years after impacted lower third molar surgery. A comparative retrospective study. Int J Oral Surg 1990; 19: 341-345

3. Giglio J, Gunsolley J, Laskin D, Short K. Effect of removing impacted third molars on plaque and gingival indices. J Oral Maxillofac Surg 1994; 52: 584-587

4. Kan KW, Liu JKS, et al. Residual periodontal defects distal to the mandibular second molar 6-36 months after impacted third molar extraction. J Clin Periodontol 29:1004-1011, 2002.

1. If patients are having maxillofacial surgery, are there any particular concerns with the periodontium about which they should be advised? Do osteotomy cuts damage the periodontium?

1. Schultes G, Gaggl A, Karcher H. Periodontal disease associated with interdental osteotomies after orthognathic surgery. J Oral Maxillofac Surg 56:414-417,1998.

2. Foushee D, et al. Effects of mandibular orthognathic treatment on mucogingival tissues. J. Periodontol. 56:727- , 1985.

# 126  Restorative Dentistry / Periodontics

Non-Implant Supported Fixed and Removable Prosthesis

1. Discuss periodontist/restorative dentist interactions, especially with regard to treatment planning and maintenance. What factors are important to consider for long term success? Does the position, material or span of replaced dentition change any of these factors? What common complications are seen with fixed restorations?

1. Maynard J., Wilson, R: Physiologic dimensions of the periodontium significant to the restorative dentist. J Periodontol 50:170, 1979

2. Gracis, S et al: Biological integration of aesthetic restorations: Factors influencing appearance and long –term success. Periodontol 2000 27:29-44, 2001

3. Kois, J: The restorative-periodontal interface: Biological parameters. Periodontol 2000 11:29-38, 1996

4. Nyman S, Lindhe J. A longitudinal study of combined periodontal and prosthetic treatment of patients with advanced periodontal disease. J. Periodontol. 50:163-169, 1979.

5. Goodacre C. et al. Clinical complications in fixed prosthodontics. J Prosthet Dent. 2003 Jul;90(1):31-41

1. What are some considerations for the margin placement and morphology of dental restorations? How can this affect the periodontium? Can dental treatment of the coronal aspect of a tooth cause changes in the clinical attachment? In the microbial population? How does the periodontal condition of a tooth affect the restorative plan?

1. Jeffcoat MK, Howell TH : Alveolar bone destruction due to overhanging amalgam in periodontal disease. J. Periodontol. 51:599-602, 1980.

2. Lang N, Keil R, Anderhalden K : Clinical and microbiological effects of subgingival restorations with overhanging or clinically perfect margins. J. Clin. Periodontol. 10:563-578,1983.

3. Pack ARC, Croxhead LJ, McDonald BW : The prevalence of overhanging margins in posterior amalgam restorations and periodontal consequences. J. Clin Periodontol.17:145-152, 1990.

4. Rodriguez-Ferrer HJ, Strahn JD, Newman HN. Effect on gingival health of removing overhanging margins of interproximal subgingival amalgam restorations. J Clin Perio 7:457-462, 1980.

5. Wang, H et al: The relationship between restoration and furcation involvement on molar teeth. J Periodontol 64:302-305, 1993

6. Silness J : Periodontal conditions in patients treated with dental bridges. II. The influence of full and partial crowns on plaque accumulation, development of gingivitis and pocket formation. J.Periodontal Res. 5:219-224, 1970.

7. Valderhaug J et al: Oral hygiene, periodontal conditions and carious lesions in patients treated with dental bridges. J Clin Periodontol. 1993 Aug;20(7):482-9.

8. Nyman S, Ericsson I : The capacity of reduced periodontal tissues to support fixed bridgework. J. Clin. Periodontol. 9:409-414, 1982.

9. Lee HE, Wang CH, Chang GL, Chen TY. Stress analysis of four-unit fixed bridges on abutment teeth with reduced periodontal support. J Oral Rehab 1995; 22:705-710. 

1. Describe the crown lengthening procedure. What anatomic considerations must be taken into account? How constant is the biologic width? Is it the same for all patients? How do we determine whether or not bone or soft tissue needs to be removed? What flap design would be needed for clinical crown lengthening?

1. Gargiulo A, Wentz F & Orban B: Dimensions and relations of the dentogingival junction in humans. J. Periodontol. 32:261-267, 1961.

2. Barboza E et al. Supracrestal Gingival Tissue Measurement in Healthy Human Periodontium. Int J Periodontics Restorative Dent 2008,28:55-61.

3. Perez J et al: Clinical Evaluation of the supraosseous gingivae before and after crown lengthening. J Periodontol 2007:78:1023-1030

4. Herrero F, Scott J, Maropois P, Yukna R A. Clinical comparison of desired versus actual amount of surgical crown lengthening. J Periodontol 1995:66:568-571.

