QUINTESSENCE INTERNATIONAL

Clemens Walter Cone beam computed tomography (CBCT) for diagnosis and treatment planning in periodontology: A systematic review

Clemens Walter, PD Dr Med Dent1/Julia C. Schmidt, Dr Med Dent2/Karl Dula, Prof Dr Med Dent3/ Anton Sculean, Prof Dr Med Dent, MS, Dr hc4

Objective: The improvement in diagnostic accuracy and opti- aspects related to vertical bony defects. Two studies show a mization of treatment planning in periodontology through the high accuracy of CBCT in detecting intrabony defect morphol- use of three-dimensional imaging with cone beam computed ogy when compared to periapical radiographs. Particularly, in tomography (CBCT) is discussed controversially in the litera- maxillary molars, CBCT provides high accuracy for detecting ture. The objective was to identify the best available external furcation involvement and morphology of surrounding peri- evidence for the indications of CBCT for periodontal diagnosis odontal tissues. CBCT has demonstrated advantages, when and treatment planning in specific clinical situations. Data more invasive treatment approaches were considered in terms Sources: A systematic literature search was performed for of decision making and cost benefit. Within their limits, the articles published by 2 March 2015 using electronic databases available data suggest that CBCT may improve diagnostic and hand search. Two reviewers performed the study selec- accuracy and optimize treatment planning in periodontal tion, data collection, and validity assessment. PICO and PRISMA defects, particularly in maxillary molars with furcation involve- criteria were applied. From the combined search, seven studies ment, and that the higher irradiation doses and cost-benefit were finally included. Conclusion: The case series were pub- ratio should be carefully analyzed before using CBCT for peri- lished from the years 2009 to 2014. Five of the included publi- odontal diagnosis and treatment planning. (Quintessence Int cations refer to maxillary and/or mandibular molars and two to 2016;47:25–37; doi: 10.3290/j.qi.a34724)

Key words: cone beam computed tomography, decision making, diagnosis, furcation involvement, furcation surgery, regenerative , three-dimensional imaging

Dental cone beam computed tomography (CBCT) pro- 1 Director of Postgraduate Program in Periodontology, Department of Periodon- tology, Endodontology and Cariology, University of Basel, Basel, Switzerland. vides good image quality with less radiation exposure 2 Postgraduate Student, Department of Periodontology, Endodontology and than conventional CT devices.1,2 Recently, several appli- Cariology, University of Basel, Basel, Switzerland. cations have been discussed in and guide- 3 Associate Professor, Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland. lines for indications and use were published.1-3 How- 4 Professor and Chairman, Department of Periodontology, School of Dental Med- ever, CBCT diagnostic accuracy has mostly been veri- icine, University of Bern, Bern, Switzerland. fied in detection and quantification of periodontal Correspondence: Professor Anton Sculean, Department of Periodon- defects in in-vitro settings, particularly on human tology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, 3010 Bern, Switzerland. Email: [email protected] skulls.4-7

