Surgical versus non-surgical endodontic re-treatment for periradicular lesions

Factors Affecting the Success of Endodontic Microsurgery: A Cone-Beam Computed Tomography Study

The purpose of this retrospective study was to verify preoperative local parameters of periapical lesions evaluated on cone-beam computed tomography (CBCT) scans as a potential prognostic factor in endodontic microsurgery (EMS). Among 89 cases, local factors (dimensions of lesion, bone destruction pattern, presence/absence of cortical bone destruction, height of buccal bone plate, apical extend of root canal filling, presence/absence of communication with anatomical cavities, type of lesion restriction) were measured on preoperative CBCT images before EMS. At least one year after surgery, the outcome of EMS was classified as a success or a failure. Ten cases (11.24%) were classified as a failure and 79 as a success (88.76%). Symptomatic lesions (OR = 0.088 (95% CI 0.011-0.731); p = 0.024), apicomarginal lesions (OR = 0.092 (0.021-0.402); p = 0.001) and an association with molar teeth (OR = 0.153 (0.032-0.732); p = 0.019) were found as negative predictive factors in the univariate analysis, whereas large apicocoronal dimension (OR = 0.664 (0.477-0.926); p = 0.016), apicomarginal lesions (OR = 0.058 (0.006-0.55); p = 0.013), and an association with molar teeth (OR = 0.047 (0.003-0.869); p = 0.04) were identified as negative predictive factors in the multivariate analysis model. Symptomatic lesions, apicomarginal lesions, lesions associated with molar teeth and large apicocoronal dimensions are significantly associated with the failure of EMS.

Comparison of Endodontic Failures between Nonsurgical Retreatment and Endodontic Surgery: Systematic Review and Meta-Analysis with Trial Sequential Analysis

Background and Objectives: In the presence of a persistent endodontic lesion or endodontic failure, the alternative for the recovery of the dental element is endodontic retreatment or endodontic surgery, which consists in the surgical removal of the root apices with retrograde closure of the endodontium. The objective of this systematic review and meta-analysis was to provide an updated value of the Risk Ratio between the two types of treatment in order to offer to clinicians who propose a non-surgical endodontic retreatment or an endodontic surgery a direct comparison. Materials and Methods: The revision was performed according to PRISMA indications: three databases (PubMed, Scopus and Cochrane register) were consulted through the use of keywords relevant to the revision topic: surgical endodontic retreatment, endodontic retreatment, apicoectomy. This search produced 7568 records which, after eliminating duplicates and applying the inclusion and exclusion criteria, resulted in a total of seven included articles. The meta-analyses were conducted by applying fixed-effects models, given the low percentage of heterogeneity. In addition, trial sequency analysis (TSA) was performed for the analysis of the statistical power of the results and GRADE for the quality of the evidence. Results: The results of the meta-analyses' data report an aggregate risk ratio (RR) between non-surgical endodontic retreatment and surgical endodontic retreatment of: 1.05 [0.74, 1.47] at one year of follow-up; RR 2.22 [1.45, 3.41] at two years of follow-up; an RR 1.08 [0.73 1.62] for a follow-up period of 3-4 years; and an RR 0.92 [0.53, 1.61] for a follow-up period of 8-10 years. Conclusions: The results of the present meta-analysis show that in the long term, the risk of failure is identical for the two groups, and there is only a slightly higher risk of failure for non-surgical endodontic retreatments, when only two years of follow-up are considered.

Investigating the appropriateness of surgical endodontic referrals to a West Sussex regional referral unit

Aim To audit the appropriateness, after triage, of surgical endodontic referrals to Queen Victoria Hospital, a regional referral unit in West Sussex. To discuss the current referral pathway with the aim of improving general dental practitioner (GDP) understanding of indications for surgical endodontics via the referral process.Methodology A three-year retrospective review of all surgical endodontic referrals made to Queen Victoria Hospital, East Grinstead was completed. This was inclusive of all referrals made via the National Health Service (NHS) Vantage Rego e-referral system and GDP referral letters. The quality of referrals was analysed as indicated or contraindicated in accordance with the Royal College of Surgeons guidelines for surgical endodontics and periradicular surgery.Results Out of the 34 referrals included in data analysis, 50% contained one or more contraindication for surgical intervention. The most commonly recorded contraindications to treatment were poor-quality root canal treatment, periodontal disease compromising the long-term success of treatment and a poor coronal seal deeming the tooth unrestorable post-surgical intervention.Conclusions A more efficient surgical endodontic referral system will aid resource allocation within the NHS. These results are a first step to aiding necessary modification of the primary care referral pathway to achieve a more effective service for patients, with improved acceptance rate of referrals and better surgical outcomes.