5. Bragger, et al: Surgical lengthening of the clinical crown. J Clin Periodontol 19:58-63, 1992

6. Pontoriero R et al: Surgical crown lengthening: A 12-month clinical wound healing study. J Periodontol 72:841-8, 2001

7. Deas D., et al: Osseous surgery for crown lengthening: A six month clinical study. J Periodontol, 2004 Sep. 75(9):1288-94

8. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of the bone on the presence or absence of the interproximal dental papilla. J Periodontol 1992; 12: 995-996

1. How does esthetic crown lengthening differ from functional crown lengthening? What treatment parameters must be considered prior to surgery? What information about the final restoration is needed to correctly plan? Are there differences if restorations are involved? When is periodontal treatment not enough?

1. Jorgensen M, Sowzari H: Aesthetic crown lengthening. Periodontol 2000 27:45-58, 2001

2. Garber, D., Salama M: The aesthetic smile: Diagnosis and treatment. Periodontol 2000 11-28, 1996

3. Robbins JW: Differential diagnosis and treatment of excess gingival display. Pract Periodont Aesthet Dent. 11(2):265-272, 1999

4. Wise MD : Stability of gingival crest after surgery and before anterior crown placement. J Prosthet Dent 1985; 53: 20-23

5. Carnevale G, di Febo G, Fuzzi M. A retrospective analysis of the perio-prosthetic aspect of teeth re-prepared during periodontal surgery. J Clin Perio 17:313-316,1990.

1. What are the ways in which restorative materials can affect gingival tissue? How would you address changes in oral mucosa that appear soon after a restoration? What if it is a new patient and an older restoration?

1. Dragoo MR, Williams GB : Periodontal tissue reactions to restorative procedures. Part I. Int. J. Perio. Rest. Dent. 1(1):9-24, 1981.

2. Dragoo MR, Williams GB : Periodontal tissue reactions to restorative procedures. Part II Int. J. Perio. Rest. Dent. 2(2):35-46, 1982. 

1. What important considerations must be taken in to account when designing RDPs for patients with periodontally compromised dentition? How does the tissue react on perio healthy patients?

1. Petridis H, Hempton TJ. Periodontal considerations in removable partial denture treatment: a review of the literature. Int J Prosthodont. 2001 Mar-Apr;14(2):164-72.

2. Bissada N, et al. Gingival response to various types of removable partial dentures. J Periodontol. 45:651-659, 1974.

3. Wright PS, Hellyer PH. Gingival recession related to removable partial dentures in older patients. J Prosthet Dent 74:602-607,1995.

4. Hansen C, Clear K, La Mar S. Removable partial denture design considerations where periodontally compromised teeth exist. Int J Periodont Rest Dent 1997; 17: 89-93.

1. What kind of splints exist? How does splinting affect the periodontium? What is the relationship between splinting and mobility? When do we offer splinting as part of restorative treatment?

1. Glickman I, Stein RS, Smulow JB. The effect of increased functional forces upon the periodontium of splinted and non-splinted teeth. J. Periodontol. 32:290 – , 1961.

2. Kegel W, Selipsky H, Phillips C : The effect of splinting on tooth mobility. I. During initial therapy. J. Clin. Periodontol. 6:45- , 1979.

3. Serio FG. Clinical rationale for tooth stabilization and splinting. Dent Clin NA 43:1-6,1999.

1. Are tooth-retained overdentures a valid treatment option? For whom would this be a good option? What complications can be associated with this therapy?

1. Lauciello, F Ciancio, L: Overdenture therapy: A longitudinal report. Int J Perio Rest Dent. 4:63, 1985

---

125  ORAL SURGERY / PERIODONTICS

1. Should the recommendation for third molar removal be made to every patient? Are these teeth more susceptible to periodontal breakdown? What affect does third molar removal have on the periodontium of adjacent teeth?

Osborne 1982                    ARTICLE
Purpose:  To determine whether definitive root planing and curettage would influence the periodontal attachment and crevicular depth on the distal of second molars, following removal of impacted and partially erupted 3rd molars.
Materials and methods:  18 pts (18-25 years old) with similar bilateral impactions classified as either bony or soft tissue impaction or as partially erupted.  PD measured at distobuccal, mid-distal and distolingual of 2^nd molars. CAL was measured from cusp tips and marginal ridge to base of pocket.  Also assessed GI and PI.  On left side (test side), the distal root of the 2nd molar was planed and the tissue curetted and sutured after extraction of 3^rd molars.  On the right side (control side), neither curettage nor root planing was done following 3d molar extraction.  Measurements, indices, impressions, radiographs and clinical photographs were made pre-op, 3 months and 1 year after 3d molars removal (15/18 returned for 3 month and 1 year follow-up).
Results:  NSSD were seen in PD average (3.8 control vs. 3.4 exp.), attachment level (5.5 control vs. 4.8 exp.), GI or PI.  The results were the same for all the three classes (bony impactions, tissue impactions, and partially erupted) of third molars.
Conclusion: The results of this study support the findings of Ash that root planing of adjacent 2nd molars is of little value in reducing post-op crevice or inducing reattachment.  The best means of preserving periodontal attachment may be the removal of 3rd molars at an early stage of tooth development.

Kugelberg 1990                    ARTICLE                   perio status of second molars
Purpose: To compare the periodontal condition of the adjacent 2^nd molar 2 and 4 years after impacted mandibular 3^rd molar extraction with special emphasis on age.
Materials and methods:

1. 51 subjects (23M, 28F, 17-53 years old) selected at random from the retrospective survey.