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Increased pocket probing depths (PPD) are fre- Severely compromised molars with FI have an quently related to the presence of intrabony (angular) increased risk of additional vertical and horizontal periodontal defects which, when left untreated, have attachment loss, probably leading to an impaired long- been shown to worsen long-term tooth prognosis.8 term prognosis and tooth loss.15 It is well known that Findings from clinical studies have shown that peri- maxillary molars respond less favorably (in terms of odontal surgery involving various types of access flaps remaining increased periodontal pockets) to nonsurgi- and use of different biomaterials may result in PPD cal periodontal treatment.17,18 In addition, it has been reduction, hard tissue fill or even complete elimination demonstrated that PPD of ≥ 6 mm require further ther- of the intrabony component.9 It has been demon- apy in order to reduce or eliminate ongoing loss of strated that the healing of intrabony defects is strongly periodontal attachment.19 Therefore, particularly in dependent upon defect anatomy (ie, contained type molars there is a need for further treatment (Fig 1). In defects reveal a higher healing potential compared to order to select the appropriate surgical treatment defects with a more complicated non-contained anat- option, a thorough diagnosis is required, which com- omy). Thus, in order to improve the clinical outcomes, prises the estimation of the bony component, the it is recommended that the used surgical technique degree of horizontal and vertical FI, the assessment of and the choice of regenerative materials or combina- the residual inter- and periradicular bone, and the tion thereof should be based on the accurate analysis evaluation of the root morphology. Clinical diagnosis is of defect anatomy.10 When considering regenerative generally based on PPD, probing attachment level periodontal surgery, the preoperative diagnosis and (PAL), probing of the furcation entrance, and periapical evaluation of the outcomes are made by means of peri- radiographs.20 Accurate analysis of the defect morphol- odontal probing, periapical radiographs, and bone ogy, however, is not feasible in many instances due to sounding. Since periodontal probing is strongly depen- limited access, morphologic variations, and measure- dent on factors such as tissue inflammation, probe type ment errors.15 Since conventional 2D radiographic and diameter, probing force, and angulation of the imaging may have some relevant drawbacks, it might probe, the measured values may under- or overesti- be useful to analyze distinct clinical situations, particu- mate the real defect depth.11 Periapical radiographs larly vertical bony defects and maxillary molar teeth, provide only a two-dimensional (2D) image, are difficult with a three-dimensional (3D) diagnostic approach. to standardize, and may underestimate the depth and The purpose of the present systematic review was the configuration of the intrabony defect.12 Thus, there to identify the best available evidence for the indica- is a need for more accurate methods to adequately tions of CBCT for periodontal diagnosis and treatment diagnose the anatomy of intrabony defects in order to of specific clinical situations, with respect to accuracy optimize treatment planning and to enable a more and a potential benefit of dental CBCT. objective evaluation of the outcomes following regen- The specific questions in this systematic review erative surgery. were addressed according to the PICO (Patient, Inter- Multiple factors influence the prognosis of furca- vention, Comparison, Outcomes) criteria:21 tion-involved teeth, including:13-16 1. In patients suffering from periodontitis (P), which • tooth-related factors such as furcation involvement accuracy (O) of dental CBCT can be expected in (FI) degree III, and bone loss at the initiation of peri- assessing (maxillary) molars with FI when compared odontal therapy to findings obtained from clinical measurements (C)? • factors related to the dentition such as the number 2. In patients suffering from periodontitis (P), which of molars remaining accuracy of dental CBCT (O) can be expected in • patient-related factors such as smoking habits, and assessing vertical bony defects when compared to the applied treatment modality. findings obtained from clinical measurements (C)?

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Figs 1a to 1d A 51-year-old woman with generalized advanced .

Fig 1a Periodon- tal status of maxil- lary left teeth in advance of retreat- Fig 1b Periapical radiograph of the maxillary left first and sec- ment after system- ond molars. Interradicular bone loss and the amount of residual atic nonsurgical periodontal attachment of each maxillary molar root is not clear- periodontal thera- ly discernible. 3D imaging was performed in order to gather py 14 years previ- additional necessary information on the anatomy and to define ously.40 further periodontal treatment.15

c d Figs 1c and 1d CBCT images with horizontal, sagittal, and transversal sections (3D Accuitomo 60, XYZ Slice View Tomograph; J Morita). The maxillary left first molar (c) exhibited FI degree III in all furcations and significant loss of the interradicular bone and the proximal bone shared with the maxillary left second molar. It was decided to extract the maxillary left first molar (GoI degree 5) due to the extensive periodontal breakdown and the limited prognosis of this tooth.15 In contrast, the maxillary left second molar showed a single root with sufficient bone support with the opportunity for tooth retention in the long term. An open flap with distal wedge excision (GoI degree 1) was planned for the maxillary left second molar.41

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Figs 1e to 1j A 51-year-old woman with generalized advanced chronic periodontitis.

Fig 1e Presurgical view of the maxillary left first and second molars.

Fig 1f Incisions on the buccal and the palatal site prior to reflection of mucoperi- osteal flaps.

Fig 1g Intrasurgical view after extraction of the maxillary left first molar.

efg

Fig 1h The flaps were repositioned and the wound was sutured with monofil syn- thetic material (5 × 0).

Fig 1i The extracted maxillary left first molar.

Fig 1j Five months postoperatively, the hi j wound healing was uneventful.

3. In patients suffering from periodontitis (P), which DATA SOURCES benefit (O) of dental CBCT use compared to conven- tional clinical and radiographic diagnostics (C) can Study selection be expected, when vertical bony defects or (maxil- Publications were considered eligible for inclusion in lary) molars with FI were analyzed? this systematic review if they presented the following parameters: The present systematic review considers the PRISMA • clinical or comparative radiographic study per- (Preferred Reporting Items for Systematic Review and formed in humans Meta-Analyses) criteria.22,23 • use of dental CBCT • data on periodontal defects (ie, furcation defects or vertical bony defects).

