Given the task definition and input, reply with output. Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: The Cochrane Central Register of Controlled Trials, PubMed Medline and Latin American and Caribbean Health Science literature databases were searched, and searches made by hand of identified papers, to source relevant data. (BIOSIS Previews) were searched. There were no language restrictions.', 'Studies were evaluated by two reviewers independently. Only clinical trials were included that were published in the English, Spanish and Portuguese languages and were performed on humans. Articles were excluded when the examiners were not calibrated; when they did not compare manual and electronic probing techniques; when they did not measure the clinical attachment level (CAL); and when the subjects did not present destructive periodontal disease or had already received periodontal treatment.', 'The quality of the identified studies was assessed and standardised data extracted. Only two studies met all the selection criteria so no meta-analysis was performed.', 'Only two of the 37 identified articles were included in the review. The results of these two studies showed that the mean variance and the absolute mean difference between CAL measurements for the two types of probes were not statistically different.
Answer: Manual and electronic probes were of similar reliability when used to measure CAL in individuals who had untreated periodontitis and when used by a calibrated examiner, but this finding is not supported by strong evidence.
Do manual and electronic probes have similar reliability in the measurement of untreated periodontitis?