2. The patients were examined at 2 and 4 years after impacted mandibular 3^rd molar extractions for PI, GI, PD, and radiographic measurements of proximal bone level (BL) and intrabony (IB) defect depth.

3. The patients were divided into two groups for < 25 years old and > 25 years old.

4. Only PDs greater than 3mm were recorded. PDs were divided into two groups: 6mm, and 7mm.

5. The intrabony defects were measured on PA xrays that were taken with and without a perio probe placed in the deepest part of the defect (standarized). The depth of the defect was measured from the CEJ to the bottom of the defect on the PA film (with the probe in place) with a transparent ruler.

Results: 

1. NSSD in the three clinical variables between 2 and 4 years. 

2. At 4 years, 25% of  < 25 years old group and 52% of > 25 years old group had PD of 7mm or more on the distal of 2^nd molars adjacent to the extraction sites. 

3. NSSD in height of the alveolar crest on the distal surface was observed between 2 and 4 years for either group. 

4. SSD between both groups for the alveolar height at both examinations. 

5. Proximal bone levels showed SS improvement in the younger group.  46% of the young patients showed a decrease in IB defects, and 54% were unchanged. 

6. None of the younger patients had increased in (IB) defects but 30% increased in IB in the older group (15% decreased).

7. Intrabony defects 4mm in subjects < 25 yrs were recorded in 17% of the cases 2 years post-op, while present only in 4% of the cases 4 yrs post-op. The older group were 41% after 2 yrs and 44% after 4 yrs.

8. Mean age for decreased PD was 23.5, unchanged 27.8 and increases in the PD depth the mean was 33 years. 

9. All deteriorated cases were >26 years and 73% of improved cases were <25 years.

BL: Younger pts have a better resolution of defects after impacted 3^rd molar extractions. Periodontal healing after mandibular 3^rd molar extractions is a continuing process even after 2 years in young pts. When the need for extraction of the impacted 3^rd molar can be foreseen, it may bebeneficial to perform the procedure at a younger age, specifically under 25 years old

Giglio 1994                    NO ARTICLE
P: To investigate the effect of removal of partially erupted mandibular 3^rd molars on the plaque & gingival indices of other teeth.
M&M: 60 pts were assigned to 3 groups. Group 1 (Ctrl) had 3^rd molars congenitally missing or previously removed, group 2 had asymptomatic, partially erupted 3^rd molars, and group 3 was experiencing acute pain associated with a partially erupted 3rd molar. None of the pts were under periodontal maintenance or active perio tx. PII & GI were recorded in all 4 quads before and 6 weeks after surgery. No OHI were given.
R/Disc: Both GI and Pl improved in the symptomatic group while only the Pl improved in the asymptomatic group. Neither of the test groups scored as low as the control group post-op. This could be either due to a possible bias in the ctrl group toward better OH, or to the fact that healing was not yet complete influencing the pts ability to perform proper OH. Data from the 2^nd molar adjacent to the sx site was analyzed separately showing that these alone were not responsible for the mean score improvement.
BL: The removal of impacted teeth may provide some benefit in terms of improved gingival health by reducing the plaque index.
Cr: short follow-up period

Kan 2002                   ARTICLE
P: 1) describe the periodontal conditions and other associated features of mandibular 2^nd molars after surgical extraction of impacted 3^rd molars.
2) identify the characteristics of impaction patterns which were associated with persistent post-extraction periodontal problems of these 2^nd molars.
M&M: List of patients that had undergone extraction within a 30-month period was generated from the hospital’s computerized records, in the University of Hong Kong.
Eruption pattern of the 3^rd molars and patient data (gender, age, time since extraction, smoking habits and history of scaling since the extraction) were recorded.The pre-extraction panoramic radiograph was studied and the impaction pattern of the 3^rd molars and the presence of a crestal radiolucency indicating loss of crestal bone between the mandibular 2^nd and 3^rd molar were recorded.  Community Periodontal Index (CPI) protocol and the specific clinical condition of the subject mand 2^nd molar (PD, Rec, BOP, suppuration on probing (SOP), tooth mobility and furc involvement) were assessed by two calibrated examiners. Plaque control and presence of caries lesion or a restoration at distal surface of the subject tooth were also recorded.
Results: 158 were examined in the study out of the 321 cases sampled initially from the computer list. 39% of patients were men and mean age 27.7 years. 77% had never smoked, 18% were current smokers and 5% former smokers. 67% had history of scaling after extraction, 49% had left 3^rd molars extraction and 65% were partially erupted. 76% were classified as mesio-angular impactions and 18% were found to exhibit crestal radiolucency on the pre-extraction radiograph. The % of subjects having a highest CPI score of 2,3 or 4 were 53%, 41% and 6% respectively. Periodontal conditions of Mand 2^nd molar 6-36 months following surgical extraction of adjacent impacted 3^rd molar (n=156)

Surface	PPD (mean)	Rec (mean)
D	5.4	0.8	96	5

(SOP) Suppuration on probing 

Plaque was detectable on the distal surface of 87% of subject teeth, 1% showed furcation involvement, 3% had Grade I mobility and 1% Grade II. 6% had caries on the distal and 4% restoration.
PD was correlated with plaque detection at the distal of the 2^nd molar and presence of crestal radiolucency. No association between PD distal of 2^ndmolar and the length of time since surgical extraction of the 3^rd molars.
Conclusion: Periodontal breakdown initiated and established on the distal surface of a mandibular second molar in the vicinity of a ‘mesio-angular’ impacted third molar evidenced by pre-extraction crestal radiolucency in association with inadequate plaque control after extraction can predispose to a persistent localized periodontal problem.