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A publication considered ineligible for inclusion was The studies reported on the distribution of FI with differ- hierarchically categorized according to one of the fol- ent degrees in molars, and the distance between the lowing main reasons for exclusion: cementoenamel junction (CEJ) and the alveolar bone • N1 – in vitro study, animal study, case report or crest (AC) or the bottom of the bony defect (BD). The review article potential benefit of CBCT in terms of decision making or • N2 – no use of digital volume tomography a reduction of treatment time and/or costs was assessed. • N3 – no analysis of periodontal defects Owing to the limited number of clinical studies, a • N4 – not in the English language. pooling of data or statistical meta-analyses was not appropriate and therefore not performed. Outcome measures The primary outcome measure was accuracy of dental REVIEW CBCT compared to clinical measures or conventional radio- graphic images. Any potential benefit of a dental CBCT use Study selection (eg, cost benefit or in terms of favorable decision making) A total of 147 titles from the electronic databases were was considered as secondary outcome parameter. identified (Fig 2). The abstracts of selected titles were screened by two reviewers (observed agree- Information sources and literature search ment = 95.00%, kappa = 0.886, intraclass correlation A MEDLINE search (PubMed) until 2 March 2015 was coefficient = 0.891). The full texts of seven publications conducted using the keywords “” (selected by at least one reviewer) were further ana- AND “computed tomography” AND “imaging” AND lyzed. Full text analysis led to exclusion of further two (“furcation defect” OR “alveolar bone loss”). This search studies (Table 1). Finally, seven publications from the was supplemented with hand searching of pertinent combined search satisfied the inclusion criteria. The journals and bibliographies of reports examined for included publications comprised seven case series pub- inclusion eligibility. Any relevant work published in the lished in the period from 2009 to 2014. English language and presenting relevant information about the described issue was considered for inclusion Description of characteristics, results, and in the review. In addition to this structured review pro- quality assessment cess, a narrative approach was conducted on the aspects The characteristics and results related to outcome par- related to regenerative periodontal surgery, diagnosis of ameters of included studies are summarized in Tables 2 FI, and treatment planning. The literature implemented and 3. in this part of the review was thoroughly discussed among the authors until a consensus was achieved. Population: number and characteristics of patients and tooth sites According to the three specific questions the data were RESOURCES SELECTION presented separately for either topic. The following data of included publications were col- 1. Three of the included publications referred to the lected in data extraction files: same study group.24-26 The mean age of patients in • study design the included publications was 57.0 years, 57.5 years, • characteristics of probands or 43.5 years, or the patients aged between 18 and • radiographic method/device 85 years.24-28 The proportion of men and women • radiographic assessment was stated as nine men and three or five women, • mode of periodontal assessment and six men and nine women.24-27 One of the • comparison. included studies described exclusion criteria in

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Records identifi ed through electronic database searching (n = 147) cation

Records after duplicates removed Identifi (n = 147)

Titles screened Records excluded based on title (n = 147) screening (n = 127)

Abstracts screened Records excluded based on abstract (n = 20) screening (n = 13) Screening Main reasons for exclusions: (N1) in vitro, animal study, case report, or review article (7) (N2) no digital volume tomography (3) (N3) no periodontal defects (2) (N4) not in English language (1)

Full-text articles assessed Full-text articles excluded (n = 2) for eligibility Main reasons for exclusions: (n = 7) (N1) in vitro, animal study, case report, or Eligibility review article (1) (N2) no digital volume tomography (1)

Publications included based on hand search and screening of the references of included studies (n = 2)

Included Publications included in qualitative synthesis (n = 7)