Healing of Periapical Lesions After Surgical Endodontic Retreatment: A Systematic Review

Background: Surgical root canal retreatment is required when peri-radicular pathosis associated with endodontically treated teeth cannot be treated by non-surgical root canal therapy (retreatment), or when retreatment was ineffective, not feasible or contraindicated. Endodontic failures maybe happen when irritants remain within the confines of the root canal, or when an extra-radicular infection cannot be eradicated by orthograde root canal treatment. Following enhanced microsurgical techniques in the last years, the success rates of surgical root canal retreatment have improved considerably.

Objective: The aim of this systematic review is to gather updated data in regard to the surgical root canal (retrograde) retreatment to heal the periapical lesions.

Materials and methods: The electronic databases PubMed and Google Scholar were searched in this review using specific inclusion and exclusion criteria. The search was performed in June 2019 and updated in November 2019. Among 3900 studies, 10 studies satisfied the eligibility criteria and were included in the review to be analyzed.

Results: The 10 studies showed the importance of surgical root canal retreatment as a treatment option in removing infections within the root canal system and its efficiency in periapical tissue healing. These studies investigated different aspects of healing of periapical lesion after surgical (retrograde) retreatment including success rates, follow-up duration, and updated studies in surgical (retrograde) retreatment.

Conclusions: Surgical root canal (retrograde) retreatment demonstrates its efficiency in reducing the period needed for healing of the periapical lesions in short-term follow-up compared to conventional orthograde retreatment.

Endodontic microsurgery. Part one: diagnosis, patient selection and prognoses

Historically, surgical endodontics has been viewed as a treatment of last resort, mainly due to poor outcomes as a result of limitations in materials and techniques. Contemporary techniques, modern materials and better visualisation have all led to an improvement in success rates, making endodontic microsurgery a valuable treatment option to certain patients. Such advances, however, are no substitute for skill in endodontic diagnosis and treatment planning, which can often prove challenging. A variety of tools are available to test for fractures and assess both periodontal and pulpal health. More advanced techniques such as cone beam computed tomography are often invaluable in pre-surgical assessment and diagnosis. Once an accurate diagnosis has been established, a favourable prognosis is explicitly linked to careful patient selection. Orthograde treatment, or retreatment, remains the gold standard for the majority of endodontic problems. However, there are a number of indications for surgery where orthograde treatment is either impossible, or less likely to be successful. It is paramount for any clinician undertaking endodontic surgery to have a detailed understanding of the local and systemic factors associated with successful treatment. Whilst there are few absolute medical contraindications, there are a number of conditions which may influence patient management and make treatment more challenging.

Oral health-related quality of life (OHRQoL) before and after endodontic treatment: a systematic review

OBJECTIVES

This systematic review was undertaken to determine the oral health-related quality of life (OHRQoL) before and after endodontic treatment.

MATERIALS AND METHODS

Based on the PRISMA guidelines, electronic databases (n = 7) were searched and from 1038 citations, 16 papers were included in this review. Information on study design, sample size, intervention/treatment modality, methods of assessing OHRQoL, and the key findings were extracted and analyzed.

RESULTS

Among the 16 studies, 3 were cross-sectional surveys, 9 were longitudinal studies, and 4 were randomized clinical trials. The cross-sectional studies reported improvements in OHRQoL following root canal treatment. Comparative longitudinal studies did not identify a significant association between improvements in OHRQoL and the method of root canal instrumentation or number of instruments used. Clinical trials found that improvements in OHRQoL were significantly associated with instrumentation technique, surgical-incision approach, and the application of platelet-concentrate during surgery. Several methods of assessing OHRQoL were employed with the most common being the Oral Health Impact Profile (OHIP), albeit using different versions.