1. If patients are having maxillofacial surgery, are there any particular concerns with the periodontium about which they should be advised? Do osteotomy cuts damage the periodontium?

Schultes 1998                     ARTICLE
Purpose: To evaluate the periodontal situation near interdental osteotomies after orthognathic surgery.
Materials and methods: 
30 patients with Class II malocclusion were studied 4-10 years after orthognathic surgery and orthodontic treatment.
15 anterior maxillary osteotomies, 10 sagittal maxillary splits, 9 Le Fort I osteotomies and 8 anterior mandibular segmental osteotomies were evaluated.
10 patients received ortho before the surgery and 20 patients had orthognathic surgery only.
Panoramic and periapical radiographs were made of the osteotomy region for every patient and the periodontal status was assessed.
A reduction in bone mass of 1/3 of the root length was classified as marginal superficial periodontitis and a further reduction as profound marginal periodontitis.
Post-op tooth loss was confirmed by comparison with pre-op radiographs. Lateral root resorption at the osteotomy sites was recorded.
Results:
51 pathologic periodontal findings in the 74 segmental osteotomy sites.
Periodontal pockets were found in 35 cases and post-op tooth loss in 16 segmental regions.
Average of 1.1 teeth per patient lost because of segmental osteotomies. In addition, 1.2 teeth per segment showed severe damage to the periodontium.
Superficial periodontal lesions were found in 1.7% and deep periodontal lesions in 47.5% of the osteotomy sites. 22% of the osteotomy sites showed a loss of teeth.
Lateral root resorption was present in 15.3% of the osteotomy sites. In the ortho treated patients 7/10 showed apical root resorption of mandibular and maxillary anterior teeth.
BL: A high incidence of dental and periodontal trauma occurs in the region of segmental osteotomies after orthognathic surgery.

Foushee 1985                      ARTICLE
P: To determine if alterations in mucogingival status (recession, width of KG, width of attached gingiva) occur in mandibular anteriors and premolars in patients after chin repositioning (genioplasty)
M+M: 24 patients (12-34 years old, 18 F 6M) evaluated for Orthognathic therapy; orthodontic treatment was performed and then genioplasty with or without mandibular advancement. Pretreatment measurements only on the facial surfaces of mandibular anteriors and premolars: width of KG, PD, recession, and width of attached gingiva. Second evaluation was done between 3 months and 3 years after surgery. 21 patients analyzed statistically looking at centrals, canines, and premolars. 8 patients received maxillary Osteotomies, 6 patients had mandibular advancement, 10 patients had maxillary and mandibular surgeries. 16 / 24 had either mild or moderate gingival inflammation with no PDs > 4 mm preoperative.
R: After Orthognathic treatment: SS decrease in KG for mandibular anteriors (median change = -0.5 mm) but no change for premolars. SS decrease of attached gingival for all teeth after surgery (median change for canines and premolars = – 0.5 mm, median change for incisors= 0). 10 / 24 showed post-treatment recession (4 pts had 0.5mm or less, while 6 pts had 0.5 to 3 mm). 5/6 pts having significant recession post-treatment had mandibular advancement in addition to genioplasty.
BL: The pretreatment width of keratinized and/or attached tissue was not the critical factor in development of recession. Risk of recession increased when genioplasty was combined with mandibular advancement and occur at sites where KG and underlying bone appeared thin.
Cr: All pretreatment measurements were taken by one examiner, and all posttreatment measurements were taken by a different examiner and then they were calibrated and analyzed for agreement.

---

126  Restorative Dentistry / Periodontics
Non-Implant Supported Fixed and Removable

1. Discuss periodontist/restorative dentist interactions, especially with regard to treatment planning and maintenance. What factors are important to consider for long term success? Does the position, material or span of replaced dentition change any of these factors? What common complications are seen with fixed restorations?

Maynard 1979                    ARTICLE
D: When treating patients, the objectives of restorative therapy must be clear. The first and most basic objective is preservation of the teeth. The attainment of this objective would be far less complex if it could be considered independent of restoration of function, comfort and esthetics, but such is not the case. The latter objectives usually require sophisticated restorative dentistry and often include restorations with intracrevicular margins. Although it is widely accepted that the best restorative margin is one that is placed coronal to marginal tissue, most restorations have margins in the gingival crevice, and permanent tissue damage is common. In attempting to reach his objective, the restorative dentist must remember the fundamental precept of the health professions, which is: Do no harm. Daily observation of the three physiologic dimensions permits the therapist to restore teeth with minimal injury to the periodontium.