Fig 2 Selection process of the studies included.22

terms of the presence of furcation caries, metal all, the accuracy of CBCT was analyzed in 130 teeth crowns in the CBCT irradiation area, silver amalgam with a total of 280 furcation entrances.24-28 All fi llings near the alveolar crest, and pregnant or lac- patients had a diagnosis of generalized chronic tating women.27 In one study, smoking habits of the periodontitis.24-28 Patients with at least one maxil- patients were described as including six never lary molar with persisting increased PPD ≥ 6 mm smokers, two former heavy smokers (> 20 ciga- and/or FI degree II or III were considered for inclu- rettes per day), one light smoker (fi ve cigarettes per sion.24-27,29 In one study, patients were included if day), and three currently heavy smokers.24 The pub- they had both clinically diagnosed FI degree I, II, or lications investigated each between 20 and 85 III and CBCT scans.28,29 Initial periodontal treatment teeth with 51 to 154 furcation entrances.27,28 Over- in terms of was performed

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6 months or at least 3 to 6 months before inclusion in the study.24-27 Table 1 Excluded publications and reason for exclusion 2. Patients were between the ages of 35 and 65 years, and 39 and 66 years.30,31 The proportion of females Reason for exclusion based on Study full text or abstract screening and males was provided in one of the two publica- Acar and Kamburoğlu42 N1 tions as including 17 males and 12 females.31 The Laky et al43 N2 two studies investigated 35 vertical bone defects, Coelho et al44 N1 39 teeth with a total of 15 vertical bone defects, and Zhang et al44 N3 30,31 36 sites with horizontal bone loss, respectively. A Torres et al45 N1 moderate to severe chronic periodontitis was diag- Ising et al46 N1 nosed in all probands in one of the included stud- Yagci et al47 N3 ies.31 Patients with at least one interproximal site Kumar et al48 N2 with PPD ≥ 5 mm and a vertical bone defect ≥ 3 mm Sun et al49 N1 on a periapical radiograph, and the ability to sit for Leung et al50 N1 all required radiographic exams were considered for Teslaru et al51 N4 inclusion.31 After initial periodontal treatment con- Naitoh et al52 N1 sisting of scaling and root planing, a surgical treat- Misch et al4 N1 53 ment was initiated involving proced- Pistorius et al N2 Naito et al54 N2 ures, followed by reentry surgery ≥ 6 months later.31 N1, in vitro study, human skulls, animal study, case report or review article; N2, no CBCT; Inclusion criteria for radiographs were adequate N3, no periodontal defects; N4, not in English language. density and contrast, centralization of the region assessed, and visualization of the CEJ.30 Reasons for ameters evaluated for comparison in the second study exclusion were interproximal overlap in periapical were the identification of the pattern of bone loss, the radiographs, metallic restorations with scatter height of the alveolar crest (CEJ to AC), as well as the effects, metal restorations in CBCT images, and a defect depth (CEJ to BD) and the defect width (AC to compromised CEJ, or an undetectable reference dental root adjacent to the defect) in CBCT and periapi- point for radiographic measurements.30,31 cal radiographs.30 3. Two publications of the five articles, as described in Treatment recommendations based on clinical the first point above, provided data for the ques- evaluation and periapical radiographs alone were com- tion.24,26 pared to decision making following supplemental CBCT imaging.24 A cost benefit analysis was performed for Intervention/comparison CBCT imaging in maxillary molars.26 The degree of furcation involvement obtained by peri- odontal probing or intrasurgical assessments was com- Outcome pared to the degree estimated from CBCT imag- Using presurgical measurements, 22% or 27% of the ing.24,25,27,28 clinical findings were confirmed in the CBCT, while 29% Measurements from periapical radiographs and or 58% were overestimated (CBCT < clinical value) and from CBCT images were compared to direct surgical 20% or 44% revealed an underestimation.24,28 CBCT measurements taken at initial surgery and at reentry assessments of furcation involvement were confirmed surgery ≥ 6 months later.31 The radiographic and clin- by intrasurgical findings in 82.4% or 84%, respect- ical assessments included the height of the alveolar ively.25,27 crest (CEJ to AC) and the defect depth (CEJ to BD), and There were significant differences between the the defect fill and resolution were calculated.31 The par- measurements performed on CBCT and periapical

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Table 2 Characteristics and outcome parameters of included studies on accuracy of CBCT in maxillary molars

Study Study design Proband characteristics Radiographic method/device Radiographic assessment FI (classification of Hamp et al29), supported-un- 12 patients (3 F, 9 M; mean CBCT (3D Accuitomo 60, XYZ Walter et al24 Case series supported tooth length ratio, anatomical fea- age 57.5 y, range 41–80 y) Slice View Tomograph [J. Morita]) tures (eg, root fusions, root proximity) 14 patients (5 F, 9 M; mean CBCT (3D Accuitomo 60, XYZ Walter et al25 Case series FI (classification of Hamp et al29) age 57.0 y, range 42–81 y) Slice View Tomograph [J. Morita])