CONCLUSIONS

The results of this systematic review indicate that the QoL of patients improved after endodontic treatment. Nevertheless, these results are limited to patients who seek endodontic treatment and cannot be generalized. The lack of well-designed observational studies with standardized assessment approaches, coupled with heterogeneity of study design and interventions, precluded quantitative synthesis.

CLINICAL RELEVANCE

Pragmatic clinical trials are more meaningful to understand patient-centered outcomes of treatment. This review shows that endodontic treatment does improve the QoL. However, future studies should use standardized tools and data reporting, which are critical to make meta-analyses possible.

Single-visit or multiple-visit root canal treatment: systematic review, meta-analysis and trial sequential analysis

OBJECTIVES

Single-visit root canal treatment has some advantages over conventional multivisit treatment, but might increase the risk of complications. We systematically evaluated the risk of complications after single-visit or multiple-visit root canal treatment using meta-analysis and trial-sequential analysis.

DATA

Controlled trials comparing single-visit versus multiple-visit root canal treatment of permanent teeth were included. Trials needed to assess the risk of long-term complications (pain, infection, new/persisting/increasing periapical lesions ≥1 year after treatment), short-term pain or flare-up (acute exacerbation of initiation or continuation of root canal treatment).

SOURCES

Electronic databases (PubMed, EMBASE, Cochrane Central) were screened, random-effects meta-analyses performed and trial-sequential analysis used to control for risk of random errors. Evidence was graded according to GRADE.

STUDY SELECTION

29 trials (4341 patients) were included, all but 6 showing high risk of bias. Based on 10 trials (1257 teeth), risk of complications was not significantly different in single-visit versus multiple-visit treatment (risk ratio (RR) 1.00 (95% CI 0.75 to 1.35); weak evidence). Based on 20 studies (3008 teeth), risk of pain did not significantly differ between treatments (RR 0.99 (95% CI 0.76 to 1.30); moderate evidence). Risk of flare-up was recorded by 8 studies (1110 teeth) and was significantly higher after single-visit versus multiple-visit treatment (RR 2.13 (95% CI 1.16 to 3.89); very weak evidence). Trial-sequential analysis revealed that firm evidence for benefit, harm or futility was not reached for any of the outcomes.

CONCLUSIONS

There is insufficient evidence to rule out whether important differences between both strategies exist.

CLINICAL SIGNIFICANCE

Dentists can provide root canal treatment in 1 or multiple visits. Given the possibly increased risk of flare-ups, multiple-visit treatment might be preferred for certain teeth (eg, those with periapical lesions).

Endodontic procedures for retreatment of periapical lesions

BACKGROUND

When primary root canal therapy fails, periapical lesions can be retreated with or without surgery. Root canal retreatment is a non-surgical procedure that involves removal of root canal filling materials from the tooth, followed by cleaning, shaping and obturating of the canals. Root-end resection is a surgical procedure that involves exposure of the periapical lesion through an osteotomy, surgical removal of the lesion, removal of part of the root-end tip, disinfection and, commonly, retrograde sealing or filling of the apical portion of the remaining root canal. This review updates one published in 2008.

OBJECTIVES

To assess effects of surgical and non-surgical therapy for retreatment of teeth with apical periodontitis.To assess effects of surgical root-end resection under various conditions, for example, when different materials, devices or techniques are used.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Trials Register (to 10 February 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1), MEDLINE Ovid (1946 to 10 February 2016) and Embase Ovid (1980 to 10 February 2016). We searched the US National Registry of Clinical Trials (ClinicalTrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials (to 10 February 2016). We placed no restrictions regarding language and publication date. We handsearched the reference lists of the studies retrieved and key journals in the field of endodontics.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) involving people with periapical pathosis. Studies could compare surgery versus non-surgical treatment or could compare different types of surgery. Outcome measures were healing of the periapical lesion assessed after one-year follow-up or longer; postoperative pain and discomfort; and adverse effects such as tooth loss, mobility, soft tissue recession, abscess, infection, neurological damage or loss of root sealing material evaluated through radiographs.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from included studies and assessed their risk of bias. We contacted study authors to obtain missing information. We combined results of trials assessing comparable outcomes using the fixed-effect model, with risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, and 95% confidence intervals (CIs). We used generic inverse variance for split-mouth studies.