Gracis 2001                    ARTICLE
P: To discuss factors that determines the esthetic and long term success of esthetic restorations.
D:
Anatomical consideration
Biologic Width: Many authors have highlighted the inevitability of penetrating the epithelial attachment during the prosthetic procedures without causing any irreversible damage. Therefore, nowadays, ‘‘true’’ biological width violation means the placement of a restorative margin in the connective tissue attachment.
Papilla: The height of the interproximal papilla depends not only on the bone architecture but also on the relative tooth proximity: the closer the crowns, the more accentuated the papilla because the soft tissues tend to be supported by the proximal contours of the crowns. When preparing a tooth, the tip of the bur should therefore follow the gingival margin or the anatomic
configuration of the cementoenamel junction.
Thin Biotype: More at risk of recession, place margins supragingival.
Root prominences: Must be recognized for presence of fenestrations or dehiscences,
contraindication to placing margins subgingivally.
Supra vs intracrevicular margins
Supragingival, are easier to temporize, take impressions off, allow assessment of the fit of the restoration, allow margin finishing and burnishing, and facilitate plaque removal. Intracrevicular restorations cause more periodontal problems; this might be due to defective margins, inaccurate fit, roughness of the tooth–restoration interface, improper crown contour, violation of the connective tissue attachment, and greater pathogenicity of the subgingival dental plaque.
Factors that may force the clinician to place a restoration margin intracrevicularly:
– Need to improve the resistance and retention form of a short clinical crown
– Presence of caries or restorations extending apical to the gingival margin
– Modification of the emergence profile
– Aesthetics.
Phase one should be done first, Intrasulcular preparations should be performed exclusively in presence of a healthy crevice: only when it is inflammation free is the gingival margin stable and less prone to recession and can be probed and packed more accurately. Therefore, an intracrevicular margin should be placed 0.2 to 0.5 mm apical to the free gingival
margin on the facial side. Interproximally, because the sulcus normally is deeper, the preparation can extend more apically to better support the soft tissues. Some authors suggest placing a retraction cord in the sulcus before finalizing the preparation.
This maneuver has two advantages: it highlights the base of the sulcus and therefore the ultimate limit of the preparation before causing irreversible damage, and it pushes the gingival margin outward and apically to better expose the unprepared tooth structure to be removed.
The sequence of clinical steps consists of:
– Tooth preparation to the gingival margin
– Placement of an extra-thin knitted retraction cord that displaces the gingiva outward and
apically
– Definitive margin preparation to the top of the cord achieving a new, more apical position.
Provisionals
Protect the prepared teeth, to reduce the sensitivity of the vital abutments, and to prevent tooth migration. They are also instrumental in developing the correct aesthetics, phonetics and occlusal scheme before fabrication of the definitive restoration. More importantly, well-contoured and well-fitting provisional restorations allow the periodontal tissues to stay or become healthy.
Special attention should be dedicated to the development of the proper emergence profile of the provisional prosthesis.
Impression technique
The impression technique can have a negative impact on the soft tissues around the abutments, even causing irreversible damage if the technique is not properly carried out. The objective of tissue retraction is to expose all of the prepared tooth structure and, possibly, a portion of the unprepared root beyond the margin by causing a horizontal and vertical displacement of themarginal gingiva. A single-cord technique is the least traumatic option and is normally employed when the sulcus is shallow and the margin is placed only minimally in the crevice. A double-cord technique is used when the sulcus is deeper. Root proximity may create severe problems in obtaining good impressions because there will not be enough space to accommodate the retraction cords and, subsequently, a proper thickness of impression material. The placement of cords in such restricted interproximal spaces
may cause irreversible damage. Possible solutions to this problem are: partial- instead of full-coverage restorations to
1.Avoid preparing and restoring the side of the tooth with the proximity problem
2.More apical placement of the restorative margin if the root trunk tapers apically or an
odontoplasty with a flame-shaped bur to increase the separation
3.Orthodontic movement to separate the teeth
4.Strategic extractions.
Choice of restoration depends on:
1.Tissue type,
2.Tooth vitality
3.Abutment integrity
4.Abutment height
5.Occlusal clearance for proper strength
6.Aesthetic needs of the patient
7.Parafunctional habits

Posts
Fiber posts are more esthetic, however, may flex which has been associated with loss of the cement lute marginal seal and microleakage. Metal posts are rigid but can negatively affect esthetics.