FI (classification of Hamp et al29), supported-un- 12 patients (3 F, 9 M; mean CBCT (3D Accuitomo 60, XYZ Walter et al26 Case series supported tooth length ratio, anatomical fea- age 57.5 y, range 41–80 y) Slice View Tomograph [J. Morita]) tures (eg, root fusions, root proximity)

15 patients (9 F, 6 M; mean CBCT (3D Accuitomo 60, XYZ Qiao et al27 Case series FI (classification of Hamp et al29), BL-V, RT, FW age 43.5 y) Slice View Tomograph [J. Morita]) FI (maxillary furcations: graduation by radiolu- 27 patients (age range CBCT (Platinum i-CAT, Imaging Darby et al28 Case series cencies on sagittal slices; mandibular furcations 18–85 y) Sciences International) by classification of Hamp et al29), root fusions

BL-V, vertical bone loss; CBCT, cone beam computed tomography; F, female; FI, furcation involvement; FW, width of furcation entrance; M, male; NR, not reported; RT, length of the root trunk.

Table 3 Characteristics and outcome parameters of included studies on accuracy of CBCT in detecting vertical bony defects

Proband Radiographic Study Study design characteristics method/device Radiographic assessment Initial CEJ to AC

Measure- Reentry CEJ to AC ments Initial CEJ to BD Reentry CEJ to BD Initial defect depth (CEJ to BD − CEJ to AC) 29 patients CBCT (3DX Accuitomo Grimard et Reentry defect depth (CEJ to BD − CEJ to AC) Case series (12 F, 17 M; age [J. Morita]); periapical radio- al31 range 35–65 y) graphs Defect fill (initial CEJ to BD − reentry CEJ to BD); Calculated values Defect resolution (initial defect depth − reentry defect depth)

CBCT (i-CAT CBCT scanner, Imag- De Faria 11 patients ing Sciences International), Pattern of bone loss (horizontal or vertical); CEJ to AC; CEJ to Vasconcelos Case series (M & F; age Periapical radiographs (Spectro BD; AC to adjacent dental root; combination of bone defects et al30 range 39–66 y) 70X Seletronic Dental X-ray (classification of Goldman and Cohen55) machine, Dabi Atlante)

AC, alveolar crest; BD, bottom of the defect; CBCT, cone beam computed tomography; CEJ, cementoenamel junction; F, female; M, male; NR, not reported.

images, with respect to the distance CEJ to AC.30 CBCT fill, 82% of the CBCT measurements were assessments of the height of the alveolar crest (CEJ to within ≤ 2 mm of the surgical measurements.31 CBCT AC) and the defect depth (CEJ to BD) were findings of defect resolution were within ≤ 2 mm of the within ≤ 2 mm of the surgical findings in 94% to 100% surgical findings in 73%, respectively.31 and in 91% to 94%, respectively.31 With regard to defect

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Periodontal assessment Accuracy Potential benefit of CBCT

Comparison – degree of FI; CBCT = clinical, 27%; CBCT < Discrepancies between the CBCT-based and the clinical Nonsurgical clinical, 29%; CBCT > clinical, 44% therapeutic approaches between 59% and 82%

Comparison – degree of FI; CBCT = intrasurgical, 84%; Intrasurgical NR CBCT < intrasurgical, 14.7%; CBCT > intrasurgical, 1.3% Average cost reduction from CBCT, CHF 915 ± 1,470 Average time reduction from CBCT, 136 ± 217 min Nonsurgical NR Greatest cost reductions with maximal invasive clinically based treatment decisions (CHF 1,566 ± 1,840) Comparison – degree of FI; CBCT = intrasurgical, 82.4%; Intrasurgical NR CBCT < intrasurgical, 11.7%; CBCT > intrasurgical, 5.9%

Comparison – degree of FI; CBCT = clinical, 22%; CBCT < Nonsurgical NR clinical, 58%; CBCT > clinical, 20%