MAIN RESULTS

We included 20 RCTs. Two trials at high risk of bias assessed surgery versus a non-surgical approach: root-end resection with root-end filling versus root canal retreatment. The other 18 trials evaluated different surgical protocols: cone beam computed tomography (CBCT) versus periapical radiography for preoperative assessment (one study at high risk of bias); antibiotic prophylaxis versus placebo (one study at unclear risk); different magnification devices (loupes, surgical microscope, endoscope) (two studies at high risk); types of incision (papilla base incision, sulcular incision) (one study at high risk and one at unclear risk); ultrasonic devices versus handpiece burs (one study at high risk); types of root-end filling material (glass ionomer cement, amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), gutta-percha (GP), super-ethoxy benzoic acid (EBA)) (five studies at high risk of bias, one at unclear risk and one at low risk); grafting versus no grafting (three studies at high risk and one at unclear risk); and low energy level laser therapy versus placebo (irradiation without laser activation) versus control (no use of the laser device) (one study at high risk).There was no clear evidence of superiority of the surgical or non-surgical approach for healing at one-year follow-up (RR 1.15, 95% CI 0.97 to 1.35; two RCTs, 126 participants) or at four- or 10-year follow-up (one RCT, 82 to 95 participants), although the evidence is very low quality. More participants in the surgically treated group reported pain in the first week after treatment (RR 3.34, 95% CI 2.05 to 5.43; one RCT, 87 participants; low quality evidence).In terms of surgical protocols, there was some inconclusive evidence that ultrasonic devices for root-end preparation may improve healing one year after retreatment, when compared with the traditional bur (RR 1.14, 95% CI 1.00 to 1.30; one RCT, 290 participants; low quality evidence).There was evidence of better healing when root-ends were filled with MTA than when they were treated by smoothing of orthograde GP root filling, after one-year follow-up (RR 1.60, 95% CI 1.14 to 2.24; one RCT, 46 participants; low quality evidence).There was no evidence that using CBCT rather than radiography for preoperative evaluation was advantageous for healing (RR 1.02, 95% CI 0.70 to 1.47; one RCT, 39 participants; very low quality evidence), nor that any magnification device affected healing more than any other (loupes versus endoscope at one year: RR 1.05, 95% CI 0.92 to 1.20; microscope versus endoscope at two years: RR 1.01, 95% CI 0.89 to 1.15; one RCT, 70 participants, low quality evidence).There was no evidence that antibiotic prophylaxis reduced incidence of postoperative infection (RR 0.49, 95% CI 0.09 to 2.64; one RCT, 250 participants; low quality evidence).There was some evidence that using a papilla base incision (PBI) may be beneficial for preservation of the interdental papilla compared with complete papilla mobilisation (one RCT (split-mouth), 12 participants/24 sites; very low quality evidence). There was no evidence of less pain in the PBI group at day 1 post surgery (one RCT, 38 participants; very low quality evidence).There was evidence that adjunctive use of a gel of plasma rich in growth factors reduced postoperative pain compared with no grafting (measured on visual analogue scale: one day postoperative MD -51.60 mm, 95% CI -63.43 to -39.77; one RCT, 36 participants; low quality evidence).There was no evidence that use of low energy level laser therapy (LLLT) prevented postoperative pain (very low quality evidence).

AUTHORS' CONCLUSIONS

Available evidence does not provide clinicians with reliable guidelines for treating periapical lesions. Further research is necessary to understand the effects of surgical versus non-surgical approaches, and to determine which surgical procedures provide the best results for periapical lesion healing and postoperative quality of life. Future studies should use standardised techniques and success criteria, precisely defined outcomes and the participant as the unit of analysis.

Magnification devices for endodontic therapy

BACKGROUND

After the introduction of microsurgical principles in endodontics involving new techniques for root canal treatment, there has been a drive to enhance the visualisation of the surgical field. It is important to know if the technical advantages for the operator brought in by magnification devices such as surgical microscopes, endoscopes and magnifying loupes, are also associated with advantages for the patient in terms of improvement of clinical and radiographic outcomes. This version updates the review published in 2009.