Preparation design
Preparation designs for full-coverage restorations may be classified into four distinct types:
– Feather-edge: Frequently used for gold crowns and porcelain and composite veneers, lack resistance, and can cause over contouring, use should be limited.
– Chamfer: Widely used because of ease of preparation, however, according to some authors, the thin metal collar may distort during the firing of porcelain, thus producing inaccurate margins. The visibility of the metal does not allow these crowns to be used in areas where the aesthetic demands are high
– Shoulder with bevel: It is more conservative than a full shoulder preparation, but the presence of the metal collar necessitates an intracrevicular preparation in aesthetic areas
– Shoulder: The shoulder is probably the most popular design because it is very easily read by the technician, and it allows sufficient bulk for porcelain to produce aesthetically pleasing restorations

Kois 1996                    ARTICLE
Purpose: To examine several biological parameters looking at the restorative-periodontal interface
Discussion: 

• Bacterial plaque accumulation: Plaque retention depends on surface roughness and the surface energy of the restorative material. The short-term positive gingival response of provisional restorations may not be a good indicator of the long-term gingival health. Mechanical insults such as bands, cord and retraction clamps can disrupt JE and CTA. This might heal with a recession that will self correct in the future. Possibly prescribe CHX for 2-week regimen with OHI if indicated

• Marginal integrity of restoration: Clinical parameters of what constitutes acceptable margin have never been established. Marginal wear or ill-fitting prosthesis might lead to gingival inflammation but not progression of perio dz. 62% of restorations have an opening of at least 200 μm, bacteria generally range from 1-5 μm. 

• Coronal contour must mimic natural teeth. It’s unclear what the definition of over- and undercontoured actually is. As contour is increased in 0.5 mm increments to 1.5 mm greater than original tooth dimension, papillary bleeding increases. This can be a problem for both supra- and subgingival margins. Close root proximity increases the importance of interproximal contour. Slight deviations can compromise the gingival tissue. One should be able to pass an explorer through to sulcus. If not, overcontoured. 

• Alloy sensitivity: Ni containing alloys greatest risk of hypersensitivity. Contact dermatitis is most common mode of adverse reaction.

• Margin location: Subgingival margins tend to be worse for gingival health. Most critical factor appears to be relationship to supracrestal fiber attachment. If margin placed in biologic width, adverse long term health seen. Need to locate the base of the gingival sulcus; however, in varying degrees of inflammation, probe penetrates differently. The osseous scallop is greatest in the anterior and flattens as move to posterior. If do not follow this scallop, may violate the biologic width in one area and not another on the tooth. If the biologic width is violated, might have recession. This depends on biotype and tissue management. 

BL:The proper margin location of restoration relative to the alveolar bone is one of the critical parameter to ensure long-term gingival health

Nyman 1979                    ARTICLE
Purpose: To present the results of periodontal and prosthetic treatment of patients with advanced breakdown of the periodontal tissues.
Materials and methods: 299 individuals were divided in two groups. Group I:non-bridge treatment group (48 patients). A well-functioning dentition could be established with periodontal treatment only. Group II (251 patients): bridge treatment group. Prosthetic treatment was required subsequent to the treatment of periodontal tissues. Following the active phase of treatment, all patients were placed in a maintenance program which included recalls every 3 to 6 months. Patients of Group I have been followed up for 8 years and those of Group II for 5 to 8 years. Following initial treatment and then once a year, the following parameters were assessed: PI, GI, PD, AL, and marginal alveolar bone height. Also, the frequency of and the reasons for technical failures in the bridgework were assessed. 332 fixed bridges were analyzed.
Results: Final examination (8 year follow-up for Group I and 5 to 8 years for Group II) revealed that both groups maintained low plaque scores and gingival indices. In none of the treatment groups, PDs varied in a significant way during the course of the study. Bone level was maintained unchanged in both groups. The analysis of the 332 bridges regarding frequency and reasons for bridge failures revealed:  1) Loss of retention of retainer crowns from abutment teeth (11 bridges, 3.3%), 2) Fracture of bridge (7 bridges, 2.1%), 3) Fracture of abutment tooth (one tooth in 8 bridges, 2.4%).
Conclusion: Following periodontal treatment, periodontal health can be maintained in patients enrolled in a controlled OH program. Supportive periodontal therapy (SPT) in this study was equally effective for patients with bridge work. Severe reduction of periodontal support around abutments and differences in bridgework design did not influence the periodontal status. However, technical failures occurred in 26 out of 332 bridges. These failures appeared as loss of retention, fracture of bridgework, and fracture of abutments.

Goodacre 2003                    ARTICLE
Purpose: To identify the incidence of complications and the most common complications associated with single crowns, FPDs, all-ceramic crowns, resin-bonded prostheses, and posts and cores.
Materials and methods:
Medline and extensive hand search covered the last 50 years and focused on publications that contained clinical data regarding success, failure, and complications.
Results:
Most common single crown complications

	Mean Incidence
Need for endodontic treatment
Porcelain Fracture
Loss of retention
Periodontal Disease
Caries

Most common fixed partial denture complications

	Mean Incidence
Caries	18% of abutments / 8% prosthesis
Need for endodontic treatment	11% of abutments / 7% prosthesis
Loss of retention
Esthetics
Periodontal disease
Tooth fracture
Prosthesis Fracture
Porcelain Veneer fracture

Most common all -ceramic crown complications

	Mean Incidence
Fracture
Loss of retention
Pulpal health
Caries
Periodontal disease	0.0% No significant changes

Most common resin-bonded prosthesis complications

	Mean incidence
Debonding
Tooth discoloration
Caries
Porcelain fracture
Periodontal disease	0.0% No significant changes

Most common post and core complications

	Mean incidence
Post loosening
Root fracture
Caries
Periodontal disease

1. What are some considerations for the margin placement and morphology of dental restorations? How can this affect the periodontium? Can dental treatment of the coronal aspect of a tooth cause changes in the clinical attachment? In the microbial population? How does the periodontal condition of a tooth affect the restorative plan?