Periodontal assessment Accuracy Potential benefit of CBCT Initial CEJ to AC, 73%, 94% Reentry CEJ to AC, 88%, 100% Frequency of CBCT mea- surements within ≤ 1 mm Initial CEJ to BD, 61%, 91% and ≤ 2 mm compared to Intrasurgical at baseline Reentry CEJ to BD, 58%, 94% surgical measurements (initial); intrasurgical at Defect fill, 55%, 82% No significant differences with respect to defect fill, reentry; periodontal resolution and extent of vertical defect (CEJ to AC) probe (UNC- 15, Defect resolution, 58%, 73% between surgical and CBCT. Substitution for surgical Hu-Friedy) Initial CEJ to AC, 55%, 77% measurements of defect fill and defect resolution after bone-replacement graft procedures. Frequency of periapical Reentry CEJ to AC, 48%, 84% radiographs measurements Initial CEJ to BD, 23%, 52% within ≤ 1 mm and ≤ 2 mm compared to surgical mea- Reentry CEJ to BD, 35%, 68% surements Defect fill, 41%, 62% Defect resolution, 31%, 59%

No significant differences in identification of pattern of bone loss; CEJ to AC, significant differences between periapical radio- Identification of defect morphology; analysis of buc- NR graphs (mean 3.8 mm) and CBCT (mean 4.1 mm); CEJ to BD, no cal and lingual/palatal surfaces significant differences; AC to adjacent dental root, no significant differences

The analysis of clinical data and periapical radio- potential benefit of dental CBCT use the Graduation of graphs indicated more than one treatment option in Invasiveness (GoI) was applied.15,24 In the GoI the treat- most maxillary molars, and the additional CBCT analysis ment options for maxillary molars were graduated from facilitated a clear decision for further periodontal treat- a less invasive approach (ie, keeping as much periodon- ment in all teeth investigated.24 For the analysis of any tal attachment as possible) to a more invasive approach:

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• open flap debridement with/without AC on CBCT images differed significantly compared to or apically repositioned flap and/or tunneling measurements on periapical radiographs.30 • root separation Several authors have reported difficulties in cor- • amputation/trisection of a root (with/without root rectly estimating the furcation involvement of maxillary separation or tunnel preparation) molar teeth from clinical measurements and periapical • amputation/trisection of two roots radiographs.32,33 Due to the limited options to properly • extraction of the entire tooth. estimate the horizontal attachment loss of maxillary molars, intraoperative alteration of a treatment plan is Discrepancies between the CBCT-based and the clinical frequently required. It is obvious that the accurate therapeutic approaches amounted to 59% with the less detection of the furcation involvement and the assess- invasive treatment (P = .084), rising to as much as 82% ment of the root morphology affects the diagnosis and when the most invasive treatment recommendation is consequently essential for the choice of treatment, was selected (P = .004). Average cost reduction from the tooth prognosis, and the maintenance procedures CBCT of maxillary molars amounted to CHF 915 ± 1,470 (Fig 1). The CBCT facilitates more detailed surgical treat- and saved 136 ± 217 minutes.26 The greatest reductions ment planning with a clear decision about resective were found with maximally invasive clinically based interventions, with a specification of the roots that are treatment decisions (CHF 1,566 ± 1,840), particularly for planned to be kept.24 In addition, the CBCT enables the second molars (CHF 2,485 ± 2,226). To compensate estimation of periapical lesions, or combined periodon- CBCT costs, 1.7 subjects were needed to treat to at least tal-endodontic lesions, the assessment of the existing break even. With regard to the treatment of vertical root canal treatment, and the appraisal of the second bony defect, there are no data from a cost benefit mesiobuccal root canal.15 analys is available. However, the findings from a preliminary cost bene- fit analysis using the GoI approach indicated the need for a critical appraisal of CBCT applications in maxillary DISCUSSION molars.15,26 In most cases with clinically based GoI ≤ 1 (0: The present systematic review aimed to identify the supportive periodontal treatment, 1a/b: open flap best available external evidence for the application of debridement), CBCT imaging seems to have no or only CBCT in periodontology. Sufficient evidence from three minor impact in terms of an economic benefit or reduc- different populations indicates a high accuracy of CBCT tion in treatment time. With more invasive clinically imaging for the analysis of furcation involvement of based treatment decisions (> degree 1 in the GoI), how- maxillary molars in particular.24,25,27,28 In addition, data ever, the benefits of using CBCT were greater, probably from one case series indicate a discrepancy in treat- because the indication for tooth extraction is clarified ment recommendations for the majority of molars with (Fig 1). On the one hand, a straightforward tooth the treatment decisions based on clinical data and extraction followed by implant placement and restor- periapical radiographs compared to those obtained by ations is feasible, thereby avoiding explorative peri- additional CBCT. A possible reduction in treatment odontal surgeries when the tooth is not maintainable. costs and time for periodontally involved maxillary Also, unnecessary tooth extractions and implant place- molars in Switzerland was demonstrated by one pre- ment in sites where teeth would be maintainable may liminary analysis.26 High agreements between CBCT be avoided. Moreover, root canal treatments in sites and clinical findings were further demonstrated with planned for GoI degrees 2, 3, or 4 (separation, amputa- respect to the measurements of the height of the alve- tion, or trisection) may be prevented, when CBCT olar crest (CEJ to AC), the defect fill, and the resolu- revealed morphologic variations such as root proximi- tion.30,31 In contrast, assessments of the distance CEJ to ties or root fusions, which precluded the clinically based