OBJECTIVES

To evaluate and compare the effects of endodontic treatment performed with the aid of magnification devices versus endodontic treatment without magnification devices. We also aimed to compare the different magnification devices used in endodontics with one another.

SEARCH METHODS

The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 13 October 2015), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2015, Issue 9), MEDLINE via OVID (1946 to 13 October 2015) and EMBASE via OVID (1980 to 13 October 2015). We searched the US National Institutes of Health Trials Register (http://clinicaltrials.gov) and the WHO Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We considered all randomised controlled trials (RCTs) and quasi-randomised controlled trials comparing endodontic therapy performed with versus without one or more magnification devices, as well as randomised and quasi-randomised trials comparing two or more magnification devices used as an adjunct to endodontic therapy.

DATA COLLECTION AND ANALYSIS

We conducted screening of search results independently and in duplicate. We obtained full papers for potentially relevant trials. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis.

MAIN RESULTS

No trials met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

No article was identified in the current literature that satisfied the criteria for inclusion. It is unknown if and how the type of magnification device affects the treatment outcome, considering the high number of factors that may have a significant impact on the success of endodontic surgical procedure. This should be investigated by further long-term, well-designed RCTs that conform to the CONSORT statement (www.consort-statement.org/).

Oral surgery: part 2. Endodontic surgery

In the past, the interaction between dentoalveolar surgery and restorative dentistry has been limited to the removal of teeth with pulp and/or periradicular disease or those that were unrestorable. However, with the increasing dental awareness of the population and the retention of teeth into later life, the interaction between dentoalveolar surgery and restorative dentistry is becoming a fundamental aspect of clinical practice. Indeed, endodontic and implant surgery are core activities that facilitate the retention of a functional dentition.

Pre- and postoperative management techniques. Part 3: before and after - endodontic surgery

In the last of this series of articles, the author will review some of the current interventions and advice that is most commonly used before and following endodontic surgical procedures. The aim of this article is to review the current evidence in the literature to support or refute current practices, management methods and protocols. The relative strength of the research discussed - including strengths and weaknesses - will be commented on. There are also some medicaments and instructions in dentistry that have no researched basis; some of these will also be identified and discussed.

Monitoring Nonsurgical and Surgical Root Canal Treatment of Teeth with Primary and Secondary Infections

The aim of this study was to monitor nonsurgical and surgical root canal treatment (RCT) of teeth with primary and secondary infections and apical periodontitis (AP). This prospective clinical study comprised the treatment of 80 patients with primary and persistent secondary infections and AP. Of this initial sample, forty patients did not return. Periapical index using cone beam computed tomography scans (CBCTPAI) was used to aid diagnosis, planning and to determine the better therapeutic strategy. Twenty patients (26 teeth) diagnosed with primary infection and AP received conventional RCT and were followed up for 10 to 36 months. Twenty patients (31 teeth) diagnosed with persistent secondary infection were submitted to periapical surgical and followed up for 6 to 30 months. The results showed RCT successful in 19/26 cases with complete AP healing (5/26 with partial repair) in 10-36 months of follow up. For the surgically managed cases, effectiveness of surgical therapy was detected in 10/31 cases with complete healing (10/31 cases with partial repair) within 6-30 months follow up. The return of patients for clinical and radiographic follow-up, and obedience to the proposed time period was very short from ideal. The levels of success in both therapeutic protocols were high. RCT failures were detected even with rigorous standard clinical protocols.

Postextraction implant in sites with endodontic infection as an alternative to endodontic retreatment: a review of literature

The aim of this literature review is to evaluate the outcomes of implants placed after extraction of teeth with infections of endodontic origin. An electronic search was performed through electronic databases (Medline and Embase) using the terms "immediate implant," "post-extractive implants," "endodontic infection," "infected site," and "extraction socket" combined with the use of Boolean operators ("AND" and "OR"). Only articles on human subjects were considered. At least 12 month of mean follow-up was required for inclusion. No restriction was placed regarding study design. Ten studies were included in this review. Survival rates ranged from 92% to 100%. A total of 497 implants were placed in sites with endodontic infection. In nine studies the use of bone substitutes was associated with immediate implant placement. Because of the low number of included studies and the heterogeneity of study design, more well-designed studies are required to assess the relevance of this treatment alternative.