Jeffcoat 1980                    ARTICLE                           amalgam overhangs
P: Examine the effects of overhanging amalgams on the alveolar bone height in patients with periodontal disease.
M&M: Examined records of 4600 patients screened for Overhangs. 100 selected with contralateral controls (no overhangs). Overhangs classified as small (occupies< 20% interproximal space), medium (20-50%), large (> 50%). Patients classified as to perio Class I-IV (ADA). Bone loss compared to control measured from CEJ to crest divided by root length using
radiographs.

R:  71% greater bone loss on overhang side vs. control. Small overhangs did not result in SSD vs. control but larger overhangs result in more bone loss. For each periodontal disease type the bone loss around the experimental teeth exceeded the control (5.6% for class I, 6.7% for class II, 12% for class III).
BL: Bone loss from overhanging amalgams is due to plaque retention and inflammation due to impingement of the embrasure space

Lang  1983                    ARTICLE
P: To determine if placement of subgingival restorations with overhanging margins results in change in the subgingival microflora.
M&M: 9 dental students with gingival index scores < 0.1 (pts had SRP and OHI first) requiring 10 gold MOD onlays for caries control. All MOD onlays preps were made with margin 1.0 mm subG;. Each tooth had 2 restorations fabricated: one with clinically perfect margins and one with 1.0 mm proximal overhangs. In a cross-over study, half of the teeth (5) had onlays w/1 mm proximal overhangs for 19-27 weeks that  were then replaced by 5 onlays with perfect margins. Another 5 teeth had onlays with perfect margins placed first (8-24 wks) which were then replaced with the 1 mm overhang MOD onlays (12-27 wks). Patient cleaned normally, except NO IPx cleaning at the site of the onlays. Prior to and every 2-3 weeks after insertion, PI, GI, subG microbiological samples (paper point) and PD to the level of the proximal margin of gold onlay were recorded..
R/D: Without overhangs, no increase in BOP at sites (if overhangs placed first, by the end of 2^nd experimental period BOP had resolved). With overhangs, both groups by end of experimental period were at 100% BOP and GI of 2 or 3. For PD, as GI increased, so did the measurement to the FGM. There was no change from margin to base of sulcus (pseudopocketing with inflammation). With overhangs; there no change in the amount of plaque found subG, but rather the subgingival flora began to resemble chronic perio, w/ increased Gram – anaerobic bacteria, black pigmented Bacteroides (1.6%-3.8%) and increased anaerobe facultative ratio. With clinically perfect margins a microflora characteristic of health or initial Gingivitis was observed. Pts individually had different time frames for developing this flora, indicating host resistance/susceptibility.
BL: Placement of restorations with overhanging subgingival margins result in a change of subgingival microflora to one that may be associated with periodontitis, which documents a potential mechanism for iatrogenic initiation of periodontal disease. Host susceptibility plays a role in the time frame of how long it took to shift to a more peridontopathic microflora

Pack 1990                    ARTICLE
P: To determine prevalence of overhanging margins and associated periodontal status in 100 patients with completed treatment by final year dental students.
M&M: 100 subjects. PD, BOP, and clinically detectable margins recorded on all posterior teeth, and BWs were taken. No attempt to determine size of overhangs.
R: 1319 teeth with 2117 restored surfaces were examined.
– Prevalence: 1186 restored surfaces (56%) had overhangs, 62% of all restored interproximal surfaces
– 62% of distal, 60% mesial, 35% buccal, and 40% of lingual restorations had overhanging margins
– 69% of distal, 54% of mesial restorations next to the edentulous space had overhanging margins
– PDs > 3 mm: 64.3% of overhangs, 23.1% for unrestored surfaces, and 49.2% for non- overhanging restorations
– BOP, 32% of pockets adjacent to overhangs bled on probing, 10.5% for un-restored and 21.6% for non-overhangs.
BL: Periodontal disease was more prone in the presence of poor margins. These overhangs significantly affected the periodontal status of the teeth.

Rodriguez-Ferrer 1980                    ARTICLE
Purpose: To resolve the influence of removal of subgingival overhanging margins on the healing of gingival tissues and to determine whether it should be carried out at the beginning or at the end of the initial phase of periodontal treatment.
M&M: 15 pts with early to advanced periodontitis and 52 proximal surfaces that had confirmed overhanging restorations (amalgam) after removal of subgingival calculus were selected. Test group: 26 overhangs were removed at the first visit (no palpable transition between tooth surface and restoration). Control group: 26 contralateral-paired overhangs were left untreated. Every surface was scored for GI, PI, and PD at 0, 4, 8, 12 wks. Pts received OHI and performed Bass technique, flossing, toothpick and a proxy brush.
Results: After initial exam, NSD was observed in any parameters between test and control groups. By 12 weeks there was a SD for all indices except PD comparing test and control. The greatest change in gingival responses was seen in the first four weeks. Many of the restorations became supragingival as the marginal tissues responded to therapy.
BL: Gingival inflammation is a constant finding in areas related to Class II subgingival amalgam restorations with overhanging margins. Gingival inflammation is due to plaque accumulation in relation to overhangs, which impedes OH. Overhangs should be removed as soon as possible during initial phase of periodontal treatment.