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resective treatment planning. The financial benefits of Although limited available evidence appears also to using CBCT and/or the savings in in-office time were indicate that, at present, CBCT is the most accurate more pronounced in maxillary second molars than in method to determine the morphology of the intrabony first molars. These differences were most likely related defects, it may thus be used for a more accurate diagno- to the different morphologies of these teeth, ie, the sis and treatment planning in demanding cases. Fur- reduced degree of root separation in maxillary second thermore, CBCT may also represent a realistic alternative molars. This is potentially associated with errors in furca- to reentry surgery and periapical radiographs for assess- tion diagnoses and inappropriate treatment decisions. ing the outcomes of periodontal therapy. On the other As a consequence, indications for resective treatment of hand, further studies are needed to determine the ben- furcation-involved maxillary second molars seem to be efit of using this technique in the diagnosis and treat- restricted.26 Further limitations in this situation arise ment of intrabony defects by taking into consideration from the difficulty of gaining adequate access and of the higher irradiation doses and cost-benefit ratio. performing procedures in the distal maxil- lary area even after periodontal furcation surgery.34 CONCLUSION Extracting periodontally compromised maxillary second molars is a treatment option provided that the first This (updated) systematic review was conducted as a molar is intact. Comprehensive treatment with CBCT part of the consensus meeting 2014 for the develop- imaging may also be indicated for restorative reasons, ment of the SADMFR Guidelines for the Use of Cone- particularly when deciding whether to maintain an Beam Computed Tomography in Switzerland.39 Accord- important abutment tooth.15 Obviously, there is often a ing to the literature analyzed, the following conclusions need to augment the maxillary sinus when a maxillary can be drawn: molar with furcation involvement is extracted.35 To • CBCT provides high accuracy in detecting the mor- avoid augmenting the maxillary sinus to facilitate phology of vertical bony defects. However, for the implant placement is a reliable treatment goal for many reasons outlined above, its routine use for assessing clinicians (and their patients).36,37 However, in certain intrabony defects is not recommended. cases, there is no indication to replace a furcation • Particularly, in maxillary molars, CBCT provides high involved second molar with a , and the accuracy for detecting furcation involvement and shortened dental arch (SDA) concept is applied with no morphology of surrounding periodontal tissues. replacement of the functional unit. Interestingly, with CBCT has demonstrated advantages, when more respect to periodontal parameters some benefits of the invasive treatment approaches were considered, SDA concept compared to a removable partial denture and can thus aid complex treatment planning. were documented in a randomized controlled trial.38 • Radiographic imaging using CBCT still enables a The application of dental CBCT enables a distinct higher radiation dose compared to conventional 2D and more detailed assessment of furcation involvement images, including periapical radiographs and pan- in maxillary molars than with the conventional ap- oramic images.39 Therefore, the use of CBCT and its proach using clinical measurements and periapical potential risks and benefits needs to be carefully radiographs. The additional CBCT analysis revealed considered according to the ALARA (As Low as Rea- discrepancies in treatment recommendations and a sonably Achievable) principle in each individual reduction of treatment time and costs for some maxil- case. lary molars. Employing this radiographic tool for treat- ment planning in selected furcation-involved maxillary molars may help to verify the clinical diagnosis and avoid redundant surgical or endodontic interventions.

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