Non-surgical endodontics in retreatment of periapical lesions - two representative case reports

This article reports non-surgical endodontic retreatment of two patients with persistent or recurrent periapical lesions, who had previously undergone surgical and non-surgical endodontic therapy respectively. It further discusses and reviews the relevance of classification of periapical lesions, the explanation behind healing of periapical lesions by endodontic therapy alone, causes of persistence of periapical lesions, choice of treatment modalities (whether surgical or non - surgical) and materials such as intracanal medicaments and irrigants for optimal healing. Key words:Non-surgical, retreatment, periapical, calcium hydroxide, chlorhexidine irrigation.

Magnification devices for endodontic therapy

BACKGROUND

After the introduction of microsurgical principles in endodontics, involving new techniques for root canal treatment, there has been a continuous search for enhancing the visualisation of the surgical field. It would be interesting to know if the technical advantages for the operator brought in by magnification devices like surgical microscope, endoscope and magnifying loupes, are also associated with advantages for the patient, in terms of improvement of clinical and radiographic outcomes.

OBJECTIVES

The purpose of this systematic review was to evaluate and compare the effects of endodontic treatment performed with the aid of magnification devices versus endodontic treatment without magnification devices. We also aimed at comparing among them the different magnification devices used in endodontics (microscope, endoscope, magnifying loupes).

SEARCH STRATEGY

The Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE and EMBASE were searched with appropriate search strategies. Handsearching included nine dental journals. The bibliographies of relevant clinical trials and relevant articles were checked for identifying studies outside the handsearched journals. Seven manufacturers of instruments in the field of endodontics and/or endodontic surgery, as well as the authors of the identified randomised controlled trials (RCTs) were contacted in order to identify unpublished or ongoing RCTs. There were no language restrictions. The last electronic search was conducted on 2nd April 2009, and the last handsearching was undertaken on 31st January 2009.

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing endodontic therapy performed with or without using one or more types of magnification device, as well as randomised and quasi-randomised trials comparing two or more magnification devices used as an adjunct to endodontic therapy were considered.

DATA COLLECTION AND ANALYSIS

Screening of studies and data extraction were conducted independently and in duplicate. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis.

MAIN RESULTS

No trial could be included in the present review. All of the prospective trials that were identified, all dealing with endodontic surgery, had to be excluded for various reasons. Only one RCT was identified comparing three magnificators (magnifying loupes, surgical microscope, endoscope) in endodontic surgery. No RCT was found that compared the outcome of endodontic therapy using or without using a given magnification device.

AUTHORS' CONCLUSIONS

No objective conclusion can be drawn from the results of this review as no article was identified in the current literature that satisfied the criteria for inclusion. It is unknown if and how the type of magnification device affects the treatment outcome, considering the high number of factors that may have a significant impact on the success of endodontic surgical procedure. This should be investigated by further long-term RCTs with large sample size. Technical advantages of magnificators have been widely reported in low evidence level studies, but they should be systematically addressed to know if there can be the clinical indication for using a given magnification device for specific clinical situations, such as for molar teeth, or if they can all be used interchangeably. Well-designed RCTs should also be performed to determine the true difference in terms of treatment success rates between using or not using a magnification device in both conventional and surgical endodontic treatment, if any exist.

Periodontal and endodontic regeneration

Guided tissue regeneration (GTR) is effective in halting tissue and bone destruction and promoting new tissue and bone formation. Although the goal of complete and predictable regeneration still remains elusive, many techniques and materials have been developed that show good clinical and histologic outcomes. The most commonly used materials in GTR include bone replacement grafts from numerous sources, nonresorbable and bioabsorbable membranes, and recently growth hormones/cytokines and other host modulating factors. This article reviews the biologic rationale behind current techniques used for tissue/bone regeneration, reviews the most common materials and techniques, and attempts to explain the factors that influence the outcomes of these therapies.