Wang 1993                    ARTICLE
P: Cross sectional study The primary aim was to determine the relationship of crowns, proximal restorations and furcation involvement, and Secondarily was to evaluate the influence of the tooth mobility and endo treatment.
M&M: 134 perio maintenance pt (62 M and 72 F) that had restored and non-restored teeth with or w/o furcation involvement on molar teeth. Most of the restoration margins were supragingival and placed about 5 years prior to the study. 1st and 2^nd molar were examined for the absence of presence of crown type restorations, restorations involving proximal surface, endo tx, furcation involvement, mobility, AL.
Results: 373 of 771 Molars had furcation involvement and 362 had restorations or crowns. 113 were mobile and 37 had RCT. So, molars with crown or restoration had higher prevalence of furc involvement (P<0.01).
 Loss of attachment associated with restorations was marginal(p=0.051), with more loss shown in the maxilla. The diff in AL b/w restored and non-restored molars occurs mostly in the maxillary arch
BL: pts w/ crowns or interproximal restorations are more likely to have furcation involvement and more CAL loss even undergoing regular maintenance.
-self critique: causality cannot be shown by X-sectional studies

Silness 1970                    ARTICLE
P: To compare the periodontal condition of abutments and contralateral teeth in patients with
full and partial crowns used for retaining dental bridges.
M&M: 261 individuals, 242 abutment teeth were compared with 242 contralateral teeth in the same patients. Patients were divided into groups depending on receiving periodontal treatment and OHI or not, location of crown margins (sub-g and no sub-g) and type of crowns (full or partial). Instructed group (159 individuals): this group had received periodontal treatment, OHI instructions and reinforcement 2-6 years before the examination. Non-instructed group (102 individuals): this group had received no periodontal treatment and no OHI. So 4 groups were formed: 1) GROUP I: non-instructed patients, full crowns with sub-g margins, 2) GROUP II: instructed patients, full crowns with sub-g margins, 3) GROUP III: instructed patients, full crowns with no sub-g margins, 4) GROUP IV: instructed patients, partial crowns with no sub-g margins. GI, PI, PD and margin index (position of margin in relation to crest) were recorded.
R: Abutments with complete crowns with full coverage and sub-g margin showed larger
amount of deposits, more severe gingivitis and increased PD compared to contralateral teeth
whether or not patients were instructed on oral hygiene. In instructed patients, the periodontal
condition of abutments with complete or partial crowns with limited coverage and no sub-g margin did not differ significantly from those of control teeth.
BL: Abutment teeth with crowns with subgingival margins are associated with more severe
gingivitis, deeper PD, and increased accumulation of plaque, compared to the uncrowned
contralateral teeth even in patients who were instructed in oral hygiene methods.

Valderhaug 1993                    ARTICLE
P: The aim of the present study was to assess the level of oral hygiene, periodontal conditions, changes of alveolar bone level and prevalence of caries in a group of patients who had received regular oral prophylaxis following the insertion of fixed partial dentures. Differences of these indices when the crown margins initially were located sub-gingivally, at the gingiva or supragingivally were also recorded.
M&M: 102 patients received a total of 108 cast gold or gold/acrylic bond bridges on 343 abutment teeth. The rest of the teeth on the same jaw that received the restorations served as controls. Clinical and radiographic exams were done at baseline, 5, 10, 15 yrs. PI, GI, PD, were measured. Margins placed >1m below the gingival margins were considered sub-gingival. Bone loss was measured to the nearest 0.5mm. Maintenance was offered every 6 months for the first 10 years. Statistical analysis was done.
R: Data at 5 (88 pts), 10 (71 pts) and 15 years (55 pts) recorded. 16 pts had a new bridge made or extraction of an abutment tooth over time (15.7%). There was NSSD for PI between test and control. Pi increased for 21% to 27% during the 15 year observation period. GI 2 and 3 was more frequent on abutment teeth than control, and more frequent on crowns with sub-gingival margins. A slight increase in PD was observed at 5- years at the teeth with sub-gingival margins. At baseline, 79% of surfaces had PD <2mm, 4% had PD >4mm. At 15 years, 57% of sites were <2 mm, while 3% were >4mm. Buccal surfaces had always shallower PDs than the other 3 surfaces. Sub-gingival crown margins decreased from 64% at baseline to 36% at 15 yrs (more pronounced on buccal). Caries were recorded at 3.3% of the abutment teeth at 5th year, 10% at 10^th year, and 12% at 15th year. NSSD in bone loss could be detected between the test and control teeth or between the different crown margins locations.
BL: patients who were seen for regular OH maintained healthy periodontal conditions and relatively low caries. Many subgingival margins were seen at the gingiva or supragingivally after 10 or 15 yr.

Nyman 1982                    ARTICLE
Purpose: To compare the calculated size of the PDL around abutment teeth with the size